14133011
The Unified Model of Active Galactic Nuclei. I. Non-Hidden Broad-Line Region Seyfert 2 and Narrow-Line Seyfert 1 Galaxies
The unified model of Seyfert galaxies suggests that there are hidden broad-line regions (HBLRs) in Seyfert 2 galaxies (S2s). However, there is increasing evidence for the appearance of a subclass of S2s lacking HBLRs (non-HBLR S2s). An interesting issue arises as to the relations of non-HBLR S2s with other types of Seyfert galaxies and whether or not they can be included in the unified model. We assemble two subsamples consisting of 42 non-HBLR S2s and 44 narrow-line Seyfert 1 galaxies (NLS1s) with redshift z ? 0.05 from published literatures to explore this issue. We compare black hole masses in the galactic centers, accretion rates, and infrared color ratio (f60 ?m/f25 ?m) as a potential indicator of the dusty torus orientation, [O III] ?5007, radio, and far-infrared luminosities. We find that non-HBLR S2s and NLS1s have (1) similar distributions of black hole masses [ ? 107 M?] and Eddington ratios (LBol/LEdd ~ 1); (2) significantly different distributions of f60 ?m/f25 ?m ratios; and (3) similar distributions of bulge magnitudes and luminosities of [O III], radio, and far-infrared emission. The similarities and differences can be understood naturally if they are intrinsically the same, but non-HBLR S2s are viewed at larger angles of the observer's sight than NLS1s. We thus suggest that non-HBLR S2s only have narrower broad-line regions and that they are the counterparts of NLS1s viewed at high inclination angles. The absence of the polarized emission line in non-HBLR S2s is caused by the less massive black holes and high accretion rate similar to NLS1s. The implications of the unification scheme of non-HBLR S2s and NLS1s are discussed.
119102309
Possible hard X-ray shortages in bursts from KS 1731-260 and 4U 1705-44
Aims. A hard X-ray shortage, implying the cooling of the corona, was observed during bursts of IGR J17473-272, 4U 1636-536, Aql X-1, and GS 1826-238. Apart from these four sources, we investigate here an atoll sample, in which the number of bursts for each source is larger than 5, to explore the possible additional hard X-ray shortage during Rossi X-ray timing explorer (RXTE) era. Methods. According to the source catalog that shows type-I bursts, we analyzed all the available pointing observations of these sources carried out by the RXTE proportional counter array. We grouped and combined the bursts according to their outburst states and searched for the possible hard X-ray shortage while bursting. Results. We found that the island states of KS 1731-260 and 4U 1705-44 show a hard X-ray shortage at significant levels of 4.5 and 4.7σ and a systematic time lag of 0.9 ± 2.1 s and 2.5 ± 2.0 s with respect to the soft X-rays, respectively. While in their banana branches and other sources, we did not find any consistent shortage.
15715110
Suppressed star formation in circumnuclear regions in seyfert galaxies
Feedback from black hole activity is widely believed to play a key role in regulating star formation and black hole growth. A long-standing issue is the relation between star formation and the fueling of the supermassive black holes in active galactic nuclei (AGNs). We compile a sample of 57 Seyfert galaxies to tackle this issue. We estimate the surface densities of gas and star formation rates in circumnuclear regions (CNRs). Comparing them with the well-known Kennicutt-Schmidt (K-S) law, we find that the star formation rates (SFRs) in the CNRs of most Seyfert galaxies are suppressed in this sample. Feedback is suggested to explain the suppressed SFRs.
119263279
The 2008 outburst of IGR J17473–2721: evidence for a disk corona?
Context. The 2008 outburst of the atoll source IGR J17473–2721 was observed by INTEGRAL, RXTE and Swift. Tens of type-I X-ray bursts were found in this outburst. Aims. Joint observations by INTEGRAL, RXTE, and Swift provide sufficient data to look into the behavior of IGR J17473–2721 at the rising part of the 2008 outburst. The relation between the duration of the bursts and the accretion rate and the nature of the corona producing the observed power-law component can therefore be studied in detail. Methods. We analyze observational data of IGR J17473–2721, focusing on the spectral evolution during the state transition from quiescent to low hard state (LHS), and on the flux dependence of the type-I X-ray bursts along the outburst. Results. We find that the joint INTEGRAL, RXTE and Swift energy spectrum can be well fitted with a model composed of a blackbody and a cutoff power-law, with a cutoff energy decreasing from ∼150 keV to ∼40 keV as the source leaves the quiescent state toward the low hard state. This fits into a scenario in which the corona is cooled by the soft X-rays along the outburst evolution, as observed in several other atoll sources. Fifty-seven type-I bursts were reported in the 2008 outburst of IGR J17473–2721. By using the flux measured in the 1.5–30 keV band, we find that the linear relationship between the burst duration and the flux still holds for those bursts that occur at the decaying part of the low hard state, but with a different slope than the overall one that was estimated with the bursts happening in the whole extent of, and for the rest of the low hard state. The significance of such a dichotomy in the type-I X-ray bursts is ∼3σ under an F-test. Similar results are hinted at as well with the broader energy-band that was adopted recently. This dichotomy may be understood in a scenario where part of the accreting material forms a corona on the way of falling onto the surface of the neutron star during the decaying part of the low hard state.Based on the accretion rates of the preceding LHS, estimated from type-I X-ray bursts and from persistent emission, at least for IGR J17473-2721, most of the accretion material may fall on the neutron star (NS) surface in the LHS. Considering the burst behavior in the context of the outburst indicates a corona formed on top of the disk rather than on the NS surface.
