You are an expert at summarizing long articles. Proceed to summarize the following text: 
during recent years there has been increasing evidence for a connection between active galactic nuclei ( agn ) and star formation in the vicinity of the central black holes . this subject forms the central topic of this paper , and is discussed in sections  [ sec : prop ] and  [ sec : staragn ] . a large number of studies have addressed the issue of star formation around agn . those which have probed closest to the nucleus , typically on scales of a few hundred parsecs , have tended to focus on seyferts  notably seyfert2 galaxies  since these are the closest examples @xcite . the overall conclusion of these studies is that in 3050% cases the agn is associated with young ( i.e. age less than a few 100myr ) star formation . while this certainly implies a link , it does not necessarily imply any _ causal _ link between the two phenomena . instead , it could more simply be a natural consequence of the fact that both agn and starburst require gas to fuel them . and that in some galaxies this gas has fallen towards the nucleus , either due to an interaction or secular evolution such as bar driven inflow . one aspect which must be borne in mind when interpreting such results , and which has been pointed out by @xcite , is the discrepancy in the scales involved . agn and starburst phemonena occur on different temporal and spatial scales ; and observations are sensitive to scales that are different again . for example , star formation has typically been studied on scales of several kiloparsecs down to a few hundred parsecs . in contrast , accretion of gas onto an agn will occur on scales much less than 1pc . similarly , the shortest star formation timescales that most observations are sensitive to are of order 100myr to 1gyr . on the other hand , in this paper we show that the active phase of star formation close around a black hole is typically rather less than 100myr . correspondingly short accretion timescales for black holes are reflected in the ages of jets which , for a sample of radio galaxies measured by @xcite , span a range from a few to 100myr . in seyfert galaxies the timescales are even shorter , as typified by ngc1068 for which @xcite estimate the age of the jets to be only @xmath4myr . that the putative causal connection between agn and starbursts might occur on relatively small spatial scales and short timescales can help us to understand why no correlation has been found between agn and ( circum-)nuclear starbursts in general . it is simply that the circumnuclear activity on scales greater than a few hundred parsecs is , in most cases , too far from the agn to influence it , or be strongly influenced by it ( cf * ? ? ? in this paper we redress this imbalance . while the optical spectroscopy pursued by many authors allows a detailed fitting of templates and models to the stellar features , we also make use of established star formation diagnostics and interpret them using starburst population synthesis models . observing at near infrared wavelengths has brought two important advantages . the optical depth is 10 times less than at optical wavelengths , and thus our data are less prone to the effects of extinction which can be significant in agn . and we have employed adaptive optics to reach spatial resolutions of 0.10.2 , bringing us closer to the nucleus . applying these techniques , we have already analysed the properties of the nuclear star formation in a few objects @xcite . here we bring those data together with new data on 5 additional objects . our sample enables us to probe star formation in agn from radii of 1kpc down to less than 10pc . our aim is to ascertain whether there is evidence for star formation on the smallest scales we can reach ; and if so , to constrain its star formation history . ultimately , we look at whether there are indications that the nuclear starburst and agn are mutually influencing each other .    in  [ sec : obs ] we describe the sample selection , observations , data reduction , psf estimation , and extraction of the emission and absorption line morphologies and kinematics . in  [ sec : diag ] we discuss the observational diagnostics and modelling tools . brief analyses of the relevant facets of our new data for the individual objects are provided in appendix  [ sec : obj ] , where we also summarise results of our previously published data , re - assessing them where necessary to ensure that all objects are analysed in a consistent manner . the primary aims of our paper are addressed in [ sec : prop ] and  [ sec : staragn ] . in  [ sec : prop ] we discuss global results concerning the existence and recent history of nuclear star formation for our whole sample . in [ sec : staragn ] we discuss the implications of nuclear starbursts on the starburst - agn connection . finally , we present our conclusions in  [ sec : conc ] . the agn discussed in this paper form a rather heterogeneous group . they include type  1 and type  2 seyferts , ulirgs , and even a qso , and do not constitute a complete sample . in order to maximise the size of the sample , we have combined objects on which we have already published adaptive optics near infrared spectra with new observations of additional targets . source selection was driven largely by technical considerations for the adaptive optics ( ao ) system , namely having a nucleus bright and compact enough to allow a good ao correction . this is actually a strength since it means that 7 of the 9 agn are in fact broad line objects  as given either by the standard type  1 classification or because there is clear broad ( fwhm @xmath5kms@xmath6 ) br@xmath7 emission in our spectra . [ fig : bbrg ] shows broad br@xmath7 in k - band spectra of 3 agn that are not usually classified as broad line galaxies . this is in contrast to most other samples of agn for which star formation has been studied in detail , and avoids any bias that might arise from selecting only type  2 syeferts . that there may be a bias arises from the increasing evidence that the obscuration in perhaps half of type  2 agn lies at kpc scales rather than in the nucleus , which may be caused by spatially extended star formation in the galaxy disk @xcite . such agn do not fit easily into the standard unification scheme ( and perhaps should not really be considered type  2 objects ) . because broad lines can be seen in the infrared , we know that we are seeing down to the nuclear region and hence our results are not subject to any effects that this might otherwise introduce . it is exactly broad line agn for which little is known about the nuclear star formation , because the glare of the agn swamps any surrounding stellar light in the central arcsec . as a result , most studies addressing star formation close to agn have focussed on type  2 seyferts . adaptive optics makes it possible to confine much of the agn s light into a very compact region , and to resolve the stellar continuum around it . the use of adaptive optics does give rise to one difficulty when attempting to quantify the results in a uniform way , due to the different resolutions achieved  which is a combination of both the distance to each object ( i.e. target selection ) and the ao performance . as a result , the standard deviation around the logarithmic mean resolution of our sample ( excluding ngc2992 , see section  [ sec : obj ] ) of 22pc is a factor of 3 . however , this has enabled us to study the centers of agn across nearly 3 orders of magnitude in spatial scale , from 1kpc in the more distant objects to only a few parsecs in the nearby objects with the best ao correction . a summary of our observations is given in table  [ tab : obs ] . a description of observations and processing of the new data is given below . data for iras05189 - 2524 and ngc1068 were taken in december 2002 at the vlt with naco , an adaptive optics near infrared camera and long slit spectrograph @xcite . since iras05189 - 2524 is nearly face on , there is no strongly preferred axis and the slit was oriented north - south ; for ngc1068 two orientations were used , north - south and east - west . in all cases the slit width was 0.086 , yielding a nominal resolution of @xmath8 with the wide - field camera ( pixel scale 0.054 ) and medium resolution grism . the galaxy was nodded back and forth along the slit by 10  to allow sky subtraction . for iras05189 - 2524 , 12 integrations of 300sec were made ; for ngc1068 12 integrations of 300sec were made at one position angle , and 14 frames of 200sec at the other . all data were reduced and combined , using standard longslit techniques in iraf , to make the final h - band spectrum . data for ngc7469 , ngc2992 , ngc1097 , ngc1068 , and ngc3783 were taken during 20042005 at the vlt with sinfoni , an adaptive optics near infrared integral field spectrograph @xcite . data were taken with various gratings covering the h and k bands either separately ( @xmath9 ) or together ( @xmath8 ) . the pixel scales were 0.125@xmath100.25  or 0.05@xmath100.1 , depending on the trade - offs between field of view , spatial resolution , and signal - to - noise ratio . individual exposure times are in the range 50300sec depending on the object brightness . object frames were interspersed with sky frames , usually using the sequence o - s - o - o - s - o , to facilitate background subtraction . the data were processed using the dedicated _ spred _ software package @xcite , which provides similar processing to that for longslit data but with the added ability to reconstruct the datacube . the data processing steps are as follows . the object frames are pre - processed by subtracting sky frames , flatfielding , and correcting bad pixels ( which are identified from dark frames and the flatfield ) . the wavemap is generated , and edges and curvature of the slitlets are traced , all from the arclamp frame . the arclamp frame is then reconstructed into a cube , which is checked to ensure that the calibration is good . the pre - processed object frames are then also reconstructed into cubes , spatially shifted to align them using the bright nucleus as a reference , and combined . in some cases the final cube was spatially smoothed using a @xmath11 median filter . estimation of the spatial resolution ( see below ) was always performed after this stage .    in some cases , the strong near - infrared oh lines did not subtract well . with longer exposure times this is to be expected since the timescale for variation of the oh is only 12mins . if visual inspection of the reconstructed cubes showed signs of over- or under - subtraction of the oh lines , these cubes were reprocessed using the method described in @xcite . standard star frames are similarly reconstructed into cubes . telluric correction and flux calibration were performed using b stars ( k - band ) or g2v stars ( h - band ) . in addition , flux calibration was cross - checked in 3  apertures using 2mass data , and in smaller 13  apertures using broad - band imaging from naco or hst nicmos . agreement between cubes with different pixel scales , and also with the external data , was consistent to typically 20% . there are a multitude of ways to derive the point spread function ( psf ) from adaptive optics data , five of which are described in @xcite . with agn , it is usually possible to estimate the psf from the science data itself , removing any uncertainty about spatial and temporal variations of the psf due to atmospheric effects . typically one or both of the following methods are employed on the new data presented here . if a broad emission line is detected , this will always yield a measure of the psf since the blr of seyfert galaxies has a diameter that can be measured in light days . alternatively , the non - stellar continuum will provide a sufficiently good approximation in all but the nearest agn since at near infrared wavelengths it is expected to originate from a region no more than 12pc across .    in every case we have fit an analytical function to the psf . since the strehl ratio achieved is relatively low , even a gaussian is a good representation . we have used a moffat function , which achieves a better fit because it also matches the rather broad wings that are a characteristic of partial adaptive optics correction . the psf measured for ngc3227 , which is shown in fig .  