Search Publications
The Man behind the Curtain: X-Rays Drive the UV through NIR Variability in the 2013 Active Galactic Nucleus Outburst in NGC 2617
Im, M.; Choi, C.; Yoon, Y. +44 more
After the All-Sky Automated Survey for SuperNovae discovered a significant brightening of the inner region of NGC 2617, we began a ~70 day photometric and spectroscopic monitoring campaign from the X-ray through near-infrared (NIR) wavelengths. We report that NGC 2617 went through a dramatic outburst, during which its X-ray flux increased by over …
Detection of an Unidentified Emission Line in the Stacked X-Ray Spectrum of Galaxy Clusters
Bulbul, Esra; Loewenstein, Michael; Markevitch, Maxim +3 more
We detect a weak unidentified emission line at E = (3.55-3.57) ± 0.03 keV in a stacked XMM-Newton spectrum of 73 galaxy clusters spanning a redshift range 0.01-0.35. When the full sample is divided into three subsamples (Perseus, Centaurus+Ophiuchus+Coma, and all others), the line is seen at >3σ statistical significance in all three independent…
Improved Reflection Models of Black Hole Accretion Disks: Treating the Angular Distribution of X-Rays
Reynolds, C. S.; García, J.; Dauser, T. +8 more
X-ray reflection models are used to constrain the properties of the accretion disk, such as the degree of ionization of the gas and the elemental abundances. In combination with general relativistic ray tracing codes, additional parameters like the spin of the black hole and the inclination to the system can be determined. However, current reflect…
A Panchromatic View of the Restless SN 2009ip Reveals the Explosive Ejection of a Massive Star Envelope
Im, M.; Choi, C.; Campana, S. +54 more
The double explosion of SN 2009ip in 2012 raises questions about our understanding of the late stages of massive star evolution. Here we present a comprehensive study of SN 2009ip during its remarkable rebrightenings. High-cadence photometric and spectroscopic observations from the GeV to the radio band obtained from a variety of ground-based and …
Direct Measurements of Dust Attenuation in z ~ 1.5 Star-forming Galaxies from 3D-HST: Implications for Dust Geometry and Star Formation Rates
van Dokkum, Pieter G.; Franx, Marijn; Conroy, Charlie +11 more
The nature of dust in distant galaxies is not well understood, and until recently few direct dust measurements have been possible. We investigate dust in distant star-forming galaxies using near-infrared grism spectra of the 3D-HST survey combined with archival multi-wavelength photometry. These data allow us to make a direct comparison between du…
Short GRB 130603B: Discovery of a Jet Break in the Optical and Radio Afterglows, and a Mysterious Late-time X-Ray Excess
Berger, E.; Foley, R. J.; Chornock, R. +13 more
We present radio, optical/NIR, and X-ray observations of the afterglow of the short-duration Swift and Konus-Wind GRB 130603B, and uncover a break in the radio and optical bands at ≈0.5 day after the burst, best explained as a jet break with an inferred jet opening angle of ≈4°-8°. GRB 130603B is only the third short GRB with a radio afterglow det…
16 yr of RXTE Monitoring of Five Anomalous X-Ray Pulsars
Kaspi, Victoria M.; Dib, Rim
We present a summary of the long-term evolution of various properties of the five non-transient anomalous X-ray pulsars (AXPs) 1E 1841-045, RXS J170849.0-400910, 1E 2259+586, 4U 0142+61, and 1E 1048.1-5937, regularly monitored with RXTE from 1996 to 2012. We focus on three properties of these sources: the evolution of the timing, pulsed flux, and …
The Role of Stellar Feedback in the Dynamics of H II Regions
Ramirez-Ruiz, Enrico; Prochaska, J. Xavier; Bolatto, Alberto D. +3 more
Stellar feedback is often cited as the biggest uncertainty in galaxy formation models today. This uncertainty stems from a dearth of observational constraints as well as the great dynamic range between the small scales (lsim1 pc) where the feedback originates and the large scales of galaxies (gsim1 kpc) that are shaped by this feedback. To bridge …
Evidence for Particle Re-acceleration in the Radio Relic in the Galaxy Cluster PLCKG287.0+32.9
Nonino, M.; van Weeren, R. J.; Röttgering, H. J. A. +5 more
Radio relics are diffuse radio sources observed in galaxy clusters, probably produced by shock acceleration during cluster-cluster mergers. Their large size, of the order of 1 Mpc, indicates that the emitting electrons need to be (re)accelerated locally. The usually invoked diffusive shock acceleration models have been challenged by recent observa…
Abundant Molecular Gas and Inefficient Star Formation in Intracluster Regions: Ram Pressure Stripped Tail of the Norma Galaxy ESO137-001
Combes, Françoise; Sun, Ming; Jáchym, Pavel +2 more
For the first time, we reveal large amounts of cold molecular gas in a ram-pressure-stripped tail, out to a large "intracluster" distance from the galaxy. With the Actama Pathfinder EXperiment (APEX) telescope, we have detected 12CO(2-1) emission corresponding to more than 109 M ⊙ of H2 in three Hα brigh…