Search Publications
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…
The HETDEX Pilot Survey. II. The Evolution of the Lyα Escape Fraction from the Ultraviolet Slope and Luminosity Function of 1.9 < z < 3.8 LAEs
Finkelstein, Steven L.; Schneider, Donald P.; Roth, Martin M. +18 more
We study the escape of Lyα photons from Lyα emitting galaxies (LAEs) and the overall galaxy population using a sample of 99 LAEs at 1.9 < z < 3.8 detected through integral-field spectroscopy of blank fields by The Hobby Eberly Telescope Dark Energy Experiment Pilot Survey. For 89 LAEs with broadband counterparts we measure ultraviolet (UV) l…
The Distribution of Thermal Pressures in the Diffuse, Cold Neutral Medium of Our Galaxy. II. An Expanded Survey of Interstellar C I Fine-structure Excitations
Tripp, Todd M.; Jenkins, Edward B.
We analyzed absorption features arising from interstellar neutral carbon that appeared in the UV spectra of 89 stars recorded in the highest resolution echelle modes of the Space Telescope Imaging Spectrograph on board the Hubble Space Telescope so that we could determine the relative populations of collisionally excited fine-structure levels in t…
Herschel-ATLAS Galaxy Counts and High-redshift Luminosity Functions: The Formation of Massive Early-type Galaxies
Rodighiero, G.; Clements, D. L.; Danese, L. +35 more
Exploiting the Herschel Astrophysical Terahertz Large Area Survey Science Demonstration Phase survey data, we have determined the luminosity functions (LFs) at rest-frame wavelengths of 100 and 250 µm and at several redshifts z >~ 1, for bright submillimeter galaxies with star formation rates (SFRs) >~ 100 M ⊙ yr-1
A New Cepheid Distance to the Giant Spiral M101 Based on Image Subtraction of Hubble Space Telescope/Advanced Camera for Surveys Observations
Stanek, K. Z.; Shappee, Benjamin J.
We accurately determine a new Cepheid distance to M101 (NGC 5457) using archival Hubble Space Telescope (HST)/Advanced Camera for Surveys V and I time series photometry of two fields within the galaxy. We make a slight modification to the ISIS image subtraction package to obtain optimal differential light curves from HST data. We discovered 827 Ce…
Shocks and Cavities from Multiple Outbursts in the Galaxy Group NGC 5813: A Window to Active Galactic Nucleus Feedback
Simionescu, A.; Churazov, E.; Giacintucci, S. +10 more
We present results from new Chandra, GMRT, and SOAR observations of NGC 5813, the dominant central galaxy in a nearby galaxy group. The system shows three pairs of collinear cavities at 1 kpc, 8 kpc, and 20 kpc from the central source, from three distinct outbursts of the central active galactic nucleus (AGN), which occurred 3 × 106, 2 …