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BROAD H<i>β</i>EMISSION-LINE VARIABILITY IN A SAMPLE OF 102 LOCAL ACTIVE GALAXIES
Runco, Jordan N.,Cosens, Maren,Bennert, Vardha N.,Scott, Bryan,Komossa, S.,Malkan, Matthew A.,Lazarova, Mariana S.,Auger, Matthew W.,Treu, Tommaso,Park, Daeseong American Astronomical Society 2016 The Astrophysical journal Vol.821 No.1
<P>A sample of 102 local (0.02 <= z <= 0.1) Seyfert galaxies with black hole masses M-BH > 10(7)M(circle dot) was selected from the Sloan Digital Sky Survey (SDSS) and observed using the Keck 10 m telescope to study the scaling relations between M-BH and host galaxy properties. We study profile changes of the broad H beta emission line within the three to nine year time frame between the two sets of spectra. The variability of the broad H beta emission line is of particular interest, not only because it is used to estimate M-BH, but also because its strength and width are used to classify Seyfert galaxies into different types. At least some form of broad-line variability (in either width or flux) is observed in the majority (similar to 66%) of the objects, resulting in a Seyfert-type change for similar to 38% of the objects, likely driven by variable accretion and/or obscuration. The broad H beta line virtually disappears in 3/102 (similar to 3%) extreme cases. We discuss potential causes for these changing look active galactic nuclei. While similar dramatic transitions have previously been reported in the literature, either on a case-by-case basis or in larger samples focusing on quasars at higher redshifts, our study provides statistical information on the frequency of H beta line variability in a sample of low-redshift Seyfert galaxies.</P>
Bennert, Vardha N.,Treu, Tommaso,Auger, Matthew W.,Cosens, Maren,Park, Daeseong,Rosen, Rebecca,Harris, Chelsea E.,Malkan, Matthew A.,Woo, Jong-Hak IOP Publishing 2015 The Astrophysical journal Vol.809 No.1
<P>We create a baseline of the black hole (BH) mass (M-BH)-stellar-velocity dispersion (sigma) relation for active galaxies, using a sample of 66 local (0.02 < z < 0.09) Seyfert-1 galaxies, selected from the Sloan Digital Sky Survey (SDSS). Analysis of SDSS images yields AGN luminosities free of host-galaxy contamination, and morphological classification. 51/66 galaxies have spiral morphology. Out of these, 28 bulges have Sersic index n < 2 and are considered candidate pseudo-bulges, with eight being definite pseudo-bulges based on multiple classification criteria met. Only 4/66 galaxies show signs of interaction/merging. High signal-to-noise ratio Keck spectra provide the width of the broad H beta emission line free of Fe II emission and stellar absorption. AGN luminosity and H beta line widths are used to estimate M-BH. The Keck-based spatially resolved kinematics is used to determine stellar-velocity dispersion within the spheroid effective radius (sigma(spat,reff)). We find that sigma can vary on average by up to 40% across definitions commonly used in the literature, emphasizing the importance of using self-consistent definitions in comparisons and evolutionary studies. The M-BH-sigma relation for our Seyfert-1 galaxy sample has the same intercept and scatter as that of reverberation-mapped AGNs as well as that of quiescent galaxies, consistent with the hypothesis that our single epoch M-BH estimator and sample selection function do not introduce significant biases. Barred galaxies, merging galaxies, and those hosting pseudo-bulges do not represent outliers in the M-BH-sigma relation. This is in contrast with previous work, although no firm conclusion can be drawn on this matter due to the small sample size and limited resolution of the SDSS images.</P>
THE LICK AGN MONITORING PROJECT 2011: SPECTROSCOPIC CAMPAIGN AND EMISSION-LINE LIGHT CURVES
Barth, Aaron J.,Bennert, Vardha N.,Canalizo, Gabriela,Filippenko, Alexei V.,Gates, Elinor L.,Greene, Jenny E.,Li, Weidong,Malkan, Matthew A.,Pancoast, Anna,Sand, David J.,Stern, Daniel,Treu, Tommaso,W IOP Publishing 2015 The Astrophysical journal Supplement series Vol.217 No.2
<P>In the Spring of 2011 we carried out a 2.5 month reverberation mapping campaign using the 3 m Shane telescope at Lick Observatory, monitoring 15 low-redshift Seyfert 1 galaxies. This paper describes the observations, reductions and measurements, and data products from the spectroscopic campaign. The reduced spectra were fitted with a multicomponent model in order to isolate the contributions of various continuum and emission-line components. We present light curves of broad emission lines and the active galactic nucleus (AGN) continuum, and measurements of the broad H beta line widths in mean and rms spectra. For the most highly variable AGNs we also measured broad Ha line widths and velocity centroids from the nightly spectra. In four AGNs exhibiting the highest variability amplitudes, we detect anticorrelations between broad H beta width and luminosity, demonstrating that the broad-line region 'breathes' on short timescales of days to weeks in response to continuum variations. We also find that broad Ha velocity centroids can undergo substantial changes in response to continuum variations; in NGC 4593, the broad H beta velocity shifted by similar to 250 km s(-1) over a 1 month period. This reverberation-induced velocity shift effect is likely to contribute a significant source of confusion noise to binary black hole searches that use multi-epoch quasar spectroscopy to detect binary orbital motion. We also present results from simulations that examine biases that can occur in measurement of broad-line widths from rms spectra due to the contributions of continuum variations and photon-counting noise.</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>
