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Short versus Long and Collapsars versus Non-collapsars: A Quantitative Classification of Gamma-Ray Bursts
Piran, Tsvi; Bromberg, Omer; Nakar, Ehud +1 more
Gamma-ray bursts (GRBs) are traditionally divided into long and short according to their durations (lg2 s). It was generally believed that this reflects a different physical origin: collapsars (long) and non-collapsars (short). We have recently shown that the duration distribution of collapsars is flat, namely, independent of the duration, at shor…
A Comprehensive Analysis of Fermi Gamma-Ray Burst Data. III. Energy-dependent T 90 Distributions of GBM GRBs and Instrumental Selection Effect on Duration Classification
Lin, Lin; Zhang, Bing; Liang, En-Wei +8 more
The durations (T 90) of 315 gamma-ray bursts (GRBs) detected with Fermi/GBM (8-1000 keV) up to 2011 September are calculated using the Bayesian Block method. We compare the T 90 distributions between this sample and those derived from previous/current GRB missions. We show that the T 90 distribution of this GRB sam…
Distribution of High-mass X-Ray Binaries in the Milky Way
Coleiro, Alexis; Chaty, Sylvain
Observations of the high-energy sky, particularly with the INTEGRAL satellite, have quadrupled the number of supergiant X-ray binaries observed in the Galaxy and revealed new populations of previously hidden high-mass X-ray binaries (HMXBs), raising new questions about their formation and evolution. The number of detected HMXBs of different types …
The Smooth Cyclotron Line in Her X-1 as Seen with Nuclear Spectroscopic Telescope Array
Hailey, Charles J.; Fürst, Felix; Klochkov, Dmitry +17 more
Her X-1, one of the brightest and best studied X-ray binaries, shows a cyclotron resonant scattering feature (CRSF) near 37 keV. This makes it an ideal target for a detailed study with the Nuclear Spectroscopic Telescope Array (NuSTAR), taking advantage of its excellent hard X-ray spectral resolution. We observed Her X-1 three times, coordinated w…
Superorbital Periodic Modulation in Wind-accretion High-mass X-Ray Binaries from Swift Burst Alert Telescope Observations
Corbet, Robin H. D.; Krimm, Hans A.
We report the discovery using data from the Swift-Burst Alert Telescope (BAT) of superorbital modulation in the wind-accretion supergiant high-mass X-ray binaries 4U 1909+07 (= X 1908+075), IGR J16418-4532, and IGR J16479-4514. Together with already known superorbital periodicities in 2S 0114+650 and IGR J16493-4348, the systems exhibit a monotoni…
An Accretion Model for the Anomalous X-Ray Pulsar 4U 0142+61
Zezas, A.; Dennerl, K.; Trümper, J. E. +2 more
We propose that the quiescent emission of anomalous X-ray pulsars/soft gamma-ray repeaters (AXPs/SGRs) is powered by accretion from a fallback disk, requiring magnetic dipole fields in the range 1012-1013 G, and that the luminous hard tails of their X-ray spectra are produced by bulk-motion Comptonization in the radiative sho…
Time-dependent Modeling of Pulsar Wind Nebulae
Tibolla, O.; Ferreira, S. E. S.; Kaufmann, S. +1 more
A spatially independent model that calculates the time evolution of the electron spectrum in a spherically expanding pulsar wind nebula (PWN) is presented, allowing one to make broadband predictions for the PWN's non-thermal radiation. The source spectrum of electrons injected at the termination shock of the PWN is chosen to be a broken power law.…
Polarimetry in the Hard X-Ray Domain with INTEGRAL SPI
Clark, D. J.; Jourdain, E.; Roques, J. P. +1 more
We present recent improvements in polarization analysis with the INTEGRAL SPI data. The SPI detector plane consists of 19 independent Ge crystals and can operate as a polarimeter. The anisotropy characteristics of Compton diffusions can provide information on the polarization parameters of the incident flux. By including the physics of the polariz…
An Archival Chandra and XMM-Newton Survey of Type 2 Quasars
Heckman, Timothy; Zakamska, Nadia L.; Ptak, Andrew +1 more
In order to investigate obscuration in high-luminosity type 2 active galactic nuclei (AGNs), we analyzed Chandra and XMM-Newton archival observations for 71 type 2 quasars detected at 0.05 < z < 0.73, which were selected based on their [O III] λ5007 emission lines. For 54 objects with good spectral fits, the observed hard X-ray luminosity ra…
Rapid Gamma-Ray Flux Variability during the 2013 March Crab Nebula Flare
Cheung, C. C.; Grove, J. E.; Hays, E. +5 more
We report on a bright flare in the Crab Nebula detected by the Large Area Telescope (LAT) on board the Fermi Gamma-ray Space Telescope. The period of significantly increased luminosity occurred in 2013 March and lasted for approximately two weeks. During this period, we observed flux variability on timescales of approximately 5 hr. The combined ph…