Search Publications
Understanding Dual Active Galactic Nucleus Activation in the nearby Universe
Koss, Michael; Veilleux, Sylvain; Mushotzky, Richard +3 more
We study the fraction of dual active galactic nuclei (AGNs) in a sample of 167 nearby (z < 0.05), moderate-luminosity, ultra-hard X-ray-selected AGNs from the all-sky Swift Burst Alert Telescope (BAT) survey. Combining new Chandra and Gemini observations together with optical and X-ray observations, we find that the dual AGN frequency at scales…
The Structure and Emission Model of the Relativistic Jet in the Quasar 3C 279 Inferred from Radio to High-energy γ-Ray Observations in 2008-2010
Sakamoto, T.; Greiner, J.; Lähteenmäki, A. +90 more
We present time-resolved broadband observations of the quasar 3C 279 obtained from multi-wavelength campaigns conducted during the first two years of the Fermi Gamma-ray Space Telescope mission. While investigating the previously reported γ-ray/optical flare accompanied by a change in optical polarization, we found that the optical emission appear…
Chandra/HETGS Observations of the Brightest Flare Seen from Sgr A*
Miller, J. M.; Nowak, M. A.; Grosso, N. +10 more
Starting in 2012, we began an unprecedented observational program focused on the supermassive black hole in the center of our Galaxy, Sgr A*, utilizing the High Energy Transmission Grating Spectrometer (HETGS) instrument on the Chandra X-Ray Observatory. These observations will allow us to measure the quiescent X-ray spectra of Sgr A* for the firs…
A New Low Magnetic Field Magnetar: The 2011 Outburst of Swift J1822.3-1606
Campana, S.; Tiengo, A.; Götz, D. +20 more
We report on the long-term X-ray monitoring with Swift, RXTE, Suzaku, Chandra, and XMM-Newton of the outburst of the newly discovered magnetar Swift J1822.3-1606 (SGR 1822-1606), from the first observations soon after the detection of the short X-ray bursts which led to its discovery, through the first stages of its outburst decay (covering the ti…
A Jet Break in the X-Ray Light Curve of Short GRB 111020A: Implications for Energetics and Rates
Troja, E.; Sakamoto, T.; Berger, E. +8 more
We present broadband observations of the afterglow and environment of the short GRB 111020A. An extensive X-ray light curve from Swift/XRT, XMM-Newton, and Chandra, spanning ~100 s to 10 days after the burst, reveals a significant break at δt ≈ 2 days with pre- and post-break decline rates of α X, 1 ≈ -0.78 and α X, 2 <~ -…
A Statistical Approach to Recognizing Source Classes for Unassociated Sources in the First Fermi-LAT Catalog
Ozaki, M.; Troja, E.; Caraveo, P. A. +174 more
The Fermi Large Area Telescope (LAT) First Source Catalog (1FGL) provided spatial, spectral, and temporal properties for a large number of γ-ray sources using a uniform analysis method. After correlating with the most-complete catalogs of source types known to emit γ rays, 630 of these sources are "unassociated" (i.e., have no obvious counterparts…
CLASH: Mass Distribution in and around MACS J1206.2-0847 from a Full Cluster Lensing Analysis
Donahue, Megan; Broadhurst, Tom; Koch, Patrick M. +45 more
We derive an accurate mass distribution of the galaxy cluster MACS J1206.2-0847 (z = 0.439) from a combined weak-lensing distortion, magnification, and strong-lensing analysis of wide-field Subaru BVR c I c z' imaging and our recent 16-band Hubble Space Telescope observations taken as part of the Cluster Lensing And Supernova…
XMM-Newton Detects a Hot Gaseous Halo in the Fastest Rotating Spiral Galaxy UGC 12591
Bregman, Joel N.; Anderson, Michael E.; Miller, Jon M. +1 more
We present our XMM-Newton observation of the fastest rotating spiral galaxy UGC 12591. We detect hot gas halo emission out to 80 kpc from the galaxy center, and constrain the halo gas mass to be smaller than 4.5 × 1011 M ⊙. We also measure the temperature of the hot gas as T = 0.64 ± 0.03 keV. Combining our x-ray constraints …
Discovery of Nine Gamma-Ray Pulsars in Fermi Large Area Telescope Data Using a New Blind Search Method
Caraveo, P. A.; de Luca, A.; Belfiore, A. +28 more
We report the discovery of nine previously unknown gamma-ray pulsars in a blind search of data from the Fermi Large Area Telescope (LAT). The pulsars were found with a novel hierarchical search method originally developed for detecting continuous gravitational waves from rapidly rotating neutron stars. Designed to find isolated pulsars spinning at…
The Swift Burst Alert Telescope Detected Seyfert 1 Galaxies: X-Ray Broadband Properties and Warm Absorbers
Veilleux, Sylvain; Kallman, T. R.; McKernan, Barry +1 more
We present results from an analysis of the broadband, 0.3-195 keV, X-ray spectra of 48 Seyfert 1-1.5 sources detected in the very hard X-rays with the Swift Burst Alert Telescope (BAT). This sample is selected in an all-sky survey conducted in the 14-195 keV band. Therefore, our sources are largely unbiased toward both obscuration and host galaxy …