18485124
SINFONI adaptive optics integral field spectroscopy of the Circinus Galaxy
Aims. We investigate the star formation activity and the gas and stellar dynamics on scales of a few parsecs in the nucleus of the Circinus Galaxy. Methods. Using the adaptive optics near infrared integral field spectrometer SINFONI on the VLT, we have obtained observations of the Circinus galaxy on scales of a few parsecs and at a spectral resolution of 70 km s −1 FWHM. The physical properties of the nucleus are analyzed by means of line and velocity maps extracted from the SINFONI datacube. Starburst models are constrained using the Brγ flux, stellar continuum (as traced via the CO absorption bandheads longward of 2.3 µm), and radio continuum. Results. The similarity of the morphologies of the H2 1−0S (1) 2.12 µ ma nd Brγ 2.17 µm lines to the stellar continuum and also their kinematics, suggest a common origin in star formation. Within 8 pc of the AGN we find there has been a recent starburst in the last 100 Myr, which currently accounts for 1.4% of the galaxy’s bolometric luminosity. The similarity of the spatial scales over which the stars and gas exist indicates that this star formation is occuring within the torus; and comparison of the gas column density through the torus to the maximum possible optical depth to the stars implies the torus is a clumpy medium. The coronal lines show asymmetric profiles with a spatially compact narrow component and a spatially extended blue wing. These characteristics are consistent with some of the emission arising in clouds gravitationally bound to the AGN, and some outflowing in cloudlets which have been eroded away from the bound clouds.
55534407
The star-forming torus and stellar dynamical black hole mass in the Seyfert 1 nucleus of NGC 3227
We report R ~ 4300 VLT SINFONI adaptive optics integral field K-band spectroscopy of the nucleus of the Seyfert 1 galaxy NGC 3227 at a spatial resolution of 0085 (7 pc). We present the morphologies and kinematics of emission lines and absorption features and give the first derivation of a black hole mass in a Seyfert 1 nucleus from stellar dynamics (marginally resolving the black hole's sphere of influence). We show that the gas in the nucleus has a mean column density of order 1024 cm-2 and that it is geometrically thick, in agreement with the standard "molecular torus" scenario. We discuss possible heating processes responsible for maintaining the vertical height of the torus. We also resolve the nuclear stellar distribution and find that within a few parsecs of the AGN there has been an intense starburst, the most recent episode of which began ~40 Myr ago but has now ceased. The current luminosity of stars within 30 pc of the AGN, ~3 × 109 L☉, is comparable to that of the AGN. We argue that the star formation has been occurring in the obscuring material. Finally, we apply Schwarzschild orbit superposition models to our full two-dimensional data and derive the mass of the black hole, paying careful attention to the input parameters, which are often uncertain. Our models yield a 1 σ range for the black hole mass of MBH = 7 × 106-2 × 107 M☉.
118875154
LIINUS/SERPIL: a design study for interferometric imaging spectroscopy at the LBT
LIINUS/SERPIL is a design study to augment LBTs interferometric beam combiner camera LINC-NIRVANA with imaging spectroscopy. The FWHM of the interferometric main beam at 1.5 micron will be about 10 mas, offering unique imaging and spectroscopic capabilities well beyond the angular resolution of current 8-10m telescopes. At 10 mas angular scale, e.g., one resolution element at the distance of the Galactic Center corresponds to the average diameter of the Pluto orbit (79 AU), hence the size of the solar system. Taking advantage of the LBT interferometric beam with an equivalent maximum diameter of 23 m, LIINUS/SERPIL is an ideal precursor instrument for (imaging) spectrographs at extremely large full aperture telescopes. LIINUS/SERPIL will be built upon the LINC-NIRVANA hardware and LIINUS/SERPIL could potentially be developed on a rather short timescale. The study investigates several concepts for the optical as well as for the mechanical design. We present the scientific promises of such an instrument together with the current status of the design study.
119065042
Eddington-limited starbursts in the central 10 pc of AGN and the Torus in NGC1068
We present results from a survey of nearby AGN using the near infrared adaptive optics integral field spectrograph SINFONI. These data enable us to probe the distribution and kinematics of the gas and stars at spatial resolutions as small as 0.085arcsec. We find strong evidence for recent but short lived starbursts residing in very dense nuclear disks. On scales of less than 10pc these would have reached Eddington-limited luminosities when active, perhaps accounting for their short duration. In addition, for NGC1068 at a resolution of 6pc, we present direct observations of molecular gas close around the AGN which we identify with the obscuring torus.
119301588
The Impact of Nuclear Star Formation on Gas Inflow to AGN
Our adaptive optics observations of nearby AGN at spatial resolutions as small as 0.085arcsec show strong evidence for recent, but no longer active, nuclear star formation. We begin by describing observations that highlight two contrasting methods by which gas can flow into the central tens of parsecs. Gas accumulation in this region will inevitably lead to a starburst, and we discuss the evidence for such events. We then turn to the impact of stellar evolution on the further inflow of gas by combining a phenomenological approach with analytical modelling and hydrodynamic simulations. These complementary perspectives paint a picture in which all the processes are ultimately regulated by the mass accretion rate into the central hundred parsecs, and the ensuing starburst that occurs there. The resulting supernovae delay accretion by generating a starburst wind, which leaves behind a clumpy interstellar medium. This provides an ideal environment for slower stellar outflows to accrete inwards and form a dense turbulent disk on scales of a few parsecs. Such a scenario may resolve the discrepancy between the larger scale structure seen with adaptive optics and the small scale structure seen with VLTI.
