Search Publications
Swift BAT Survey of AGNs
Gehrels, N.; Mushotzky, R. F.; Barthelmy, S. +5 more
We present the results of the analysis of the first 9 months of data of the Swift BAT survey of AGNs in the 14-195 keV band. Using archival X-ray data or follow-up Swift XRT observations, we have identified 129 (103 AGNs) of 130 objects detected at | b| > 15° and with significance >4.8 σ. One source remains unidentified. These same X-ray dat…
Inverse Compton Origin of the Hard X-Ray and Soft Gamma-Ray Emission from the Galactic Ridge
Bouchet, L.; Porter, Troy A.; Strong, Andrew W. +2 more
A recent redetermination of the nonthermal component of the hard X-ray to soft γ-ray emission from the Galactic ridge, using the SPI instrument on the International Gamma-Ray Astrophysics Laboratory (INTEGRAL), is shown to be well reproduced as inverse Compton emission from the interstellar medium. Both cosmic-ray primary electrons and secondary e…
Cosmic X-Ray Background and Earth Albedo Spectra with Swift BAT
Greiner, J.; Strong, A. W.; Ajello, M. +8 more
We use Swift BAT Earth occultation data at different geomagnetic latitudes to derive a sensitive measurement of the cosmic X-ray background (CXB) and of the Earth albedo emission in the 15-200 keV band. We compare our CXB spectrum with recent (INTEGRAL, BeppoSAX) and past results (HEAO-1) and find good agreement. Using an independent measurement o…
Polarization of the Crab Pulsar and Nebula as Observed by the INTEGRAL/IBIS Telescope
Grenier, I. A.; Laurent, P.; Lebrun, F. +2 more
Neutron stars generate powerful winds of relativistic particles that form bright synchrotron nebulae around them. Polarimetry provides a unique insight into the geometry and magnetic configuration of the wind, but high-energy measurements have failed until recently. The INTEGRAL/IBIS telescope has been used in its Compton mode to search for linear…
Resonant Cyclotron Scattering in Magnetars' Emission
Götz, D.; Rea, N.; Lyutikov, M. +2 more
We present a systematic fit of a model of resonant cyclotron scattering (RCS) to the X-ray data of 10 magnetars, including canonical and transient anomalous X-ray pulsars (AXPs) and soft gamma repeaters (SGRs). In this scenario, nonthermal magnetar spectra in the soft X-rays (i.e., below ~10 keV) result from resonant cyclotron scattering of the th…
INTEGRAL SPI All-Sky View in Soft Gamma Rays: A Study of Point-Source and Galactic Diffuse Emission
Bouchet, L.; Terrier, R.; Diehl, R. +4 more
We have processed the data accumulated with the INTEGRAL SPI instrument over 4 years (~51 Ms) to study the morphology of the Galactic "diffuse" emission in the 20 keV to 8 MeV energy range. To achieve this, we simultaneously derived an all-sky census of emitting sources and images of the Galactic ridge (GR) emission. In the central radian, the res…
Characterizing the Nonthermal Emission of Cassiopeia A
Vink, J.; Helder, E. A.
We report on our analysis of the 1 Ms Chandra observation of the supernova remnant Cas A in order to localize, characterize, and quantify the nonthermal X-ray emission. More specifically, we investigated whether the X-ray synchrotron emission from the inside of the remnant is from the outward shock, but projected toward the inner ring, or from the…
Discovery of the Radio and X-Ray Counterpart of TeV γ-Ray Source HESS J1731-347
Leahy, D. A.; Jiang, B.; Haverkorn, M. +1 more
We discover a faint shell-type radio and X-ray source, G353.6-0.7, associated with HESS J1731-347. G353.6-0.7 is likely an old supernova remnant (SNR), based on radio (0.8, 1.4, and 5 GHz), infrared (8 µm from the GLIMPSE Legacy Project and 21 µm from the Midcourse Space Experiment), and X-ray (0.1-2.4 keV from the ROSAT survey and 5-2…
A Giant Flare from a Soft Gamma Repeater in the Andromeda Galaxy (M31)
Hurley, K.; von Kienlin, A.; Frederiks, D. D. +6 more
The light curve, energy spectra, energetics, and IPN localization of an exceedingly intense, short-duration, hard-spectrum burst, GRB 070201, obtained from Konus-Wind, INTEGRAL (SPI-ACS), and MESSENGER data are presented. The total fluence of the burst and the peak flux are S = 2.00+ 0.10-0.26 × 10-5 erg cm-2<…
3C 454.3 Reveals the Structure and Physics of Its "Blazar Zone"
Madejski, Greg M.; Sikora, Marek; Moderski, RafaŁ
Recent multiwavelength observations of 3C 454.3, in particular during its giant outburst in 2005, put severe constraints on the location of the "blazar zone," its dissipative nature, and high-energy radiation mechanisms. As the optical, X-ray, and millimeter light curves indicate, a significant fraction of the jet energy must be released in the vi…