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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 size distribution of void filaments in a ΛCDM cosmology
Park, Daeseong,Lee, Jounghun Blackwell Publishing Ltd 2009 MONTHLY NOTICES- ROYAL ASTRONOMICAL SOCIETY Vol.397 No.4
<P>ABSTRACT</P><P>The size distribution of minifilaments in voids has been derived from the Millennium Run halo catalogues at redshifts <I>z</I>= 0, 0.5, 1 and 2. It is assumed that the primordial tidal field originated the presence of filamentary substructures in voids and that the void filaments have evolved only little, keeping the initial memory of the primordial tidal field. Applying the filament-finding algorithm based on the minimal spanning tree (MST) technique to the Millennium voids, we identify the minifilaments running through voids and measure their sizes at each redshift. Then, we calculate the comoving number density of void filaments as a function of their sizes in the logarithmic interval and determine an analytic fitting function for it. It is found that the size distribution of void minifilaments in the logarithmic interval, d<I>N</I>/d log <I>S</I>, has an almost universal shape, insensitive to the redshift. In the short-size section, it is well approximated as a power law, d<I>N</I>/d log <I>S</I>≈<I>S</I>, while in the long-size section it decreases exponentially as d<I>N</I>/dlog <I>S</I>≈ exp(−<I>S</I><SUP>α</SUP>). We expect that the universal size distribution of void filaments may provide a useful cosmological probe without resorting to the rms density fluctuations.</P>
The bridge effect of void filaments
Park, Daeseong,Lee, Jounghun Blackwell Publishing Ltd 2009 MONTHLY NOTICES- ROYAL ASTRONOMICAL SOCIETY Vol.400 No.2
<P>ABSTRACT</P><P>Cosmic filaments play a role of bridges along which matter and gas accrete on to galaxies to trigger star formation and feed central black holes. Here, we explore the correlations between the intrinsic properties of void galaxies and the linearity <I>R</I><SUB>L</SUB> of void filaments (degree of filament's straightness). We focus on void regions since the bridge effect of filaments should be most conspicuous in the pristine underdense regions like voids. Analysing the Millennium-Run semi-analytic galaxy catalogue, we identify void filaments consisting of more than four galaxies (three edges) and calculate the means of central black hole mass, star formation rate, and stellar mass as a function of <I>R</I><SUB>L</SUB>. It is shown that the void galaxies constituting more straight filaments tend to have higher luminosity, more massive central black holes and higher star formation rate. Among the three properties, the central black hole mass is most strongly correlated with <I>R</I><SUB>L</SUB>. It is also shown that the dark haloes constituting straight filaments tend to have similar masses. Our results suggest that the fuel-supply for central black holes and star formation of void galaxies occurs most efficiently along straight void filaments whose potential wells are generated by similar-mass dark haloes.</P>
Park, Daeseong,Barth, Aaron J.,Woo, Jong-Hak,Malkan, Matthew A.,Treu, Tommaso,Bennert, Vardha N.,Assef, Roberto J.,Pancoast, Anna American Astronomical Society 2017 The Astrophysical journal Vol.839 No.2
<P>We provide an updated calibration of C IV lambda 1549 broad emission line-based single-epoch (SE) black hole (BH) mass estimators for active galactic nuclei (AGNs) using new data for six reverberation-mapped AGNs at redshift z = 0.005-0.028 with BH masses (bolometric luminosities) in the range 10(6.5)-10(7.5) M-circle dot (10(41.7)-10(43.8) erg s(-1)). New rest-frame UV-to-optical spectra covering 1150-5700 angstrom for the six AGNs were obtained with the Hubble Space Telescope (HST). Multicomponent spectral decompositions of the HST spectra were used to measure SE emission-line widths for the C IV, MgII, and H beta lines, as well as continuum luminosities in the spectral region around each line. We combine the new data with similar measurements for a previous archival sample of 25 AGNs to derive the most consistent and accurate calibrations of the C IV-based SE BH mass estimators against the H beta reverberation-based masses, using three different measures of broad-line width: full. width at half maximum (FWHM), line dispersion (sigma line), and mean absolute deviation (MAD). The newly expanded sample at redshift wz = 0.005-0.234 covers a dynamic range in BH mass (bolometric luminosity) of logM(BH)/M-circle dot = 6.5-9.1 (log L-bol/ erg s(-1) = 41.7-46.9), and we derive the new C IV-based mass estimators using a Bayesian linear regression analysis over this range. We generally recommend the use of sigma line or MAD rather than FWHM to obtain a less biased velocity measurement of the C IV emission line, because its narrow-line component contribution is difficult to decompose from the broad-line profile.</P>