Ko, Jongwan,Im, Myungshin,Lee, Hyung Mok,Lee, Myung Gyoon,Kim, Seong Jin,Shim, Hyunjin,Jeon, Yiseul,Hwang, Ho Seong,Willmer, Christopher N. A.,Malkan, Matthew A.,Papovich, Casey,Weiner, Benjamin J.,Ma IOP Publishing 2012 The Astrophysical journal Vol.745 No.2
<P>We present the mid-infrared (MIR) properties of galaxies within a supercluster in the north ecliptic pole region at z similar to 0.087 observed with the AKARI satellite. We use data from the AKARI NEP-Wide (5.4 deg(2)) IR survey and the CLusters of galaxies EVoLution studies (CLEVL) mission program. We show that near-IR (3 mu m)-mid-IR (11 mu m) color can be used as an indicator of the specific star formation rate and the presence of intermediate-age stellar populations. From the MIR observations, we find that red-sequence galaxies consist not only of passively evolving red early-type galaxies, but also of (1) 'weak-SFGs' (disk-dominated star-forming galaxies that have star formation rates lower by similar to 4 x than blue-cloud galaxies) and (2) 'intermediate-MXGs' (bulge-dominated galaxies showing stronger MIR dust emission than normal red early-type galaxies). These two populations can be a set of transition galaxies from blue, star-forming, late-type galaxies evolving into red, quiescent, early-type ones. We find that the weak-SFGs are predominant at intermediate masses (10(10) M-circle dot < M-* < 10(10.5) M-circle dot) and are typically found in local densities similar to the outskirts of galaxy clusters. As much as 40% of the supercluster member galaxies in this mass range can be classified as weak-SFGs, but their proportion decreases to <10% at larger masses (M-* > 10(10.5) M-circle dot) at any galaxy density. The fraction of the intermediate-MXG among red-sequence galaxies at 10(10) M-circle dot < M-* < 10(11) M-circle dot also decreases as the density and mass increase. In particular, similar to 42% of the red-sequence galaxies with early-type morphologies are classified as intermediate-MXGs at intermediate densities. These results suggest that the star formation activity is strongly dependent on the stellar mass, but that the morphological transformation is mainly controlled by the environment.</P>
Calibration and Limitations of the Mg ii Line-based Black Hole Masses
Woo, Jong-Hak,Le, Huynh Anh N.,Karouzos, Marios,Park, Dawoo,Park, Daeseong,Malkan, Matthew A.,Treu, Tommaso,Bennert, Vardha N. American Astronomical Society 2018 The Astrophysical journal Vol.859 No.2
<P>We present single-epoch black hole mass (M-BH) calibrations based on the rest-frame ultraviolet (UV) and optical measurements of Mg II 2798 angstrom and H beta 4861 angstrom lines and the active galactic nucleus (AGN) continuum, using a sample of 52 moderate-luminosity AGNs at z similar to 0.4 and z similar to 0.6 with high-quality Keck spectra. We combine this sample with a large number of luminous AGNs from the Sloan Digital Sky Survey to increase the dynamic range for a better comparison of UV and optical velocity and luminosity measurements. With respect to the reference M-BH based on the line dispersion of H beta and continuum luminosity at 5100 angstrom, we calibrate the UV and optical mass estimators by determining the best-fit values of the coefficients in the mass equation. By investigating whether the UV estimators show a systematic trend with Eddington ratio, FWHM of H beta, Fe II strength, or UV/optical slope, we find no significant bias except for the slope. By fitting the systematic difference of Mg II-based and H beta-based masses with the L-3000/L-5100 ratio, we provide a correction term as a function of the spectral index as Delta C = 0.24 (1 + alpha(lambda)) + 0.17, which can be added to the Mg II-based mass estimators if the spectral slope can be well determined. The derived UV mass estimators typically show >similar to 0.2 dex intrinsic scatter with respect to the H beta-based MBH, suggesting that the UV-based mass has an additional uncertainty of similar to 0.2 dex, even if high-quality rest-frame UV spectra are available.</P>
THE LICK AGN MONITORING PROJECT 2011: DYNAMICAL MODELING OF THE BROAD-LINE REGION IN Mrk 50
Pancoast, Anna,Brewer, Brendon J.,Treu, Tommaso,Barth, Aaron J.,Bennert, Vardha N.,Canalizo, Gabriela,Filippenko, Alexei V.,Gates, Elinor L.,Greene, Jenny E.,Li, Weidong,Malkan, Matthew A.,Sand, David IOP Publishing 2012 The Astrophysical journal Vol.754 No.1
<P>We present dynamical modeling of the broad- line region (BLR) in the Seyfert 1 galaxy Mrk 50 using reverberation mapping data taken as part of the Lick AGN Monitoring Project (LAMP) 2011. We model the reverberation mapping data directly, constraining the geometry and kinematics of the BLR, as well as deriving a black hole mass estimate that does not depend on a normalizing factor or virial coefficient. We find that the geometry of the BLR in Mrk 50 is a nearly face-on thick disk, with a mean radius of 9.6(-0.9)(+1.2) light days, a width of the BLR of 6.9(-1.1)(+1.2) light days, and a disk opening angle of 25 +/- 10 deg above the plane. We also constrain the inclination angle to be 9(-5)(+7) deg, close to face-on. Finally, the black hole mass of Mrk 50 is inferred to be log(10)(M-BH/M-circle dot) = 7.57(-0.27)(+0.44). By comparison to the virial black hole mass estimate from traditional reverberation mapping analysis, we find the normalizing constant (virial coefficient) to be log(10) f = 0.78(-0.27)(+0.44), consistent with the commonly adopted mean value of 0.74 based on aligning the M-BH-sigma* relation for active galactic nuclei and quiescent galaxies. While our dynamical model includes the possibility of a net inflow or outflow in the BLR, we cannot distinguish between these two scenarios.</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>