14071619
The Mass Distribution of Black Holes in BL Lacertae Objects
In this {\it Letter}, we make an attempt to estimate the masses of black holes and their distributions in BL Lac objects. We find there is a bimodal population of black hole masses in BL Lacs: the first has a lower-mass peak centred at $\sim 7.0 \times 10^6\sunm$ composed of high frequency-peaked BL Lacs (HBLs) and the second is a higher-mass ($>10^9\sunm$) population composed of low frequency-peaked BL Lacs (LBLs). The low mass family of black holes in HBLs does not satisfy the Magorrian et al. relation whereas the high mass family in LBLs does this relation and is in agreement with Laor's limit. The origination of the bimodal distribution of black hole mass remains open.
119247847
THE HARD X-RAY BEHAVIOR OF AQL X-1 DURING TYPE-I BURSTS
We report the discovery of an anti-correlation between the soft and hard X-ray light curves of the X-ray binary Aql X-1 when bursting. This behavior may indicate that the corona is cooled by the soft X-ray shower fed by the type-I X-ray bursts, and that this process happens within a few seconds. Stacking the Aql X-1 light curves of type-I bursts, we find a shortage in the 40-50 keV band, delayed by 4.5 ± 1.4 s with respect to the soft X-rays. The photospheric radius expansion bursts are different in that neither a shortage nor an excess shows up in the hard X-ray light curve.
20853925
Development of Longitudinal Coupling Impedance Measurement Platform for BEPCII
A coaxial line impedance measurement platform is developed for BEPCII under the collaboration between Tsinghua University and IHEP. A pair of gradual change impedance matching section is designed and fabricated by numerical control milling machine. The special designed RF connector is applied to strengthen the inner conductor. The algorithm of TRL calibration is applied in the system to avoid the usage of a reference pipe for each device under test. The measurement is accomplished by a VNA under the control of the software written in LabView.
118840032
Weighing Super-Massive Black Holes with Narrow Fe K$\alpha$ Line
It has been suggested that the narrow cores of the Fe Kα emission lines in Active Galactic Nuclei (AGNs) are likely produced in the torus, the inner radius of which can be measured by observing the lag time between the V and K band flux variations. In this paper, we compare the virial products of the infrared time lags, and the narrow Fe Kα widths for 10 type 1 AGNs, with the black hole masses from other techniques. We found the narrow Fe Kα line width is in average 2.6 −0.4 times broader than expected, assuming an isotropic velocity distribution of the torus at the distance measured by the infrared lags. We propose the thick disk model of the torus may explain the observed larger line width. Another possibility is the contamination by emission from the broad line region or the outer accretion disk. Alternatively, the narrow iron line might originate from the inner most part of the obscuring torus within the sublimation radius, while the infrared emission may be from the outer cooler part. We note the correlations between the black hole masses based on this new technique and those based on other known techniques are statistically insignificant. We argue that this could be attributed to the small sample size and the very large uncertainties in the measurements of iron K line widths. The next generation of X-ray observatories could help verify the origin of the narrow iron Kα line and the reliability of this new technique. Subject headings: black hole physics – galaxies: active – galaxies: nuclei – galaxies: Seyfert – X-rays: galaxies – infrared: galaxies
9792067
A Comprehensive Study of 2000 Narrow Line Seyfert 1 Galaxies from the Sloan Digital Sky Survey. I. The Sample