1 of @xcite , can be considered typical . if one applies the concept of ` core plus halo ' to this psf , then the gaussian fit would represent just the core while the moffat fit the entire ` core plus halo ' . integrating both of these functions indicates that about 75% of the flux is within the ` core ' , and it is thus this component which dominates the psf . in this paper , a more exact representation of the psf is not needed since we have not performed a detailed kinematic analysis , and we have simply used the moffat to derive a fwhm for the spatial resolution . the resolutions achieved are listed in table  [ tab : obs ] . the 2d distribution of emission and absorption features has been found by fitting a function to the continuum - subtracted spectral profile at each spatial position in the datacube . the function was a convolution of a gaussian with a spectrally unresolved template profile  in the case of emission lines it was an oh sky emission line , and for stellar absorption features we made use of template stars observed in the same configuration ( pixel scale and grism ) . a minimisation was performed in which the parameters of the gaussian were adjusted until the convolved profile best matched the data . during the minimisation , pixels in the data that consistently deviated strongly from the data were rejected . the uncertainties were boot - strapped using monte carlo techniques , assuming that the noise is uncorrelated and the intrinsic profile is well represented by a gaussian . the method involves adding a gaussian with the derived properties to a spectral segment that exhibits the same noise statistics as the data , and refitting the result to yield a new set of gaussian parameters . after repeating this 100 times , the standard deviation of the center and dispersion were used as the uncertainites for the velocity and line width . the kinematics were further processed using kinemetry @xcite . this is a parameterisation ( i.e. a mathematical rather than a physical model ) of the 2d field . as such , beam smearing is not a relevant issue to kinemetry , which yields an analytical expression for the observed data . of course , when the coefficients of this expression are interpreted or used to constrain a physical model , then beam smearing should be considered . mathematically , the kinemetry procedure fits the data with a linear sum of sines and cosines with various angular scalings around ellipses at each radius . we have used it for 3 purposes : to determine the best position angle and axis ratio for the velocity field , to remove high order noise from the raw kinematic extraction , and to recover the velocity and dispersion radial profiles . in all of the cases considered here , the kinematic centre of the velocity field was assumed to be coincident with the peak of the non - stellar continuum . in addition , the uniformity of the velocity field permitted us to make the simplifying assumption of a single position angle and axis ratio  i.e. there is no evidence for warps or twisted velocity contours . we then derived the position angle and inclination of the disk by minimising the _ a1 _ and _ b3 _ parameters respectively ( see @xcite for a description of these ) . the rotation curves were recovered by correcting the measured velocity profile for inclination . we have assumed throughout the paper that the dispersion is isotropic , and hence no inclination correction was applied to the dispersion that was measured . the innermost parts of the kinematics derived as above are of course still affected by beam smearing . in general , the central dispersion can not necessarily be taken at face value since it may either be artificially increased by any component of rotation included within the beam size , or decreased if neighbouring regions within the beam have a lower dispersion . in the galaxies we have studied , there are two aspects which mitigate this uncertainty : the rotation speed in the central region is much less than the dispersion and so will not significantly alter it ; and when estimating the central value we consider the trend of the dispersion from large radii , where the effect of the beam is small , to the center . for the basic analyses performed here , we have therefore adopted the central dispersion at face value . more detailed physical models for the nuclear disks , which properly account for the effects of beam smearing , will be presented in future publications . lastly , we emphasize that the impact of the finite beam size on the derived rotation curve does not affect our measurement of the dynamical mass . the reason is that , for all the dynamical mass estimates we make , the mass is estimated at a radius much large than the fwhm of the psf  as can be seen in the relevant figures . in this section we describe the tools of the trade used to analyse the data , and which lead us to the global results presented in section  [ sec : prop ] . specific details and analyses for individual objects can be found in appendix  [ sec : obj ] . we use the same methods and tools for all the objects to ensure that all the data are analysed in a consistent manner . perhaps the most important issue is how to isolate the stellar continuum , which is itself a powerful diagnostic . in addition , we use three standard and independent diagnostics to quantify the star formation history and intensity in the nuclei of these agn . these are the br@xmath7 equivalent width , supernova rate , and mass - to - light ratio . much of the discussion concerns how we take into account the contribution of the agn when quantifying these parameters . we also consider what impact an incorrect compensation could have on interpretation of the diagnostics . we model these observational diagnostics using the stellar population and spectral synthesis code stars ( e.g. * ? ? ? * ; * ? ? ? * ; * ? ? ? * ; * ? ? ? * ; * ? ? ? this code calculates the distribution of stars in the hertzsprung - russell diagram as a function of age for an assumed star formation history . we usually assume an exponentially decaying star formation rate , which has an associated timescale @xmath12 . spectral properties of the cluster are then computed given the stellar population present at any time . we note that the model output of stars is quantitatively similar to that from version 5.1 of starburst99 , which unlike earlier versions does include agb tracks @xcite . as discussed in detail below , particular predictions of stars include , for ages greater than 10myr : equivalent widths of @xmath13 and @xmath14 , and h - k color of 0.15mag . the equivalent quantities predicted by starburst99 v5.1 are @xmath15 and @xmath16 , and h - k color of 0.2mag .      for small observational apertures a significant fraction of the k - band ( and even h - band ) continuum can be associated with non - stellar agn continuum . the agn contribution can be estimated from a simple measurement of the equivalent width of a stellar absorption feature . we use co2 - 0 2.29  in the k - band or co6 - 3 1.62  in the h - band . although the equivalent widths @xmath17 and @xmath18 vary considerably for individual stars , the integrated values for stellar clusters span only a rather limited range . this was shown by @xcite who measured these values for elliptical , spiral , and star - forming ( hii ) galaxies . we have plotted their measurements of these two absorption features in the left - hand panel of fig . [ fig : equiv ] , together with the equivalent widths of giant and supergiant stars from @xcite .    in stars we use empirically determined equivalent widths from library spectra @xcite to compute the time - dependent equivalent width for an entire cluster of stars . results for various star formation histories are shown in the centre and right panels of fig . [ fig : equiv ] , for @xmath18 and @xmath17 respectively . typical values are @xmath19  and @xmath20 . the dashed box in the left panel shows that the locus of 20% deviation from each of these computed values is consistent with observations . that the hii galaxies have slightly higher @xmath17 can be understood because these are selected to have bright emission lines and hence are strongly biassed towards young stellar ages  often corresponding to the maximum depth of the stellar features that occurs at 10myr due to the late - type supergiant population . it may be this bias for galaxies selected as ` starbursts ' , and the similarity of the co depth for starbursts of all other ages , that led @xcite to conclude that there is no evidence for strong starbursts in seyfert2 galaxies . similarly , an estimate of the dilution can be found from the nai2.206  line . fig .  7 of @xcite shows that for nearly all star formation histories the value @xmath21 remains in the range 23 . our conclusion here is that within a reasonable uncertainty of @xmath2220% ( see fig . [ fig : equiv ] ) , one can assume that the intrinsic equivalent width of the absorption  most notably co  features of any stellar population that contains late - type stars is independent of the star formation history and age . for a stellar continuum diluted by additional non - stellar emission , the fraction of stellar light is @xmath23 where @xmath24 and @xmath25 are the observed and intrinsic equivalent widths of the co features discussed above . thus , we are able to correct the observed continuum magnitude for the contribution associated with the agn . our data cover both the h and k - bands  hence the reason for using both @xmath18 and @xmath17 . in order to homogenize the dataset , we need to convert h - band stellar magnitudes to k - band . the stars computation in fig .  [ fig : col_lum ] shows that this conversion is also independent of the star formation history , being close to @xmath26mag ( no extinction ) for all timescales and ages . this result is supported empirically by photometry of elliptical and spiral galaxies performed by @xcite . for ellipticals @xmath270.25 , and for spirals @xmath270.3 . some of the difference between the data and models could be due to extinction since @xmath28 ; and for @xmath29 , @xmath30 . however , at the level of precision required here , the 510% difference between model and data can be considered negligible .    to convert from absolute magnitude to luminosity we use the relation @xmath31 where @xmath32 is the total luminosity in the 1.92.5  band in units of bolometric solar luminosity ( @xmath33w ) , and as such different from the other frequently used monochromatic definition with units of the solar k - band luminosity density ( @xmath34w@xmath35m@xmath6 ) . we then use stars to estimate the bolometric stellar luminosity @xmath36 . the relation between @xmath36 and @xmath32 is shown in the right panel of fig . [ fig : col_lum ] . the dimensionless ratio @xmath37 depends on the age and the exponential decay timescale of the star formation . however , the range spanned is only 20200 for ages greater than 10myr . thus even if the star formation history can not be constrained , a conversion ratio of @xmath38 will have an associated uncertainty of only 0.3dex . in general we are able to apply constraints on the star formation age , and so our errors will be accordingly smaller . graphs showing how the diagnostics vary with age and star formation timescale are shown in fig . [ fig : stars ] . once the stellar continuum luminosity is known , an upper limit to the equivalent width of br@xmath7 asssociated with star formation can be found from the narrow br@xmath7 line flux . in some cases it is possible to estimate what fraction of the narrow br@xmath7 might be associated with the agn . this can be done both morphologically , for example if the line emission is extended along the galaxy s minor axis ; and/or kinematically , for example if the line shows regions that are broader , perhaps with fwhm a few hundred kms@xmath6 , suggestive of outflow . even if acounting for the agn contribution is not possible , one may be able to set interesting upper limits or even rule out continuous star formation scenarios , and put a constraint on the time since the star formation was active . this can be seen in the lefthand panel of fig . [ fig : stars ] , which shows for example that for ages less than @xmath39yrs , continuous star formation scenarios will always have @xmath40 . we estimate the type ii ( core collapse ) supernova rate @xmath41 from the radio continuum using the relation @xcite : @xmath42 where @xmath43 is the non - thermal radio continuum luminosity , @xmath44 is frequency of the observation and @xmath45 the spectral index of the non - thermal continuum . this relation was derived for galactic supernova remnants ; but a similar one , differing only in having a coefficient of @xmath46 , was derived by @xcite for m82 . for the 5ghz non - thermal radio continuum luminosity of arp220 ( 176mjy , * ? ? ? * ) it would lead to a supernova rate of 2.9yr@xmath6 , comfortably within the 1.753.5yr@xmath6 range estimated by @xcite based on the detection of individual luminous radio supernovae . this , therefore , seems a reasonable relation to apply to starbursts . we have to be careful , however , to take into account any contribution from the agn to the radio continuum . our premise for the nuclei of seyfert galaxies is that if the nuclear radio continuum is spatially resolved ( i.e. it has a low brightness temperature ) and does not have the morphology of a jet , it is likely to originate in extended star formation . at the spatial scales of a few parsec or more that we can resolve , emission from the agn will be very compact . as a result , we can use the peak surface brightness to estimate the maximum ( unresolved ) contribution from an agn . wherever possible , we use radio continuum observations at a comparable resolution to our data to derive the extended emission ; and observations at higher resolution to estimate the agn contribution . details of the data used in each case are given in the relevant sub - sections for each object in appendix  [ sec : obj ] . in addition , we exclude any emission obviously associated with jets , for example as in ngc1068 .    