Search Publications
Determination of the Mass of IGR J17091-3624 from "Spectro-temporal" Variations during the Onset Phase of the 2011 Outburst
Nandi, A.; Mandal, S.; Iyer, N.
The 2011 outburst of the black hole candidate IGR J17091-3624 followed the canonical track of state transitions along with the evolution of quasi-periodic oscillation (QPO) frequencies before it began exhibiting various variability classes similar to GRS 1915+105. We use this canonical evolution of spectral and temporal properties to determine the…
Spectral State Dependence of the 0.4-2 MeV Polarized Emission in Cygnus X-1 Seen with INTEGRAL/IBIS, and Links with the AMI Radio Data
Grinberg, Victoria; Pottschmidt, Katja; Wilms, Jörn +6 more
Polarization of the ≳ 400 keV hard tail of the microquasar Cygnus X-1 has been independently reported by INTEGRAL/Imager on Board the INTEGRAL Satellite (IBIS), and INTEGRAL/SPectrometer on INTEGRAL and interpreted as emission from a compact jet. These conclusions were, however, based on the accumulation of all INTEGRAL data regardless of the spec…
Gamma-rays from Type Ia Supernova SN2014J
Sunyaev, R.; Churazov, E.; Bikmaev, I. +8 more
The whole set of INTEGRAL observations of Type Ia supernova SN 2014J, covering the period 19-162 days after the explosion, has been analyzed. For spectral fitting the data are split into early and late periods covering days 19-35 and 50-162, respectively, optimized for 56Ni and 56Co lines. As expected for the early period, mu…
The Galactic 26Al Emission Map as Revealed by INTEGRAL SPI
Jourdain, Elisabeth; Roques, Jean-Pierre; Bouchet, Laurent
Diffuse emission is often challenging since it is undetectable by most instruments, which are generally dedicated to point-source studies. The 26Al emission is a good illustration: the only available 26Al map to date has been released, more than 15 yr ago, thanks to the COMPTEL instrument. However, at the present time, the SP…
Gamma-Ray Flaring Activity from the Gravitationally Lensed Blazar PKS 1830-211 Observed by Fermi LAT
Troja, E.; Caraveo, P. A.; Bechtol, K. +125 more
The Large Area Telescope (LAT) on board the Fermi Gamma-ray Space Telescope routinely detects the MeV-peaked flat-spectrum radio quasar PKS 1830-211 (z = 2.507). Its apparent isotropic γ-ray luminosity (E > 100 MeV), averaged over ~3 years of observations and peaking on 2010 October 14/15 at 2.9 × 1050 erg s-1, makes it am…
The INTEGRAL/SPI view of A0535+26 during the Giant Outburst of 2011 February
Jourdain, E.; Roques, J. P.; Sartore, N.
A0535+26 is a slowly rotating pulsar accreting from the wind of a massive Be star and exhibits two cyclotron absorption lines in its X-ray spectrum, at about 45 and 100 keV, respectively. Unlike similar sources, no significant variations of the energy of its cyclotron lines with flux have been observed to date. The bright outburst of 2011 February…
First INTEGRAL Observations of V404 Cygni during the 2015 Outburst: Spectral Behavior in the 20-650 keV Energy Range
Ubertini, Pietro; Bazzano, Angela; Jourdain, Elisabeth +3 more
In 2015 June, the source V404 Cygni (= GS2023+38) underwent an extraordinary outburst. We present the results obtained during the first revolution dedicated to this target by the INTEGRAL mission and focus on the spectral behavior in the hard X-ray domain, using both SPI and IBIS instruments. The source exhibits extreme variability and reaches flu…
3C 273 with NuSTAR: Unveiling the Active Galactic Nucleus
Hailey, Charles J.; Fabian, Andrew C.; Brenneman, Laura W. +17 more
We present results from a 244 ks NuSTAR observation of 3C 273 obtained during a cross-calibration campaign with the Chandra, INTEGRAL, Suzaku, Swift, and XMM-Newton observatories. We show that the spectrum, when fit with a power-law model using data from all observatories except INTEGRAL over the 1-78 keV band, leaves significant residuals in the …
Phase-resolved NuSTAR and Swift-XRT Observations of Magnetar 4U 0142+61
An, Hongjun; Kaspi, Victoria M.; Guillot, Sebastien +12 more
We present temporal and spectral analysis of simultaneous 0.5-79 keV Swift-XRT and Nuclear Spectroscopic Telescope Array observations of the magnetar 4U 0142+61. The pulse profile changes significantly with photon energy between 3 and 35 keV. The pulse fraction increases with energy, reaching a value of ≈20%, similar to that observed in 1E 1841-04…
Dark Matter Line Emission Constraints from NuSTAR Observations of the Bullet Cluster
Harrison, F. A.; Hornstrup, A.; Stern, D. +10 more
Some dark matter candidates, e.g., sterile neutrinos, provide observable signatures in the form of mono-energetic line emission. We present the first search for dark matter line emission in the 3-80 {keV} range in a pointed observation of the Bullet Cluster with NuSTAR. We do not detect any significant line emission and instead we derive upper lim…