15076787
MOLECULAR GAS STREAMERS FEEDING AND OBSCURING THE ACTIVE NUCLEUS OF NGC 1068
We report the first direct observations of neutral, molecular gas streaming in the nucleus of NGC 1068 on scales of <30 pc using SINFONI near-infrared integral field spectroscopy. At a resolution of 0075, the flux map of 2.12 μm 1-0 S(1) molecular hydrogen emission around the nucleus in the central arcsec reveals two prominent linear structures leading to the active galactic nucleus from the north and south. The kinematics of the gas in these features are dominated by noncircular motions and indicate that material streams toward the nucleus on highly elliptical or parabolic trajectories, whose orientations are compatible with that of the disk plane of the galaxy. We interpret the data as evidence for fueling of gas to the central region. The radial transport rate from ~30 pc to a few parsecs from the nucleus is ~15 M ☉ yr–1. One of the infalling clouds lies directly in front of the central engine. We interpret it as a tidally disrupted streamer that forms the optically thick outer part of an amorphous clumpy molecular/dusty structure which contributes to the nuclear obscuration.
122542628
Characterization of a high resolution triple Gas Electron Multiplier (GEM) detector
The development of a Gas Electron Multiplier (GEM) readout as an option for the TPC of the near detector of the T2K neutrino experiment is presented. The low track density and the wide range in polar angle of particles produced by neutrino interactions drive the initial choice of relatively large squared pads (8 mm) for the performance study. The physics requirements [T2K ND280 Conceptual Design Report, http://dpnc.unige.ch:8080/nu/Members/nabgrall/t2kge/t2kge_doc/cdr.pdf ] are a momentum resolution better than 10 % at 1 GeV/c and a 3 σ dE/dx separation between muons and electrons. Micro-pattern Gas Detectors (MPGDs) such as GEMs or Micromegas show several beneficial features compared to the traditional Multi-Wire Proportional Chambers. They have been tested in the HARP TPC environment at CERN. Preliminary results form the GEM tests are reported here.
118846693
Measuring the transition to homogeneity with photometric redshift surveys
We study the possibility of detecting the transition to homogeneity using photometric redshift catalogs. Our method is based on measuring the fractality of the projected galaxy distribution, using angular distances, and relies only on observable quantites. It thus provides a way to test the Cosmological Principle in a model-independent unbiased way. We have tested our method on dierent synthetic inhomogeneous catalogs, and shown that it is capable of discriminating some fractal models with relatively large fractal dimensions, in spite of the loss of information due to the radial projection. We have also studied the inuence of the redshift bin width, photometric redshift errors, bias, non-linear clustering, and surveyed area, on the angular homogeneity index H2( ) in a CDM cosmology. The level to which an upcoming galaxy survey will be able to constrain the transition to homogeneity will depend mainly on the total surveyed area and the compactness of the surveyed region. In particular, a Dark Energy Survey (DES)-like survey should be able to easily discriminate certain fractal models with fractal dimensions as large as D2 = 2:95. We believe that this method will have relevant applications for upcoming large photometric redshift surveys, such as DES or the Large Synoptic Survey Telescope (LSST).
109321144
HERA-B data acquisition system
Abstract The HERA-B Data Acquisition System implements a 50 kHz dead-timeless readout of 500 kB events requiring unprecedented speed of storing and data processing. The system is based on Digital Signal Processors (DSP) minimizing the number of components. A high bandwidth, low-latency DSP switching network provides full connectivity between the readout buffers and a PC farm which runs the higher level trigger. The design of the system and the achieved performance are described in this paper.
16638912
The forward-backward asymmetry for charm quarks at the Z pole
From 1.4 million hadronic Z decays collected by the ALEPH detector at LEP, an enriched sample of Z → cc events is extracted by requiring the presence of a high momentum D∗±. The charm quark forward-backward charge asymmetry at the Z pole is measured to be AFB0.c = (8.0 ± 2.4) % corresponding to an effective electroweak mixing angle of sin2θWeff = 0.2302 ± 0.0054.
111386784
Measurement of Lambda polarization from Z decays
The polarization of Λ baryons from Z decays is studied with the Aleph apparatus. Evidence of longitudinal polarization of s quarks from Z decay is observed for the first time. The measured longitudinal Λ polarization is PLΛ = −0.32 ± 0.07 for . This agrees with the prediction of −0.39 ± 0.08 from the standard model and the constituent quark model, where the error is due to uncertainties in the mechanism for Λ production. The observed Λ polarization is diluted with respect to the primary s quark polarization by Λ baryons without a primary s quark. Measurements of the Λ forward-backward asymmetry and of the correlation between back-to-back Λ pairs are used to check this dilution. In addition the transverse Λ polarization is measured. An indication of transverse polarization, more than two standard deviations away from zero, is found along the normal to the plane defined by the thrust axis and the Λ direction.