to use @xmath41 as a diagnostic , we normalise it with respect to the stellar k - band luminosity . this gives the ratio @xmath47 , for which stars output is drawn in fig . [ fig : stars ] . models indicate that the ratio @xmath48 of the stellar mass to k - band luminosity should be an excellent diagnostic since , for ages greater than 10myr , it increases monotonically with age as shown in fig .  [ fig : stars ] . however , in practice estimating the stellar mass is not entirely straightforward . in many cases it is only practicable to derive the dynamical mass . it may be possible to estimate and hence correct for the molecular gas mass based on millimetre co maps , but these are scarce at sufficiently high spatial resolution and are associated with their own co - to - h@xmath49 conversion uncertainties . we also note that it is often not possible to separate the ` old ' and ` young ' stellar populations . the best one can do is estimate the overall mass - to - light ratio , and argue that this is an upper limit to the true ratio for the young population . while there inevitably remains uncertainty on the true ratio , the limit is often sufficient to apply useful constraints on the age of the ` young ' population . our estimates of the dynamical mass are based wherever possible on the stellar kinematics , since the gas kinematics can be perturbed by warps , shocks , and outflows . we begin by estimating the simple keplerian mass assuming that the stars are supported by ordered rotation at velocity @xmath50 in a thin plane . however , the stellar kinematics in all the galaxies exhibit a significant velocity dispersion indicating that a considerable mass is supported by random rather than ordered motions . thus the simple keplerian mass is very much an underestimate , and any estimate of the actual mass is associated with large uncertainties  see for example @xcite , who derive masses of spheroidal systems . as stated in section  [ sec : obs ] , we assume that the random motions are isotropic . our relation for estimating the mass enclosed within a radius @xmath51 is then @xmath52 where @xmath53 is the observed 1-dimensional velocity dispersion . we note that when taking rotation into account in estimating the masses of spheroids with various density profiles , @xcite also use a factor 3 between the @xmath54 and @xmath53 terms in their appendix b. despite the complexities involved , within the unavoidable uncertainties ( a factor 23 ) , their relation gives the same mass as that above . although this uncertainty appears to be quite large , it does not impact the results and conclusions in this paper since we are concerned primarily with order - of - magnitude estimates when considering mass surface densities . in the following section we bring to together the individual results ( detailed in appendix  [ sec : obj ] ) to form a global picture . it is possible to do this because all the data have been analysed in a consistent manner , using the tools described in section  [ sec : diag ] to compare in each object the same diagnostics to the same set of stellar evolutionary synthesis models . we note that the discussion that follows is based on results for 8 of the agn we have observed . as explained in appendix  [ sec : obj ] we exclude ngc2992 because we are not able to put reliable constraints on the properties of the nuclear star formation . despite this , there are indications that at higher spatial resolution one should expect to find a distinct nuclear stellar population as has been seen in other agn . [ [ size - scale ] ] size scale + + + + + + + + + +    tracing the stellar features rather than the broad - band continuum , we have in all cases resolved a stellar population in the nucleus close around the agn . while this should not be unexpected if the stellar distribution follows a smooth @xmath55 or exponential profile , we have in several cases been able to show that on scales of @xmath56pc there is in fact an excess above what one would expect from these profiles . this suggests that in general we are probing an inner star forming component . [ fig : sizes ] shows normalised azimuthally averaged stellar luminosity profiles for the agn . these have not been corrected for a possible old underlying population , nor has any deconvolution with the psf been performed . nevertheless , it is still clear that the stellar intensity increases very steeply towards the nucleus . in 6 of the 8 galaxies shown , the half - width at half - maximum is less than 50pc . the remaining 2 galaxies are the most distant in the sample , and the spatial resolution achieved does not permit a size measurement on these scales . we may conclude that the physical radial size scale of the nuclear star forming regions in seyfert galaxies does not typically exceed 50pc .    [ [ stellar - age ] ] stellar age + + + + + + + + + + +    for 8 of the agn studied here , we have been able to use classical star formation diagnostics based on line and continuum fluxes as well as kinematics to constrain the ages of the inner star forming regions . the resulting ages should be considered ` characteristic ' , since in many cases there may simultaneously be two or more stellar populations that are not co - eval . for example , if a bulge population exists on these small spatial scales , it was not usually possible to account for the contamination it would introduce . while this would have little effect on @xmath57 , it could impact on @xmath58 more strongly , increasing the inferred age . the ages we find lie in the range 10300myr , compelling evidence that it is common for there to be relatively young star clusters close around agn . intriguingly , we also find rather low values of @xmath57 : typically @xmath59  ( see table  [ tab : derprop ] ) . this indicates directly that there is currently little or no on - going star formation . coupled with the relatively young ages , we conclude that the star formation episodes are short - lived . one may speculate then that the star formation is episodic , recurring in short bursts . the scale of the bursts and time interval between them would certainly have an impact on the fraction of seyfert nuclei in which observational programmes are able to find evidence for recent star formation . [ [ nuclear - stellar - disks ] ] nuclear stellar disks + + + + + + + + + + + + + + + + + + + + +    the first evidence for nuclear stellar disks came from seeing limited optical spectroscopy , for which a slight reduction in @xmath60 was seen for some spiral galaxies @xcite . and there is now a growing number of spiral galaxies  more than 30  in which the phenomenon has been observed , suggesting that they might occur in 30% or more of disk galaxies @xcite . the @xmath60-drop has been interpreted by @xcite as arising from a young stellar population that is born from a dynamically cold gas component , and which makes a significant contribution to the total luminosity . this appears to be borne out by n - body and sph simulations of isolated galaxies @xcite , which suggest that although the entire central system will slowly heat up with time , the @xmath60-drop can last for at least several hundred myr . indeed , preliminary analysis of optical integral field data for ngc3623 suggest that the stellar population responsible for the @xmath60-drop can not be younger than 1gyr @xcite . our results provide strong support for the nuclear disk interpretation . in previous work @xcite , we had argued that in both circinus and ngc3227 the inner distributions were disk - like , albeit thickened . we have now found much more direct evidence for this phenomenon in ngc1097 and ngc1068 . in both of these galaxies , we have spatially resolved a @xmath60-drop and an excess stellar continuum over the same size scales . in ngc1097 this size was @xmath610.5 , corresponding to about 40pc . for ngc1068 these effects were measured out to @xmath611 , equivalent to 70pc . these are not the scale lengths of the disks , but simply the maximum radius to which we can detect them . in both cases the mean mass surface densities are of order @xmath62(1 - 3)@xmath63m@xmath1pc@xmath2 . for an infinitely large thin self gravitating stellar disk , one can use the expression @xmath64 to estimate the scale height . although this may not be entirely appropriate , we use it here to obtain a rough approximation to the scale heights , which are 520pc . thus while the disks appear to be flattened , they should still be considered thick since the radial extent is only a few times the scale height . the impact of nuclear starbursts on the central light profile of galaxies was considered theoretically more than a decade ago by @xcite . they performed numerical simulations of galaxy mergers to study the mass and luminosity profiles of the remnants , taking gas into account , and estimating the star formation rate using a modified schmidt law . they found that there should be a starburst in the nucleus which would give rise to an excess stellar continuum above the @xmath55 profile of the older stars in the merged system . several years ago , compact nuclei were found to be present in a significant fraction of spiral galaxies @xcite as well as coma cluster dwarf ellipticals @xcite . more recently , nuclei with a median half - light radius of 4.2pc have been found in the majority of early - type members of the virgo cluster @xcite ; and traced out to @xmath611 , equivalent to @xmath65pc , in some of the ` wet ' merger remnants in that cluster @xcite . while the nuclear starbursts in these latter cases are caused by a merger event , whereas those we are studying arise from secular evolution as gas from the galaxy disk accretes in the nucleus , there appear to be many parallels in the phenomenology of the resulting starbursts . [ [ star - formation - rate ] ] star formation rate + + + + + + + + + + + + + + + + + + +    it is possible to estimate the bolometric luminosity @xmath66 of the stars from their k - band luminosity @xmath67 even if one knows nothing about the star formation history . as discussed in section  [ sec : diag ] , this would result in an uncertainty of about a factor 3 . the diagnostics in table  [ tab : derprop ] and discussions in appendix  [ sec : obj ] enable us to apply some constraints to the characteristic age of the star formation . because continuous star formation is ruled out by the low @xmath57 , we have assumed exponential decay timescales of @xmath68100myr . we have then used stars to estimate the average star formation rates . in order to allow a meaningful comparison between the objects , the rates have been normalised to the same area of 1kpc@xmath69 . these are the rates given in table  [ tab : derprop ] . they are calculated simply as the mass of stars produced divided by the entire time since the star forming episode began . because @xmath12 is shorter than the age , the average includes both active and non - active phases of the starburst . indeed , for @xmath68myr one would expect the star formation rate during the active phases to be at least a factor of a few , and perhaps an order of magnitude , greater . the table shows that on scales of a few hundred parsecs one might expect a few @xmath70m@xmath1yr@xmath6kpc@xmath2 , while on scales of a few tens of parsecs mean rates reaching @xmath65m@xmath1yr@xmath6kpc@xmath2 should not be unexpected ; and correspondingly higher  up to an order of magnitude , see fig . [ fig : starstoy ]  during active phases . an obvious question is why there should be such vigorous star formation in these regions . star formation rates of 10100m@xmath1yr@xmath6kpc@xmath2 are orders of magnitude above those in normal galaxies and comparable to starburst galaxies . the answer may lie in the schmidt law and the mass surface densities we have estimated in table  [ tab : derprop ] . [ fig : msurfden ] shows these surface densities at the radii over which they were estimated , revealing a trend towards higher densities on smaller scales and values of a few times @xmath71m@xmath1pc@xmath2 in the central few