This is the first paper in a series dedicated to the study of the emission-line and continuum properties of narrow line Seyfert 1 galaxies (NLS1s). We carried out a systematic search for NLS1s from objects assigned as "QSOs'' or "galaxies'' in the spectroscopic sample of the Sloan Digital Sky Survey Data Release 3 (SDSS DR3) by a careful modeling of their emission lines and continua. The result is a uniform sample comprising similar to 2000 NLS1s. This sample dramatically increases the number of known NLS1s by a factor of similar to 10 over previous compilations. This paper presents the parameters of the prominent emission lines and continua, which were measured accurately with typical uncertainties < 10%. Taking advantage of such an unprecedented large and uniform sample with accurately measured spectral parameters, we carried out various statistical analyses, some of which were only possible for the first time. The main results found are as follows. (1) Within the overall Seyfert 1 population, the incidence of NLS1s is strongly dependent on the optical, X-ray, and radio luminosities as well as the radio loudness. The fraction of NLS1s peaks around SDSS g-band absolute magnitude M-g similar to -22 mag in the optical and similar to 10(43.2) ergs s(-1) in the soft X-ray band, and decreases quickly as the radio loudness increases. (2) On average the relative Fe II emission, R-4570 = Fe II lambda lambda 4434-4684/H beta, in NLS1s is about twice that in normal active galactic nuclei (AGNs) and is anticorrelated with the broad component width of the Balmer emission lines. (3) The well-known anticorrelation between the width of broad low-ionization lines and the soft X-ray spectral slope for broad line AGNs extends down to FWHM similar to 1000 km s(-1) in NLS1s, but the trend appears to reverse at still smaller line widths. (4) The equivalent width of H beta and Fe II emission lines are strongly correlated with the H beta and continuum luminosities. (5) We do not find any difference between NLS1s and normal AGNs in regard to the narrow line region. (6) We have examined the black hole mass versus stellar velocity dispersion (M-BH-sigma(*)) relation for a subsample of 308 NLS1s for which sigma(*) could be measured directly from fitting the starlight in the SDSS spectra with our stellar spectral templates. A significant correlation between M-BH and sigma(*) is found, but with the bulk of black hole masses falling below the values expected from the M-BH-sigma(*) relation for normal galaxies and normal AGNs. This result indicates that NLS1s are underage AGNs, where the growth of the SMBH lags behind the formation of the galactic bulge. (7) We also find that the FWHM of [N II] line is well correlated with sigma(*) in 206 NLS1s, for which both parameters could be derived with reasonable accuracy. The [N II] width can predict the stellar velocity dispersion to an accuracy of similar to 30%. A similar M-BH-sigma(*) relation could be found for a larger sample of 613 NLS1s on making use of the more reliable measurements of FWHM[N II].
207917728
AN FPGA-BASED TUNE MEASUREMENT SYSTEM FOR THE APS BOOSTER SYNCHROTRON
The Advanced Photon Source (APS) injection booster is a 7-GeV electron synchrotron with a ramping time of 226 ms and a repetition rate of 2 Hz. A real-time tune measurement system is needed in order to monitor and correct tune drift during the 226-ms energy ramp. Such a drift occurs during user beam operations, especially during continuous top-up operations, and results in shotto-shot efficiency fluctuations. We designed and developed an FPGA-based system that pings the beam at variable intervals and measures tunes. An operational system has been built and commissioned. It has achieved a time resolution of better than 2 ms and a tune resolution of better than 0.001. This report describes the system design and main parameters, and results from our preliminary commissioning. We also briefly discuss the application of such a system in ramping correction and ring diagnostics.
10487035
Suppressed decays of D(s)(+) mesons to two pseudoscalar mesons.
Using data collected near the D{s}{*+}D{s}{-} peak production energy E_{cm}=4170 MeV by the CLEO-c detector, we study the decays of D{s}{+} mesons to two pseudoscalar mesons. We report on searches for the singly Cabibbo-suppressed D{s}{+} decay modes K{+}eta, K{+}eta', pi{+}K{S}{0}, K{+}pi{0}, and the isospin-forbidden decay mode D{s}{+}-->pi{+}pi{0}. We normalize with respect to the Cabibbo-favored D{s}{+} modes pi{+}eta, pi{+}eta', and K{+}K{S}{0}, and obtain ratios of branching fractions: B(D{s}{+}-->K{+}eta)/B(D{s}{+}-->pi{+}eta)=(8.9+/-1.5+/-0.4)%, B(D{s}{+}-->K{+}eta')/B(D{s}{+}-->pi{+}eta')=(4.2+/-1.3+/-0.3)%, B(D{s}{+}-->pi{+}K{S}{0})/B(D{s}{+}-->K{+}K{S}{0})=(8.2+/-0.9+/-0.2)%, B(D{s}{+}-->K{+}pi{0})/B(D{s}{+}-->K{+}K{S}{0})=(5.5+/-1.3+/-0.7)%, and B(D{s}{+}-->pi{+}pi{0})/B(D{s}{+}-->K{+}K{S}{0})<4.1% at 90% C.L., where the uncertainties are statistical and systematic, respectively.