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…
Unidentified Line in X-Ray Spectra of the Andromeda Galaxy and Perseus Galaxy Cluster
Boyarsky, A.; Franse, J.; Iakubovskyi, D. +1 more
We report a weak line at 3.52 ±0.02 keV in x-ray spectra of the Andromeda galaxy and the Perseus galaxy cluster observed by the metal-oxide-silicon (MOS) and p -n (PN) CCD cameras of the XMM-Newton telescope. This line is not known as an atomic line in the spectra of galaxies or clusters. It becomes stronger towards the centers of the objects; is …
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…
The diversity of quasars unified by accretion and orientation
Shen, Yue; Ho, Luis C.
Quasars are rapidly accreting supermassive black holes at the centres of massive galaxies. They display a broad range of properties across all wavelengths, reflecting the diversity in the physical conditions of the regions close to the central engine. These properties, however, are not random, but form well-defined trends. The dominant trend is kn…
The role of the reflection fraction in constraining black hole spin.
Fabian, A. C.; Dauser, T.; Wilms, J. +2 more
In many active galaxies, the X-ray reflection features from the innermost regions of the accretion disc are relativistically distorted. This distortion allows us to measure parameters of the black hole such as its spin. The ratio in flux between the direct and the reflected radiation, the so-called reflection fraction, is determined directly from …
The incidence of obscuration in active galactic nuclei
Berta, S.; Magnelli, B.; Lutz, D. +22 more
We study the incidence of nuclear obscuration on a complete sample of 1310 active galactic nuclei (AGN) selected on the basis of their rest-frame 2-10 keV X-ray flux from the XMM-COSMOS survey, in the redshift range 0.3 < z < 3.5. We classify the AGN as obscured or unobscured on the basis of either the optical spectral properties and the ove…
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 …
The Sloan Digital Sky Survey quasar catalog: tenth data release
Finley, Hayley; Pâris, Isabelle; Petitjean, Patrick +47 more
We present the Data Release 10 Quasar (DR10Q) catalog from the Baryon Oscillation Spectroscopic Survey (BOSS) of the Sloan Digital Sky Survey III. The catalog includes all BOSS objects that were targeted as quasar candidates during the first 2.5 years of the survey and that are confirmed as quasars via visual inspection of the spectra, have lumino…
A state change in the low-mass X-ray binary XSS J12270-4859
Edwards, P. G.; Corbel, S.; Bassa, C. G. +10 more
Millisecond radio pulsars acquire their rapid rotation rates through mass and angular momentum transfer in a low-mass X-ray binary system. Recent studies of PSR J1824-2452I and PSR J1023+0038 have observationally demonstrated this link, and they have also shown that such systems can repeatedly transition back-and-forth between the radio millisecon…