tens of parsecs . the global schmidt law , as formulated by @xcite , states that the star formation rate depends on the gas surface density as @xmath72 . if one assumes that 1030% of the mass in our agn is gas , then this relation would predict time - averaged star formation rates in the range 10100m@xmath1yr@xmath6kpc@xmath2 , as have been observed . that the high star formation rates may simply be a consequence of the high mass surface densities is explored futher by hicks et al . ( in prep . ) . [ [ stellar - luminosity ] ] stellar luminosity + + + + + + + + + + + + + + + + + +    as a consequence of the high star formation rates , the stellar luminosity per unit area close around the agn is very high in these objects . despite this , because the star formation is occurring only in very small regions , the absolute luminosities are rather modest . this can be seen in fig . [ fig : mag_agn ] which shows the bolometric luminosity of the stars as a fraction of the entire bolometric luminosity of the galaxy . we have calculated a range for the ratio @xmath73 appropriate for each galaxy based on the ages in table  [ tab : derprop ] for different @xmath12 . because we assume that all the k - band stellar continuum is associated with the young stars , we have adopted the lower end of each range in an attempt to minimise possible overestimation of @xmath66 . the resulting values for the ratio used span 30130 , within a factor of 2 of the ` baseline ' value of 60 given in section  [ sec : diag ] . in the central few tens of parsecs , young stars contribute a few percent of the total . but integrated over size scales of a few hundred parsecs , this fraction can increase to more than 20% . on these scales , the star formation is energetically significant when compared to the agn . such high fractions imply that on the larger scales the extinction to the young stars must be relatively low . on the other hand , on the smallest scales where in absolute terms the stellar luminosity is small , there could in general be considerable extinction even at near infrared wavelengths . in this paper we have not tried to account for extinction since it is very uncertain . the primary effect of doing so would simply be to increase the stellar luminosity above the values discussed here . [ fig : mag_bol ] shows the stellar bolometric luminosity @xmath66 integrated as a function of radius . all the curves follow approximately the same trend , with the luminosity per unit area increasing towards smaller scales and approaching @xmath74l@xmath1kpc@xmath2 in the central few parsecs . this appears to be a robust trend and will not change significantly even with large uncertainties of a factor of a few . it is remarkable that the luminosity density of @xmath74l@xmath1kpc@xmath2 is that estimated by @xcite for ulirgs , which they modelled as optically thick starburst disks . the main difference between the ulirg model and the starbursts close around agn is the spatial scales on which the starburst occurs . based on this model , they argued that ulirgs are radiating at the eddington limit for a starburst , defined as when the radiation pressure on the gas and dust begins to dominate over self - gravity . the limiting luminosity - to - mass ratio was estimated to be @xmath75l@xmath1/m@xmath1 by @xcite . he argued that in a star cluster , once the upper end of the main sequence was populated , the radiation pressure would halt further accretion on to the star cluster and hence terminate the star formation . following @xcite , we apply this definition to the entire disk rather than a single star cluster . for the @xmath74l@xmath1kpc@xmath2 , this implies a mass surface density of @xmath76m@xmath1pc@xmath2 . comparing these quantities to the agn we have observed , we find that on scales of a few tens of parsecs they are an order of magnitude below the eddington limit . on the other hand , we have already seen that the low @xmath57 indicates that there is little on - going star formation and hence that the starbursts are short - lived . this is important because short - lived starbursts fade very quickly . as shown in fig . [ fig : starstoy ] , for a decay timescale of @xmath68myr , @xmath66 will have decreased from its peak value by more than an order of magnitude at an age of 100myr . thus it is plausible  and probably likely  that while the star formation was active , the stellar luminosity was an order of magnitude higher . in this case the starbursts would have been at , or close to , their eddington limit at that time . the luminosity - to - mass ratio of @xmath77l@xmath1/m@xmath1 associated with the eddington limit is in fact one that all young starbursts would exceed if , beginning with nothing , gas was accreted at the same rate that it was converted into stars . that , however , is not a realistic situation . a more likely scenario , shown in fig . [ fig : ratio_bol ] , is that the gas is already there in the disk . in this case , a starburst with a star - forming timescale of 100myr could never exceed @xmath78l@xmath1/m@xmath1 . to reach @xmath77l@xmath1/m@xmath1 , the gas would need to be converted into stars on a timescale @xmath79myr . this timescale is independent of how much gas there is . thus , for a starburst to reach its eddington limit , it must be very efficient , converting a significant fraction of its gas into stars on very short @xmath80myr timescales . this result is consistent with the prediction of the schmidt law , which states that disks with a higher gas surface density will form stars more efficiently . the reason is that the star formation efficiency is simply @xmath81 . thus , from arguments based solely on the schmidt law and mass surface density , one reaches the same conclusion that the gas supply would be used rather quickly and the lifetime of the starburst would be relatively short . summarising the results above , a plausible scenario could be as follows . the high gas density leads to a high star formation rate , producing a starburst that reaches its eddington limit for a short time . because the efficiency is high , the starburst can only be active for a short time and then begins to fade . inevitably , one would expect that the starburst is then dormant until the gas supply is replenished by inflow . this picture appears to be borne out by the observations presented here . in the previous sections we have presented and discussed evidence that in general there appears to have been moderately recent star formation on small spatial scales around all the agn we have observed . [ fig : age ] shows the first empirical indication of a deeper relationship between the star formation and the agn . in this figure we show the luminosity of the agn , both in absolute units of solar luminosity and also in relative units of its eddington luminosity @xmath82 , against the age of the most recent known nuclear star forming episode . since the agn luminosity is not well known , we have made the conservative assumption that it is equal to half the bolometric luminosity of the galaxy  as may be the case for ngc1068 ( @xcite , but see also @xcite ) . to indicate the expected degree of uncertainty in this assertion we have imposed errorbars of a factor 2 in either direction , equivalent to stating that the agn luminosity in these specific objects is likely to be in the range 25100% of the total luminosity of the galaxy . the eddington luminosity is calculated directly from the black hole mass , for which estimates exist for these galaxies from reverberation mapping , the m@xmath83 relation , maser kinematics , etc . these are listed in table  [ tab : basicdata ] . for the age of the star formation , we have plotted the time since the most recent known episode of star formation began , as given in table  [ tab : derprop ] . for galaxies where a range of ages is given , we have adopted these to indicate the uncertainty ; the mean of these , @xmath8430% , has been used to estimate the uncertainty in the age for the rest of the galaxies . we note that these errorbars reflect uncertainties in characterising the age of the star formation from the available diagnostics and also in the star formation timescale @xmath12 . however , there are still many implicit assumptions in this process , and we therefore caution that the actual errors in our estimation of the starburst ages may be larger than that shown .    conceding this , we do not wish to over - interpret the figure . keeping the uncertainties in mind , fig . [ fig : age ] shows the remarkable result that agn which are radiating at lower efficiency @xmath85l / l@xmath86 are associated with younger @xmath87100myr starbursts ; while those which are more efficient @xmath88l / l@xmath86 have older @xmath89100myr starbursts . if one were to add to this figure the galactic centre  which is known to have an extremely low luminosity ( l / l@xmath90 ; @xcite ) and to have experienced a starburst @xmath91myr ago @xcite  it would be consistent with the categories above . the inference is that either there is a delay between the onset of starburst activity and the onset of agn activity , or star formation is quenched once the black hole has become active .    in section  [ sec : prop ] we argued that the starbursts are to some extent self - quenching : that very high star formation efficiencies are not sustainable over long periods . in addition , an intense starburst will provide significant heat input to the gas , which is perhaps partially responsible for the typically high gas velocity dispersions in these regions ( hicks et al . , in prep . ) . this itself could help suppress further star formation . heating by the agn could also contribute to this process , and has been proposed as the reason why the molecular torus is geometrically thick @xcite . it is also used to modulate star formation ( at least on global scales ) in semi - analytic models of galaxy evolution @xcite . while this is certainly plausible , it does not explain either why the star formation in some galaxies with a lower luminosity agn has already ceased , nor why none of the agn associated with younger starbursts are accreting efficiently . instead we argue for the former case above , that efficient fuelling of a black hole is associated with a starburst that is at least 50100myr old . it may be because of such a delay between agn and starburst activity that recent star formation is often hard to detect close to agn : the starburst has passed its most luminous ( very young ) age , and is in decline while the agn is in its most active phase ( see fig . [ fig : starstoy ] ) . this does not necessarily imply that the _ a priori _ presence of a starburst is required before an agn can accrete gas  although it seems inevitable that one will occur as gas accumulates in the nucleus . nor does it imply that all starbursts will result in fuelling a black hole ; indeed it is clear that there are many starbursts not associated with agn . as we argue below , the crucial aspect may be the stellar ejecta associated with the starburst ; and in particular , not just the mass loss rate , but the speed with which the mass is ejected . [ [ winds - from - ob - stars ] ] winds from ob stars + + + + + + + + + + + + + + + + + + +    in the galactic center , @xcite proposed that it is the recent starburst there that is limiting the luminosity of the black hole . in this scenario , mechanical winds from young stars  both the outflow and the angular momentum of the gas ( which is a consequence of the angular momentum of the stars themselves )  hinder further inflow . the authors argued that almost none of the gas flowing into the central parsec reached the black hole because of outflowing winds from irs16 and hei stars in that region . detailed modelling of the galactic center region as a 2-phase medium was recently performed by @xcite . they included both the fast young stellar winds with velocities of 700kms@xmath6 @xcite and the slower winds of @xmath92kms@xmath6 @xcite ; and also took into account the orbital angular momentum of the stars @xcite , which had a strong influence on reducing the accretion rate . they found that the average accretion rate onto the black hole was only @xmath93m@xmath1yr@xmath6 , although an intermittent cold flow superimposed considerable variability onto this . in contrast , the hypothetical luminosity @xcite estimate that sgra@xmath94 would have if it could accrete all the inflowing gas , would be @xmath95ergs@xmath6 , typical of seyfert galaxies . in principle this process could be operating in other galaxy nuclei where there has been a starburst which extends to less than 1pc from the central black hole . however , it can not explain the timescale of the delay we have observed , which is an order of magnitude greater than the main sequence lifetime of ob and wolf - rayet stars .    [ [ winds - from - agb - stars ] ] winds from agb stars + + + + + + + + + + + + + + + + + + + +    stars of a few ( 18m@xmath1 ) solar masses will evolve on to the asymptotic giant branch ( agb ) at the end of their main sequence lifetimes . the timescale for stars at the upper end of this range to reach this phase is @xmath96myr , comparable to the delay apparent in fig . [ fig : mag_bol ] . since agb stars are known to have high mass - loss rates , of order @xmath97@xmath98m@xmath1yr@xmath6 at velocities of 1030kms@xmath6 @xcite , they may be prime candidates for explaining the delay between starburst and agn activity . to quantify this , we consider how much of the mass in the wind could be accreted by the central supermassive black hole . the bondi parameterisation of the accretion rate onto a point particle for a uniform spherically symmetric geometry is given by @xcite @xmath99 where @xmath100 is the mass of the point particle moving through a gas cloud , @xmath54 is the velocity of the particle with respect to the cloud , @xmath101 is the density of the cloud far from the point particle , and @xmath102 is the sound speed . this approximation is still used to quantify accretion on to supermassive black holes in models of galaxy evolution @xcite , even though it may be significantly inaccurate for realistic ( e.g. turbulent ) media @xcite . here , it is sufficient to provide an indication of the role that stellar winds may play in accretion onto a central black hole . the density of the stellar wind at a distance @xmath51 from the parent star is given by @xmath103 in our case , @xmath51 is the distance from the star to the black hole . one would therefore expect that the accretion rate on to the black hole could be written as ( see also @xcite ) @xmath104 this equation shows that @xmath105 . we have implicitly assumed that @xmath106 is greater than the orbital velocity @xmath107 of the star from which it originates . this is not the case for agb winds , and so one reaches the limiting case of @xmath108 , where for the galaxies we have observed @xmath109100kms@xmath6 . this is still at least an order of magnitude less than the winds from ob and wolf - rayet stars . thus , even though the mass loss rates from individual ob and wolf - rayet stars are similar to those of agb stars , the agb winds will fuel a black hole much more efficiently . however , for slow stellar winds that originate close to a @xmath110m@xmath1 black hole , the equation breaks down because the conditions of uniformity and spherically symmetry are strongly violated . indeed , the apparent accretion rate exceeds the outflow rate  implying that essentially the entire wind can be accreted . for agb wind velocities of 1030kms@xmath6 , the maximum radius at which the entire wind from a star in keplerian orbit around a @xmath110m@xmath1 black hole will not exceed the escape velocity from that orbit ( i.e. @xmath111 ) is around 1070pc . we adopt the middle of this range , 40pc , as the characteristic radius within which it is likely that a significant fraction , and perhaps most , of the agb winds are accreted onto the black hole . [ fig : mag_bol ] indicates that the stellar luminosity within this radius is @xmath112l@xmath1 . it is this luminosity that has been used to scale the stars model ( for @xmath68myr and an age of 100myr ) in fig . [ fig : starstoy ] , and so one can also simply read off the mass loss from the figure . the mass loss rate for such winds peaks at about 0.1m@xmath1yr@xmath6 and then tails off proportionally to the k - band luminosity , leading to a cumulative mass lost of @xmath113m@xmath1 after 1gyr ( although most of the loss occurs actually occurs within half of this timespan ) . this mass loss rate is sufficient to power a seyfert nucleus for a short time . a typical seyfert with m@xmath114m@xmath1 requires 0.02m@xmath1yr@xmath6 to radiate at the eddington limit . even for the short bursts we have modelled , fig . [ fig : starstoy ] shows that this can be supplied by agb winds for starburst ages in the range 50200myrs . we note that taking an agb star luminosity of @xmath71l@xmath1 ( which is at the high end of the likely average , @xcite ) we then find that there are @xmath115 agb stars close enough to the black hole to contribute to accretion . in order to provide at least 0.02m@xmath1yr@xmath6 , the typical mass loss rate per star must exceed @xmath97m@xmath1yr@xmath6 , which is the lower limit of the range measured for galactic agb stars given above . thus the mass losses and rates estimated here appear to be plausible . the low speed of these winds means they will not create much turbulence . we quantify this by considering their total mechanical energy @xmath116 integrated over the same timespan , which is @xmath117j . these two quantities  gas mass ejected and mechanical energy  are compared to those for supernovae below . [ [ supernovae ] ] supernovae + + + + + + + + + +    type ii supernovae are the stellar outflows most able to create turbulence in the interstellar medium , since they typically eject masses of @xmath118m@xmath1 at velocities of @xmath119kms@xmath6 @xcite . each supernova therefore represents a considerable injection of mechanical momentum and energy into the local environment . a large number of compact supernova remnants are known , for example in m82 and arp220 , and are believed to have expanded into dense regions with @xmath120@xmath71@xmath121 @xcite . these authors argue that such remnants become radiative when they reach sizes of @xmath122pc , at which point the predicted expansion velocity will have slowed to @xmath75kms@xmath6 . by this time , the shock front will have driven across @xmath123m@xmath1 of gas . when integrated over the age of the starburst , even for low supernova rates e.g. the current rate within 30pc of the nucleus of ngc3227 is @xmath124yr@xmath6 @xcite  this represents a substantial mass of gas that has been affected by supernova remnants . the stars model we have constructed in fig .  [ fig : starstoy ] indicates that typically one could expect @xmath125 supernovae to occur as a result of one of the short - lived starbursts ; and that most of these will occur around 1050myr after the beginning of the starburst . for a decay timescale of the star formation rate that is longer than @xmath68myr , this timespan will increase . hence , supernovae may also play a role in causing the observed delay between starburst and agn activity . stars calculates the mass loss and mass loss rates using a very simple scheme , assuming that a star ejects all of its lost mass at the end of its life on a stellar track . thus , it does not calculate the mass lost from supernovae explicitly , rather the combined mass lost from ob winds and supernovae which is much higher . we therefore adopt the @xmath118m@xmath1 per supernova given above , which yields a total ejected mass of @xmath126m@xmath1 . this is about 40% of that released by agb winds . however , since this gas is ejected at high speed and @xmath105 , the efficiency with which it can be accreted onto the black hole is extremely low . this can also be seen in the total mechanical energy of @xmath127j , which is several orders of magnitude greater than for agb winds . in fact the total mechanical energy exceeds the binding energy of the nuclear region , which is of order @xmath128j ( assuming @xmath129m@xmath1 within 40pc ) . as a result , it is highly likely that supernova cause some fraction of the gas to be permanently expelled . indeed , superwinds driven by starbursts are well known in many galaxies . this is not important as long as sufficient gas either remains to fuel the agn , or more is produced by stellar winds  which , as we have argued above , appears to be the case for agb stars . we have obtained near infrared spectra of 9 nearby active galactic nuclei using adaptive optics to achive high spatial resolution ( in several cases better than 10pc ) . for 7 of these , integral field spectroscopy with sinfoni allows us to reconstruct the full 2-dimensional distributions and kinematics of the stars and gas . although the individual agn are very varied , we have analysed them in a consistent fashion to derive : the stellar k - band luminosity , the dynamical mass , and the equivalent width of the br@xmath7 line . we have combined these with radio continuum data from the literature , which has been used to estimate the supernova rate . we have used these diagnostics to constrain stars evolutionary synthesis models and hence characterize the star formation timescales and ages of the starbursts close around agn . our main conclusions can be summarised as follows :    * the stellar light profiles show a bright nuclear component with a half - width at half - maximum of less than 50pc . in a number of cases these nuclear components clearly stand out above an inward extrapolation of the profile measured on larger scales . in addition , there are 2 cases which show kinematical evidence for a distinct stellar component , indicating that the nuclear stellar populations most probably exist in thick nuclear disks . the mean mass surface densities of these disks exceeds @xmath71m@xmath1pc@xmath2 . * there is abundant evidence for recent star formation in the last 10300myr . but the starbursts are no longer active , implying that the star formation timescale is short , of order a few tens of myr . while the starbursts were active , the star formation rates would have been much higher than the current rates , reaching as high as 1000m@xmath1kpc@xmath2 in the central few tens of parsecs ( comparable to ulirgs , but on smaller spatial scales ) . these starbursts would have been eddington limited . due to the very high star forming efficiency , the starbursts would have also exhausted their fuel supply on a short timescale and hence have been short - lived . it therefore seems likely that nuclear starbursts are episodic in nature . * there appears to be a delay of 50100myr ( and in some cases perhaps more ) between the onset of star formation and the onset of agn activity . we have interpreted this as indicating that the starburst has a significant impact on fuelling the central black hole , and have considered whether outflows from stars might be responsible . while supernovae and winds from ob stars eject a large mass of gas , the high velocity of this gas means that its accretion efficiency is extremely low . on the other hand , winds from agb stars ultimately dominate the total mass ejected in a starburst ; and the very slow velocities of these winds mean they can be accreted onto the black hole very efficiently . the authors thank all those who assisted in the observations , and also the referee for a thorough review of the paper . this work was started at the kavli institute for theoretical physics at santa barabara and as a result was supported in part by the national science foundation under grant no . phy05 - 51164 . rd aknowledges the interesting and useful discussions he had there with eliot quartaert , norm murray , julian krolik and todd thompson . _ facilities : _ , . this appendix contains specific details on the individual objects . we summarize our published results from near infrared adaptive optics spectroscopy of individual objects , and present a brief analysis of the new data for several other objects . the aim of re - assessing the data for mkn231 that has already been published is to ensure that it is analysed using stars in a manner that is consistent with the new data . for ngc7469 , we make a significant update of the analysis using new data from integral field spectroscopy . in general , for objects with new data , we provide only the part of the analysis relevant to understanding star formation around the agn . our intention is that a complete analysis for each object will be presented in future publications . our analyses are restricted to the nuclear region . since there is no strict universal definition of what comprises the ` nuclear region ' , we explicitly state in table  [ tab : derprop ] the size of the region we study in each galaxy . the table also presents a summary of the primary diagnostics . the way in which these have been derived , and their likely uncertainties , has been discussed in some detail already in section  [ sec : diag ] . as such , the description of these methods is not repeated , and in this section we discuss only issues that require special attention . a detailed analysis of the star formation in the nucleus of mkn231 at a resolution of about 0.18  ( 150pc ) was given in @xcite . here we summarize only the main points ; no new data is presented , but the analysis is updated using stars to make it consistent with the other objects studied in this paper . the presence of stellar absorption features across the nucleus demonstrates the existence of a significant population of stars . the radial distribution and kinematics indicate they lie , like the gas @xcite , in a nearly face - on disk . @xcite found that the dynamical mass imposed a strong constraint on the range of acceptable starburst models , yielding an upper limit to the age of the stars of around 120myr . re - assessing the mass - to - light ratio using stars models suggests that for the increased mass required by a more face - on orientation ( @xmath130 ) an upper age of 250myr is also possible , depending on the star formation timescale . however , either a small change of only a few degrees to the inclination ( to @xmath131 ) , or a relatively short star formation timescale of 10myr would reduce the limit to the @xmath61100myr previously estimated . this is more consistent with the extremely high supernova rate . the stellar luminosity , found from the dilution of the co absorption @xcite , indicates that stars within 1  ( 800pc ) of the nucleus contribute 2540% of the bolometric luminosity of the galaxy . similarly , within 200pc , stars comprise 1015% of l@xmath132 . the age , star formation rate , and size scale ( disk scale length of 0.180.2 ) are all consistent with high resolution radio continuum imaging @xcite . star formation in the central 16pc of circinus was addressed by @xcite . the diagnostics given in table  [ tab : derprop ] are taken from this reference . we used the depth of the co2 - 0 bandhead to estimate the stellar luminosity , combined with the narrow br@xmath7 flux ( which we argued originated in star forming regions rather than the agn narrow line region ) and the radio continuum , to constrain starburst models . the conclusion was that the starburst was less than 80myr old and was already decaying . on these scales it contributes 1.4% of l@xmath132 , or more if extinction is considered . a similar nuclear star formation intensity was estimated by @xcite , who were also able to study circinus on larger scales . they found that the luminosity of young stars within 200pc of the agn was of order @xmath133@xmath134 , and hence comparable to the agn . an analysis similar to that for circinus was performed on ngc3227 by @xcite , and the diagnostics given in table  [ tab : derprop ] are taken from this reference . in this case we were able to make estimates of and correct for contributions of : ( 1 ) the narrow line region to br@xmath7 , because there were clear regions along the minor axis that had higher dispersion ; ( 2 ) the agn to the radio continuum , by estimating the maximum contribution from an unresolved source ; and ( 3 ) the bulge stars to the stellar luminosity , by extrapolating the radial profile of the bulge to the inner regions . the stars models yielded the result that in the nucleus , star formation began approximately 40myr ago and must have already ceased . at the resolution of 0.085 , the most compact component of stellar continuum had a measured fwhm of 0.17 , suggesting an intrinsic size scale of @xmath135pc . young stars within 30pc of the agn ( i.e. more than just the most compact region ) have a luminosity of @xmath136@xmath134 , which is @xmath137% of the entire galaxy .        star formation on large scales in ngc7469 has been studied by @xcite . they found that within 800pc of the nucleus , a region that includes the circumnuclear ring , the luminosity from young stars was @xmath138@xmath134 , about 70% of the galaxy s bolometric luminosity . this situation is similar to that in mkn231 . on smaller scales , the nuclear star formation in ngc7469 was directly resolved by @xcite on a size scale of 0.150.20  ( 5065pc ) fwhm . an analysis of the longslit data , similar to that for mkn231 , was made  making use of stellar absorption features , kinematics , and starburst models . we estimated that the age of this region was no more than 60myr under the assumption that the fraction of stellar light in the k - band in the central 0.2  was 2030% . our new integral field sinfoni observations of ngc7469 at a spatial resolution of 0.15  ( measured from both the broad br@xmath7 and the non - stellar continuum profiles , see section  [ sec : obs ] ) are used here to make a more accurate estimate of the nuclear k - band luminosity . they enable us to provide a short update to the detailed analysis in @xcite . the sinfoni data show that the equivalent width of the 2.3  co2 - 0 is @xmath139  in a 0.8  aperture and 0.9  in a 0.2  aperture . the corresponding k - band magnitudes are @xmath140 and @xmath141 respectively . if one takes the intrinsic equivalent width of the 2.3  co2 - 0 bandhead to be 12  ( see section  [ sec : diag ] ) , one arrives at a more modest value of 8% for the stellar fraction of k - band continuum in the 0.2aperture . the stellar k - band luminosity in this region is then @xmath142l@xmath1 . comparing this to the dynamical mass in @xcite yields a mass - to - light ratio of m / l@xmath143m@xmath1/l@xmath1 . previously , extrapolation from a 37mas slit to a filled aperture had led to an underestimation of the total magnitude but an overestimation of the stellar contribution . fortuitously , these uncertainties had compensated each other . the same analysis for the 0.8  aperture yields a k - band stellar luminosity of @xmath144l@xmath1 and hence m / l@xmath145m@xmath1/l@xmath1 . the k - band datacube yields estimates of the upper limit to @xmath57 of 17  and 11  in 0.2  and 0.8apertures respectively . this has been corrected for dilution of the stellar continuum ( as described in section  [ sec : diag ] ) but not for a possible contribution to the narrow br@xmath7 from the agn . hence the actual @xmath57 corresponding to only the stellar line and continuum emission will be less than these values  indicating that the star formation is unlikely still to be on - going . we estimate the age of the star formation using the stars models in fig .  [ fig : stars ] . within the 0.2  aperture this gives 100myr , comparable to our original estimate . such a young age is supported by radio continuum measurements . with a 0.2  beam , @xcite reported that the unresolved core flux in ngc7469 was 12mjy at 8.4ghz . with much higher spatial resolution of 0.03 , @xcite reported an upper limit to the unresolved 8.4ghz continuum of 7mjy . we assume that the difference of 5mjy is due to emission extended on scales of 1060pc which is resolved out of one beam but not the other . as discussed in section  [ sec : diag ] , star formation is a likely candidate for such emission . in this case , we would estimate the supernova rate to be @xmath4yr@xmath6 and the ratio @xmath146 . this is likely to be a lower limit since there was only an upper limit on the core radio flux density . for a ratio of this order , even allowing for some uncertainty , fig  [ fig : stars ] implies an age consistent with no more than 100myr .    within the 0.8  aperture , which we adopt in table  [ tab : derprop ] , continuous star formation is inconsistent with w@xmath147 . for a star formation timescale of @xmath148myr , the mass - to - light ratio implies an age of 190myr , just consistent with the measured value of w@xmath149 . if some of the narrow br@xmath7 is associated with the agn rather than star formation , then a shorter star formation timescale is required . for @xmath68myr , the ratio m / l@xmath150 yields an age of 110myr . [ fig : ir05189_spec ] shows the h - band spectrum integrated across two segments of the naco slit , located on either side of the nucleus . it shows that even away from the nucleus , the depth of the stellar absorption features is only a few percent . we have therefore decomposed the data into the stellar and non - stellar parts using both the stellar absorption features and the spectral slope of the continuum . the latter method has been shown to work for well sampled data by @xcite . the rationale is that the hot dust associated with the agn will be much redder than the stellar continuum . an agn component is also expected to be unresolved for a galaxy at the distance ( 170mpc ) of iras05189 - 2524 . the spectral slope was determined by fitting a linear function to the spectrum at each spatial position along the slit . it is plotted as a function of position in fig . [ fig : ir05189_decomp ] , showing a single narrow peak . a gaussian fit to this yields a spatial resolution of 0.12  ( 100pc ) fwhm . the stellar continuum , also shown in fig . [ fig : ir05189_decomp ] , has been determined by summing the four most prominent absorption features : co4 - 1 , sii , co5 - 2 , co6 - 3 . while a gaussian is not an optimal fit to this profile , it does yield an aproximate size scale , which we find to be 0.27  fwhm . quadrature correction with the spatial resolution yields an intrinsic size of 0.25  ( 200pc ) . as a cross - check , in the figure we have compared the sum of these two components to the full continuum profile . the good match indicates that the decomposition appears to be reasonable . remarkably , the 200pc size of the nuclear stellar light is very similar to that of the 8.44ghz radio continuum map of @xcite . with a beam size of 0.50@xmath100.25 , they resolved the nuclear component to have an intrinsic size of 0.20@xmath100.17 . in constrast to radio sources which are powered by agn and have brightness temperatures @xmath151k , the emission here is resolved and has a low brightness temperature of @xmath152k . this implies a star forming origin . using their scaling relations further suggests that the flux density corresponds to a supernova rate of @xmath122yr@xmath6 . as described in section  [ sec : diag ] , we have estimated the stellar luminosity by comparing the h - band spectrum to a template star to correct for dilution . we used hr8465 a k1.5i star for which the equivalent width of co6 - 3 is 4.2 , within the 45  range predicted by stars in fig . [ fig : equiv ] . by extrapolating from the spatial profiles along the slit we have estimated the integrated equivalent width within a 1.1  aperture , for which @xcite gave an h - band magnitude of 11.83 . using all four features above we find for the template @xmath153  and for iras05189 - 2524 @xmath154 . this implies that in the central 1.1 , approximately 45% of the h - band continuum originates in stars . using the colour conversion @xmath26 from fig .  [ fig : col_lum ] ( see section  [ sec : diag ] ) we find a k - band magnitude for the stars of 12.55mag and hence a k - band stellar luminosity of @xmath155l@xmath1 . putting these results together we derive a ratio of supernova rate to k - band stellar luminosity of @xmath156 / l_{k } [ 10^{10 } l_\odot ] \sim 5 $ ] . applying corrections for extinction and an agn contribution would tend to decrease this ratio .    as a second diagnostic we use @xmath57 . we estimate the dilution of the k - band continuum via two methods . firstly , we measure @xmath157 , indicating a stellar fraction of 0.100.15 . a consistency check is provided by the h - band dilution , which we extrapolate to the k - band using blackbody functions for the stars and dust assuming characteristic temperatures of 5000k and 1000k respectively . this method suggests the k - band stellar fraction is around @xmath158 . hence correcting the directly measured equivalent width of the narrow br@xmath7 for the non - stellar continuum yields @xmath1595 .    since iras05189 - 2524 is close to face - on @xcite , it is not straightforward to make a reliable estimate of the dynamical mass . nevertheless , requiring @xmath160 to be high while @xmath57 is low already puts significant constraints on the star formation history . thus , although the star formation has probably ended , the age is unlikely to be greater than 100myr , and could be as low as 50myr where @xmath160 peaks . for such ages the ratio @xmath37 is in the range 100150 . hence for the young stars within 0.55  ( 450pc ) of the nucleus we find @xmath16123@xmath162l@xmath1 , about 20% of @xmath36 for the galaxy . the spatial resolution of the k - band data for ngc2992 has been estimated from both the broad br@xmath7 and the non - stellar continuum ( see section  [ sec : obs ] and  [ sec : diag ] ) . the two methods yield symmetric psfs , with fwhms of 0.32  and 0.29  respectively , corresponding to 50pc .      