Search Publications
Sizes and Temperature Profiles of Quasar Accretion Disks from Chromatic Microlensing
Schechter, Paul L.; Pooley, David; Blackburne, Jeffrey A. +1 more
Microlensing perturbations to the flux ratios of gravitationally lensed quasar images can vary with wavelength because of the chromatic dependence of the accretion disk's apparent size. Multiwavelength observations of microlensed quasars can thus constrain the temperature profiles of their accretion disks, a fundamental test of an important astrop…
Testing the Unification Model for Active Galactic Nuclei in the Infrared: Are the Obscuring Tori of Type 1 and 2 Seyferts Different?
Pérez García, A. M.; Díaz-Santos, T.; Packham, C. +7 more
We present new mid-infrared imaging data for three Type-1 Seyfert galaxies obtained with T-ReCS on the Gemini-South Telescope at subarcsecond resolution. Our aim is to enlarge the sample studied in a previous work to compare the properties of Type-1 and Type-2 Seyfert tori using clumpy torus models and a Bayesian approach to fit the infrared (IR) …
The Spin of the Supermassive Black Hole in NGC 3783
Nandra, K.; Iwasawa, K.; Fabian, A. C. +9 more
The Suzaku AGN Spin Survey is designed to determine the supermassive black hole spin in six nearby active galactic nuclei (AGNs) via deep Suzaku stares, thereby giving us our first glimpse of the local black hole spin distribution. Here, we present an analysis of the first target to be studied under the auspices of this Key Project, the Seyfert ga…
Pan-STARRS1 Discovery of Two Ultraluminous Supernovae at z ≈ 0.9
Price, P. A.; Berger, E.; Kirshner, R. P. +29 more
We present the discovery of two ultraluminous supernovae (SNe) at z ≈ 0.9 with the Pan-STARRS1 Medium Deep Survey. These SNe, PS1-10ky and PS1-10awh, are among the most luminous SNe ever discovered, comparable to the unusual transients SN 2005ap and SCP 06F6. Like SN 2005ap and SCP 06F6, they show characteristic high luminosities (M bol…
The Impact of Galaxy Interactions on Active Galactic Nucleus Activity in zCOSMOS
Finoguenov, A.; Jahnke, K.; Silverman, J. D. +52 more
Close encounters between galaxies are expected to be a viable mechanism, as predicted by numerical simulations, by which accretion onto supermassive black holes can be initiated. To test this scenario, we construct a sample of 562 galaxies (M * > 2.5 × 1010 M ⊙) in kinematic pairs over the redshift range 0.25 &l…
Quasar Accretion Disks are Strongly Inhomogeneous
Agol, Eric; Dexter, Jason
Active galactic nuclei have been observed to vary stochastically with 10%-20% rms amplitudes over a range of optical wavelengths where the emission arises in an accretion disk. Since the accretion disk is unlikely to vary coherently, local fluctuations may be significantly larger than the global rms variability. We investigate toy models of quasar…
Gas Clumping in the Outskirts of ΛCDM Clusters
Nagai, Daisuke; Lau, Erwin T.
Recent Suzaku X-ray observations revealed that the observed entropy profile of the intracluster medium (ICM) deviates significantly from the prediction of hydrodynamical simulations of galaxy clusters. In this work, we show that gas clumping introduces significant biases in X-ray measurements of the ICM profiles in the outskirts of galaxy clusters…
HST WFC3/IR Observations of Active Galactic Nucleus Host Galaxies at z ~ 2: Supermassive Black Holes Grow in Disk Galaxies
Schawinski, Kevin; Urry, C. Megan; Treister, Ezequiel +3 more
We present the rest-frame optical morphologies of active galactic nucleus (AGN) host galaxies at 1.5 < z < 3, using near-infrared imaging from the Hubble Space Telescope Wide Field Camera 3, the first such study of AGN host galaxies at these redshifts. The AGNs are X-ray-selected from the Chandra Deep Field South and have typical luminositie…
A Complete Sample of Ultraluminous X-ray Source Host Galaxies
Soria, Roberto; Tennant, Allyn F.; Swartz, Douglas A. +1 more
One hundred seven ultraluminous X-ray sources (ULXs) with 0.3-10.0 keV luminosities in excess of 1039 erg s-1 are identified in a complete sample of 127 nearby galaxies. The sample includes all galaxies within 14.5 Mpc above the completeness limits of both the Uppsala Galaxy Catalogue and the Infrared Astronomical Satellite s…
Exploring the Low-mass End of the M BH-σ* Relation with Active Galaxies
Ho, Luis C.; Barth, Aaron J.; Greene, Jenny E. +4 more
We present new measurements of stellar velocity dispersions, using spectra obtained with the Keck Echellette Spectrograph and Imager (ESI) and the Magellan Echellette (MagE), for 76 Seyfert 1 galaxies from the recent catalog of Greene & Ho. These objects were selected from the Sloan Digital Sky Survey (SDSS) to have estimated black hole (BH) m…