Search Publications
Swings between rotation and accretion power in a binary millisecond pulsar
Wieringa, M. H.; Campana, S.; Stella, L. +20 more
It is thought that neutron stars in low-mass binary systems can accrete matter and angular momentum from the companion star and be spun-up to millisecond rotational periods. During the accretion stage, the system is called a low-mass X-ray binary, and bright X-ray emission is observed. When the rate of mass transfer decreases in the later evolutio…
Constraining light dark matter with diffuse X-ray and gamma-ray observations
Essig, Rouven; Kuflik, Eric; Volansky, Tomer +2 more
We present constraints on decaying and annihilating dark matter (DM) in the 4 keV to 10 GeV mass range, using published results from the satellites HEAO-1, INTEGRAL, COMPTEL, EGRET, and the Fermi Gamma-ray Space Telescope. We derive analytic expressions for the gamma-ray spectra from various DM decay modes, and find lifetime constraints in the ran…
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…
Multiwavelength campaign on Mrk 509. XII. Broad band spectral analysis
Kaastra, J. S.; Kriss, G. A.; Bianchi, S. +12 more
The origin of the different spectral components present in the high-energy (UV to X-rays/gamma-rays) spectra of Seyfert galaxies is still being debated a lot. One of the major limitations, in this respect, is the lack of really simultaneous broad-band observations that allow us to disentangle the behavior of each component and to better constrain …
X-ray follow-ups of XSS J12270-4859: a low-mass X-ray binary with gamma-ray Fermi-LAT association
Mukai, K.; Belloni, T.; de Martino, D. +10 more
Context. XSS J1227.0-4859 is a peculiar, hard X-ray source recently positionally associated to the Fermi-LAT source 1FGL J1227.9-4852/2FGL J1227.7-4853. Multi-wavelength observations have added information on this source, indicating a low-luminosity low-mass X-ray binary (LMXB), but its nature is still unclear.
Aims: To progress in our unders…
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…
The polarized gamma-ray burst GRB 061122
Covino, S.; Götz, D.; Bošnjak, Ž. +2 more
We report on the polarization measure, obtained with IBIS on board INTEGRAL, of the prompt emission of GRB 061122. Over an 8 s interval containing the brightest part of the gamma-ray burst (GRB) we put a lower limit on its polarization fraction of 60 per cent at 68 per cent confidence level (c.l.) and of 33 per cent at 90 per cent c.l. on the 250-…
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 …
Population of persistent high-mass X-ray binaries in the Milky Way
Tsygankov, S. S.; Lutovinov, A. A.; Revnivtsev, M. G. +1 more
We present results of the study of persistent high-mass X-ray binaries (HMXBs) in the Milky Way, obtained from the deep INTEGRAL Galactic plane survey. This survey provides us a new insight into the population of HMXBs because almost half of the whole sample consists of sources discovered with INTEGRAL. It is demonstrated for the first time that t…
On timing and spectral characteristics of the X-ray pulsar 4U 0115+63: Evolution of the pulsation period and the cyclotron line energy
Tsygankov, S. S.; Lutovinov, A. A.; Boldin, P. A.
An overview of the results of observations for the transient X-ray pulsar 4U 0115+63, amember of a binary system with a Be star, since its discovery to the present day (∼40 years) based on data from more than dozen observatories and instruments is presented. An overall light curve and the history of change in the spin frequency of the neutron star…