unlike iras05189 - 2524 , the radio continuum in ngc2992 is quite complex . much of the extended emission on scales of a few arcsec appears to originate from a superbubble , driven either by the agn or by a nuclear starburst . on the other hand , most of the nuclear emission seems to be unresolved . with a beam size of 0.34@xmath100.49 , @xcite measured the unresolved flux to be 7mjy at 5ghz . at a resolution better than 0.1 , @xcite reported a 2.3ghz flux of 6mjy . based on this as well as non - detections at 1.7ghz and 8.4ghz , they estimated the core flux at 5ghz to be @xmath1666mjy . taking a flat spectral index , as indicated by archival data @xcite , one might expect the 5ghz core flux to be not much less than 6mjy , leaving room for only @xmath122mjy in extended emission in the central 0.5 . if we assume this difference can be attributed to star formation , it implies a supernova rate of @xmath167yr@xmath6 and hence @xmath168 . [ fig : stars ] shows that a ratio of this order is what one might expect for ages up to 200myr . however , given the uncertainty it does not impose a significant constraint . it is also difficult to quantify what fraction of the narrow br@xmath7 is associated with star formation . this is made clear in fig . [ fig : n2992_brg ] which shows that the morphology of the line ( centre left panel ) does not follow that of the stars ( far left ) . in addition , particularly the south - west side is associated with velocities that are bluer than the surrounding emission , indicative of motion towards us . the western edge also exhibits high velocity dispersion . taken together , these suggest that we may be seeing outflow from the apex of an ionisation cone with a relatively large opening angle . this interpretation would tend to support the hypothesis that the radio bubble has been driven by the agn . the stellar continuum appears to trace an inclined disk , the north west side of which is more obscured ( fig . [ fig : n2992_brg ] ) . however , the velocity dispersion is high , exceeding 150kms@xmath6 across the whole field ( fig . [ fig : n2992_vel ] ) . this is similar to the 160kms@xmath6 reported by @xcite from optical spectroscopy , and suggests that we are seeing bulge stars . to analyse the radial luminosity profile we have fitted it with both an @xmath55 law and exponential profile . the fits in fig . [ fig : n2992_rad ] were optimised at radii @xmath169  and then extrapolated inwards , convolved with the psf . whether one could claim that there is excess continuum in the nucleus depends on the profile fitted . the @xmath55 law provides a stronger constraint since it is more cuspy , and suggests there is no excess . although this evidence is inconclusive , fig . [ fig : n2992_vel ] suggests that there is some kinematic evidence favouring the existence of a distinct nuclear stellar population . this comes in the form of a small unresolved drop in dispersion at the centre , similar to those in ngc1097 and ngc1068 . while the evidence in ngc2992 is not compelling , the dispersion is consistent with there being an equivalent  but fainter  nuclear disk on a scale of less than our resolution of 50pc . in general it seems that the k - band light we are seeing is dominated by the bulge , and we are therefore unable to probe in detail the inner region where it seems that more recent star formation has probably occurred . thus , although the available data suggest there has likely been recent star formation in the nucleus of ngc2992 , the only strong constraint we can apply is that continuous star formation in the central arcsec over the last gyr can be ruled out since it would require @xmath17015 . we therefore omit ngc2992 from the discussion and analysis in sections  [ sec : prop ] and  [ sec : staragn ] .      in ngc1097 , the first evidence for recent star formation near the nucleus was in the form of a reduction in the stellar velocity dispersion . @xcite proposed this could be explained by the presence of a dynamically cold nuclear disk that had recently formed stars . direct observations of a spiral structure in the central few arcsec , from k - band imaging @xcite and [ nii ] streaming motions @xcite , have since confirmed this idea . however , some issues remain open , such as why there are three spiral arms rather than the usual two , and why gas along one of them appears to be outflowing .    our data , at a resolution of 0.25  measured from the h - band non - stellar continuum , also reveal the same spiral structure . indeed , we find that it is traced by the morphology of the co bandhead absorption as well as by the 2.12  h@xmath49 1 - 0s(1 ) line . interestingly , 1 - 0s(1 ) emission is stronger where the stellar features are weaker . this suggests that obscuration by gas and dust plays an important role . [ fig : n1097_prof ] shows that an @xmath55 law , typical of stellar bulges , with effective radius @xmath171  is a good fit to the stellar radial profile at @xmath172 . it therefore seems reasonable to argue that at these radii it is only the gas that lies in a disk . in this picture the spiral structure in the stellar continuum arises solely due to extinction of the stars behind the disk . extrapolating this fit , convolved with the psf , to the nucleus indicates that at @xmath173  there is at least 25% excess stellar continuum . there could be much more , given that it coincides with a change in the dominant kinematics .    for ngc1097 we parameterized the kinematics of the gas and stars quantitatively using kinemetry . based on the uniformity of the velocity field , we made the simplifying assumption that across the central 4  the gas lies in a single plane whose centre is coincident with the peak of the non - stellar emission . we were then able to derive the position angle and inclination of the disk ( see section  [ sec : obs ] ) . the 2d kinematics of the stars is traced via the co2 - 0 absorption bandhead , and that of the gas through the 1 - 0s(1 ) emission line . these independently yielded similar parameters : both gave a position angle of @xmath174 and their inclinations were 43@xmath175 and 32@xmath175 respectively . these are fully consistent with values found by other authors ( @xcite ) . the resulting rotation curves and velocity dispersions are shown in fig . [ fig : n1097_dispvel ] . the residuals , which can be seen in the velocity field of the gas but not the stars , and their relation to the spiral structure described above will be discussed elsewhere ( davies et al . in prep ) . the important result here is that at our spatial resolution , we find that the central stellar dispersion is @xmath176kms@xmath6 , less than the surrounding 150kms@xmath6 and also less than that in the seeing limited spectra of @xcite . in the same region we find that the rotation velocity of the gas starts to decrease rapidly , and its dispersion increases from @xmath177kms@xmath6 to @xmath178kms@xmath6 . [ fig : n1097_dispvel ] also shows that while the kinematics of the stars and gas are rather different at large ( @xmath179 ) radii , they are remarkably similar at radii @xmath180 . this certainly provides a strong indication that in the nuclear region the stars and gas are coupled , most likely in a ( perhaps thick ) disk ; and that the stars in this disk , which are bright and hence presumably young , give rise to the excess stellar continuum observed . evidence for a recent starburst has been found by @xcite through optical and uv spectra . they argued that a number of features they observed could only arise from an @xmath181m@xmath1 instantaneous starburst , which occurred a few myr ago and is reddened by @xmath182mag of extinction . using stars we have modeled this starburst as a @xmath181m@xmath1 burst beginning 8myr ago with an exponential decay timescale of 1myr . the age we have used is a little older to keep the br@xmath7 equivalent width low ; and at this age , the model predicts @xmath159 . as fig . [ fig : n1097_maps ] shows , the observed br@xmath7 is weak , although perhaps slightly resolved . corrected for the non - stellar continuum , we measure only @xmath183 . however , the bulge population may account for a significant fraction of the k - band stellar continuum . correcting also for this could increase @xmath57 to 25 , consistent with that of the model  assuming that the br@xmath7 is associated with the starburst rather than the agn . to within a factor of a few , the scale of the model starburst is also consistent with that measured : in the central 0.5  we measure a br@xmath7 flux of @xmath184wm@xmath2 , compared to that predicted by the model of @xmath185wm@xmath2 . given the uncertainties  factors of a few  both in the parameters of the starburst model and also in the corrections we have applied to the data , we consider this a good agreement . we can not constrain the starburst further due to its compactness . @xcite found that it was occurring in the central 0.2 , whereas our resolution is only 0.25 . the br@xmath7 emission is confined to the central 0.40.5 , although its size is hard to measure due to its weakness with respect to the stellar absorption features . in this region the k - band stellar luminosity is @xmath186l@xmath1 . to estimate the dynamical mass we use the mean kinematics of the stars and gas , i.e. v@xmath187kms@xmath6 ( corrected for inclination ) and @xmath188kms@xmath6 ( this is the central value , which is least biassed by bulge stars ) , yielding @xmath189m@xmath1 this is actually dominated by the black hole , which has a mass of @xmath190m@xmath1 @xcite . the difference between these implies a mass of gas and stars of @xmath191m@xmath1 , although with a large uncertainty . the associated mass - to - light ratio is @xmath192 . on its own , this implies that over the relatively large area that it encompasses , the maximum characteristic age for the star formation is a few hundred myr . if one speculates that star formation has been occurring sporadically for this timescale , then the starburst seen by @xcite is the most recent active episode .    in order to make a rough estimate of the supernova rate in the central region we make use of measurements reported by @xcite . they find an unresolved component ( size @xmath193 ) with 5ghz flux density @xmath194mjy , but at lower resolution there is a @xmath195mjy component of size 1 . as discussed in section  [ sec : diag ] we assume that the difference  albeit with only marginal significance  of @xmath196mjy is due to star formation in the central region , which implies a supernova rate of @xmath197yr@xmath6 and hence @xmath198 , a value consistent with rather more recent star formation . indeed , when compared to fig . [ fig : stars ] , this and the low @xmath57 imply a young age and short star formation timescale . for @xmath68myr the age is 6070myr ; for an instantaneous burst of star formation , the age would be @xmath80myr , broadly consistent with that of @xcite . thus , although our data do not uniquely constrain the age of the starburst in the nucleus of ngc1097 , they do indicate that recent star formation has occurred ; and they are consistent with a very young compact starburst similar to that derived from optical and uv data . evidence for a stellar core in ngc1068 with an intrinsic size scale of @xmath199pc was first presented by @xcite . based on kinematics measured in large ( 24 ) apertures , they assumed the core was virialized and estimated a mass - to - light ratio based on this assumption leading to an upper limit on the stellar age of 1600myr . making a reasonable correction for an assumed old component lead to a younger age of 500myr . stellar kinematics from optical integral field spectra @xcite show evidence for a drop in the stellar velocity dispersion in the central few arcsec to @xmath200kms@xmath6 , inside a region of higher 150200kms@xmath6 dispersion ( presumably the bulge ) . our near infrared adaptive optics data are able to fully resolve the inner region where @xmath60 drops , as shown in fig . [ fig : n1068_prof ] . as for ngc1097 , the velocity distribution of the stars was derived through kinemetry , again making use of the uniformity of the stellar velocity field to justify the simplifying assumption that the position angle and inclination do not change significantly in the central 4 . the derived inclination of @xmath201 and position angle of @xmath202 are quantitatively similar to those found by other authors in the central few to tens of arcseconds @xcite . the uniformity of the stellar kinematics is in contrast to molecular gas kinematics , as traced via the 1 - 0s(1 ) line , which are strongly perturbed and show several distinct structures superimposed . these are too complex to permit a comparably simple analysis and will be discussed , together with the residuals in the stellar kinematics in a future work ( mueller snchez et al . in prep ) . the crucial result relevant here is that at our h - band resolution of 0.10 we find that @xmath60 reduces from 130kms@xmath6 at 12  to only 70kms@xmath6 in the very centre . that there is in the same region an excess in the stellar continuum is demonstrated in fig . [ fig : n1068_prof_wide ] . here we show the radial profile of the stellar continuum from both sinfoni integral field spectra out to a radius of 2  and naco longslit spectra out to 5  ( 350pc ) . at radii 15 , corresponding roughly to the region of high stellar dispersion measured by @xcite , the profile is well matched by an @xmath55 law , as one might expect for a