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THE LOW-LUMINOSITY END OF THE RADIUS-LUMINOSITY RELATIONSHIP FOR ACTIVE GALACTIC NUCLEI
Bentz, Misty C.,Denney, Kelly D.,Grier, Catherine J.,Barth, Aaron J.,Peterson, Bradley M.,Vestergaard, Marianne,Bennert, Vardha N.,Canalizo, Gabriela,De Rosa, Gisella,Filippenko, Alexei V.,Gates, Elin IOP Publishing 2013 The Astrophysical journal Vol.767 No.2
<P>We present an updated and revised analysis of the relationship between the H beta broad-line region (BLR) radius and the luminosity of the active galactic nucleus (AGN). Specifically, we have carried out two-dimensional surface brightness decompositions of the host galaxies of nine new AGNs imaged with the Hubble Space Telescope Wide Field Camera 3. The surface brightness decompositions allow us to create 'AGN-free' images of the galaxies, from which we measure the starlight contribution to the optical luminosity measured through the ground-based spectroscopic aperture. We also incorporate 20 new reverberation-mapping measurements of the H beta time lag, which is assumed to yield the average H beta BLR radius. The final sample includes 41 AGNs covering four orders of magnitude in luminosity. The additions and updates incorporated here primarily affect the low-luminosity end of the R-BLR-L relationship. The best fit to the relationship using a Bayesian analysis finds a slope of alpha = 0.533(-0.033)(+0.035), consistent with previous work and with simple photoionization arguments. Only two AGNs appear to be outliers from the relationship, but both of them have monitoring light curves that raise doubt regarding the accuracy of their reported time lags. The scatter around the relationship is found to be 0.19 +/- 0.02 dex, but would be decreased to 0.13 dex by the removal of these two suspect measurements. A large fraction of the remaining scatter in the relationship is likely due to the inaccurate distances to the AGN host galaxies. Our results help support the possibility that the R-BLR-L relationship could potentially be used to turn the BLRs of AGNs into standardizable candles. This would allow the cosmological expansion of the universe to be probed by a separate population of objects, and over a larger range of redshifts.</P>
THE LICK AGN MONITORING PROJECT: RECALIBRATING SINGLE-EPOCH VIRIAL BLACK HOLE MASS ESTIMATES
Park, Daeseong,Woo, Jong-Hak,Treu, Tommaso,Barth, Aaron J.,Bentz, Misty C.,Bennert, Vardha N.,Canalizo, Gabriela,Filippenko, Alexei V.,Gates, Elinor,Greene, Jenny E.,Malkan, Matthew A.,Walsh, Jonelle IOP Publishing 2012 The Astrophysical journal Vol.747 No.1
<P>We investigate the calibration and uncertainties of black hole (BH) mass estimates based on the single-epoch (SE) method, using homogeneous and high-quality multi-epoch spectra obtained by the Lick Active Galactic Nucleus (AGN) Monitoring Project for nine local Seyfert 1 galaxies with BH masses <10(8) M-circle dot. By decomposing the spectra into their AGNs and stellar components, we study the variability of the SE H beta line width (full width at half-maximum intensity, FWHMH beta or dispersion, sigma(H beta)) and of the AGN continuum luminosity at 5100 angstrom (L-5100). From the distribution of the 'virial products' (proportional to FWHMH beta 2 L-5100(0.5) or sigma(2)(H beta) L-5100(0.5)) measured from SE spectra, we estimate the uncertainty due to the combined variability as similar to 0.05 dex (12%). This is subdominant with respect to the total uncertainty in SE mass estimates, which is dominated by uncertainties in the size-luminosity relation and virial coefficient, and is estimated to be similar to 0.46 dex (factor of similar to 3). By comparing the H beta line profile of the SE, mean, and root-mean-square (rms) spectra, we find that the H beta line is broader in the mean (and SE) spectra than in the rms spectra by similar to 0.1 dex (25%) for our sample with FWHMH beta < 3000 km s(-1). This result is at variance with larger mass BHs where the difference is typically found to be much less than 0.1 dex. To correct for this systematic difference of the H beta line profile, we introduce a line-width dependent virial factor, resulting in a recalibration of SE BH mass estimators for low-mass AGNs.</P>
THE MASS OF THE BLACK HOLE IN Arp 151 FROM BAYESIAN MODELING OF REVERBERATION MAPPING DATA
Brewer, Brendon J.,Treu, Tommaso,Pancoast, Anna,Barth, Aaron J.,Bennert, Vardha N.,Bentz, Misty C.,Filippenko, Alexei V.,Greene, Jenny E.,Malkan, Matthew A.,Woo, Jong-Hak IOP Publishing 2011 ASTROPHYSICAL JOURNAL LETTERS - Vol.733 No.2
<P>Supermassive black holes are believed to be ubiquitous at the centers of galaxies. Measuring their masses is extremely challenging yet essential for understanding their role in the formation and evolution of cosmic structure. We present a direct measurement of the mass of a black hole in an active galactic nucleus (Arp 151) based on the motion of the gas responsible for the broad emission lines. By analyzing and modeling spectroscopic and photometric time series, we find that the gas is well described by a disk or torus with an average radius of 3.99 +/- 1.25 light days and an opening angle of 68.9(-17.2)(+21.4) deg, viewed at an inclination angle of 67.8 +/- 7.8 deg (that is, closer to face-on than edge-on). The black hole mass is inferred to be 10(6.51 +/- 0.28) M-circle dot. The method is fully general and can be used to determine the masses of black holes at arbitrary distances, enabling studies of their evolution over cosmic time.</P>