bulge . at radii @xmath203   the same radius at which we begin to see a discernable reduction in the stellar dispersion the stellar continuum increases by as much as a factor 2 above the inward extrapolation of the profile , indicating that there is extra emission . as for ngc1097 , the combined signature of dynamically cool kinematics and excess emission is strong evidence for a nuclear disk which has experienced recent star formation . we can make an estimate of the characteristic age of the star formation in the central arcsec based on the mass - to - light ratio in a similar way to @xcite . because the stars appear to lie in a disk , we estimate the dynamical mass as described in section  [ sec : diag ] from the stellar kinematics , using the rotation velocity and applying a correction for the dispersion . the stellar rotation curve is essentially flat at 0.10.5 , with @xmath204kms@xmath6 ( corrected for inclination ) . we also take @xmath205kms@xmath6 , which is the central value and hence least biassed by the high dispersion bulge stars . these lead to a mass of @xmath206m@xmath1 within @xmath207  ( 35pc ) , and a mean surface density of @xmath208m@xmath1pc@xmath2 . correcting for the non - stellar continuum , the h - band magnitude ( which the behaviour of @xmath60 indicates is dominated by the disk emission ) in the same region is 11.53mag . for @xmath26mag ( fig . [ fig : stars ] ) , we find @xmath209l@xmath1 and hence @xmath210m@xmath1/l@xmath1 . if no star formation is on - going , this implies a characteristic age of 200300myr fairly independent of the timescale ( for @xmath211myr , see fig . [ fig : stars ] ) on which stars were formed . we note that this is significantly younger than the age estimated by @xcite primarily because their mass was derived using a higher @xmath60 corresponding to the bulge stars . the assumption of no current star formation is clearly demonstrated by the br@xmath7 map in fig . [ fig : n1068_maps ] . away from the knots of br@xmath7 , which are associated with the coronal lines and the jet rather than possible star formation , the equivalent width is @xmath212 . this is significantly less than that for continuous star formation of any age . thus , while it seems likely that star formation has occurred in the last few hundred myr , it also seems an unavoidable conclusion that there is no current star formation .    to complete our set of diagnostics for ngc1068 , we consider also the radio continuum . this is clearly dominated by phenomena associated with the agn and jets , and our best estimate of the flux density away from these features is given by the lowest contour in maps such as figure  1 of @xcite . from this we estimate an upper limit to the 5ghz continuum associated with star formation of 128mjy within @xmath173 . however , converting to a supernova rate and comparing to the k - band stellar luminosity yields a limit that is not useful , being an order of magnitude above the largest expected values .      at near infrared wavelengths , the agn in ngc3783 is remarkably bright . integrated over the central 0.5  less than 4% of the k - band continuum is stellar . in addition , the broad brackett lines are very strong and dominate the h - band . both of these phenomena are immediately clear from the h- and k - band spectra in fig . [ fig : n3783_spec ] . however , it does mean that the spatial resolution can be measured easily from both the non - stellar continuum and the broad emission lines ( see section  [ sec : obs ] ) . we find the k - band psf to be symmetrical with a fwhm of 0.17 .    due to the ubiquitous brackett emission in the h - band we were unable to reliably trace the stellar absorption features and map out the stellar continuum . instead we have used the co2 - 0 bandhead at 2.3  even though the dilution at the nucleus itself is extreme . the azimuthally averaged radial profile is shown in fig . [ fig : n3783_rad ] together with the psf for reference . at radii from 0.21.6  ( the maximum we can measure ) the profile is well fit by an @xmath55 de vaucouleurs law with @xmath213  ( 120pc ) . as has been the case previously , at smaller radii we find an excess that here is perhaps marginally resolved . thus a substantial fraction of the near infrared stellar continuum in the central region is likely to originate in a population of stars distinct from the bulge . we were unable to measure the stellar kinematics due to the limited signal - to - noise . instead , we used the molecular gas kinematics to estimate the dynamical mass . as before , we used kinemetry to derive the position angle of @xmath214 and the inclination in the range 3539@xmath175 . this orientation is consistent with the larger ( 20 ) scale isophotes in the j - band 2mass image and implies that in ngc3783 there is no significant warp on scales of 50pc to 4kpc . a small inclination is also consistent with its classification as a seyfert  1 . adopting these values , the resulting rotation curve is shown in fig . [ fig : n3783_rot ] . at very small radii the rising rotation curve may be the result of beam smearing across the nucleus . at @xmath215 , the falling curve suggests that the rotation is dominated by the central ( @xmath216 ) mass , perhaps the supermassive black hole . we estimate the dynamical mass within a radius of 0.3  ( 60pc ) , corresponding to the point where the excess continuum begins and also where the rotation curve appears to be unaffected by beam smearing . taking @xmath217kms@xmath6 and @xmath218kms@xmath6 we derive a dynamical mass of m@xmath219m@xmath1 . the black hole mass of @xmath220m@xmath1 ( from reverberation mapping , @xcite ) is only 30% of this , and so can not be dominating the dynamics on this scale unless its mass is underestimated . with respect to this , we note that @xcite claim the statistical uncertainty in masses derived from reverberation mapping is about a factor 3 . alternatively , there may be a compact mass of gas and stars at @xmath221 . however , including @xmath53 in the mass estimate implicitly assumes that the dispersion arises from macroscopic motions . on the other hand , because we are observing only the hot h@xmath49 , it is possible that the dispersion is dominated by turbulence arising from shocks or uv heating of clouds that generate the 1 - 0s(1 ) emission issues that are discussed in more detail by hicks et al . ( in prep . ) . in this case we will have overestimated the dynamical mass . excluding @xmath53 from the mass estimation yields @xmath222m@xmath1 . we consider these two estimates as denoting the maximum range of possible masses . subtracting m@xmath223 then gives a mass of stars and gas in the range ( 27)@xmath224m@xmath1 , implying a mass surface density of 17006000m@xmath1pc@xmath2 and @xmath2252.1m@xmath1/l@xmath1 . based on these ratios alone , fig  [ fig : stars ] indicates that the characteristic age of the star formation may be as low as @xmath226myr , although it could also be an order of magnitude greater . without additional diagnostics we can not discriminate further . we are unable to use br@xmath7 as an additional constraint on the star formation history . its morphology and velocity field are similar to that of [ sivi ] , and rather different from the 1 - 0s(1 ) . it shows an extension to the north which appears to be outflowing at @xmath227kms@xmath6 ( fig  [ fig : n3783_maps ] )  perhaps tracing an ionisation cone . since the br@xmath7 resembles the [ sivi ] , it is reasonable to conclude that it too is associated with the agn rather than star formation . thus the equivalent width of br@xmath7 ( with respect to the stellar continuum ) of @xmath228  represents an upper limit to that associated with star formation . the radio continuum in the nucleus of ngc3783 has been measured with several beam sizes at 8.5ghz . for a beam of @xmath229 , @xcite found it was unresolved with a flux density of @xmath230mjy . with a smaller @xmath164  beam , @xcite measured a total flux density of 8.0mjy dominated by an unresolved component of @xmath231mjy . at smaller scales still of @xmath232  corresponding to 6pc , @xcite placed an upper limit on the 8.5ghz flux density of 7mjy . taken together , these results imply that there is some modest 8.5ghz radio continuum of 0.71mjy extended on scales of 0.31 . based on this we estimate a supernova rate as described in section  [ sec : diag ] of @xmath233yr@xmath6 , and hence a ratio @xmath234 . given that the unresolved radio continuum on the smallest scales is an upper limit , the extended component may be stronger and hence the true @xmath235 ratio may be greater than that estimated here . fig  [ fig : stars ] then puts a relatively strong limit of @xmath96myr on the maximum age of the star formation . this age is fully consistent with that above associated with our lower mass estimate . the value of @xmath236  above does not impose additional constraints , although we note that if the br@xmath7 flux associated with star formation is only a small fraction of the total then it would imply that the timescale over which the star formation was active is no longer than a few times @xmath80myr . therefore in the nucleus ( @xmath221 ) of ngc3783 we adopt 5070myr as the age of the star formation and @xmath237m@xmath1 as the dynamical mass excluding the central supermassive black hole . knapen j. , 2004 , in _ penetrating bars through masks of cosmic dust : the hubble tuning fork strikes a new note _ , eds block d. , puerari i. , freeman k. , groess r. , block e. ( dordrecht : kluwer academic publishers ) , assl , vol . 319 , p.189                                                                                                                mkn231 & h & 0.176 & may 02 & keck , nirc2 + ngc7469 & k & 0.085 & nov 02 & keck , nirspao + & k & 0.15 & jul 04 & vlt , sinfoni + circinus & k & 0.22 & jul 04 & vlt , sinfoni + ngc3227 & k & 0.085 & dec 04 & vlt , sinfoni + iras05189 - 2524 & h & 0.12 & dec 02 & vlt , naco + ngc2992 & k & 0.30 & mar 05 & vlt , sinfoni + ngc1097 & h & 0.245 & oct 05 & vlt , sinfoni + ngc1068 & h & 0.10 & oct 05 & vlt , sinfoni + & h & 0.13 & dec 02 & vlt , naco + ngc3783 & k & 0.17 & mar 05 & vlt , sinfoni +      mkn231 & ulirg , sy1 , qso & 170 & 12.5 & 7.2 & 1 & + ngc7469 & sy1 & 66 & 11.5 & 7.0 & 2 & + circinus & sy2 & 4 & 10.2 & 6.2 & 3 & + ngc3227 & sy1 & 17 & 10.2 & 7.3 & 4 & + iras05189 - 2524 & ulirg , sy1 & 170 & 12.1 & 7.5 & 1 & + ngc2992 & sy1 & 33 & 10.7 & 7.7 & 5 & + ngc1097 & liner , sy1 & 18 & 10.9 & 8.1 & 6 & + ngc1068 & sy2 & 14 & 11.5 & 6.9 & 7 & + ngc3783 & sy1 & 42 & 10.8 & 7.5 & 2 & +      mkn231 & 0.6 & 480 & 9.3 & 9.8 & 0.9 &  & 3.1 & 20 & 120250 & 2550 + ngc7469 & 0.4 & 128 & 8.5 & 8.7 & 1.0 & 11 & 1.6 & 3 & 110190 & 50100 + circinus & 0.4 & 8 & 6.2 & 7.5 & 17 & 30 & 23 & 1.5 & 80 & @xmath226 + ngc3227 & 0.4 & 32 & 7.8 & 8.0 & 3.7 & 4 & 1.9 & 2.2 & 40 & @xmath238 + iras05189 - 2524 & 0.55 & 450 & 9.3 &  &  & 4 &  & 5 & 50100 & 3070 + ngc2992 & 0.4 & 64 & 7.5 &  &  & @xmath16612 &  & 1 &  &  + ngc1097 & 0.25 & 22 & 6.7 & 8.2 & 1.3 & 1 & 4.5 & 1.4 & 8 & @xmath178 + ngc1068 & 0.5 & 35 & 7.6 & 8.1 & 3.4 & 4 & 3.0 & @xmath16620 & 200300 & 90170 + ngc3783 & 0.3 & 60 & 7.5 & 7.3 & 0.2 & @xmath16630 & 0.6 & 2 & 5070 & 3060 +
we analyse star formation in the nuclei of 9 seyfert galaxies at spatial resolutions down to 0.085 , corresponding to length scales of order 10pc in most objects . 
 our data were taken mostly with the near infrared adaptive optics integral field spectrograph sinfoni . 
 the stellar light profiles typically have size scales of a few tens of parsecs . in two cases 
 there is unambiguous kinematic evidence for stellar disks on these scales . in the nuclear regions there 
 appear to have been recent  but no longer active  starbursts in the last 10 - 300myr . the stellar luminosity is less than a few percent of the agn in the central 10pc , whereas on kiloparsec scales the luminosities are comparable . the surface stellar luminosity density follows a similar trend in all the objects , increasing steadily at smaller radii up to @xmath0l@xmath1kpc@xmath2 in the central few parsecs , where the mass surface density exceeds 10@xmath3m@xmath1pc@xmath2 . 
 the intense starbursts were probably eddington limited and hence inevitably short - lived , implying that the starbursts occur in multiple short bursts . 
 the data hint at a delay of 50100myr between the onset of star formation and subsequent fuelling of the black hole . 
 we discuss whether this may be a consequence of the role that stellar ejecta could play in fuelling the black hole . 
 while a significant mass is ejected by ob winds and supernovae , their high velocity means that very little of it can be accreted . on 
 the other hand winds from agb stars ultimately dominate the total mass loss , and they can also be accreted very efficiently because of their slow speeds .