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arXiv · 0707.2005

INTEGRAL-ISGRI observations of the CygOB2 region: earching for hard X-ray point sources in a region containing several non-thermal emitting massive stars

M. De Becker·G. Rauw·J. M. Pittard·H. Sana·I. R. Stevens·G. E. Romero
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Abstract

Aims: We analyze INTEGRAL-ISGRI data in order to probe the hard X-ray emission (above 20 keV) from point sources in the Cyg OB2 region and to investigate the putative non-thermal high-energy emission from early-type stars (Wolf-Rayet and O-type stars). Among the targets located in the field of view, we focus on the still unidentified EGRET source 3EG 2033+4118 that may be related to massive stars known to produce non-thermal emission in the radio domain, and on the wide colliding-wind binary WR 140. Methods: Using a large set of data obtained with the IBIS-ISGRI imager onboard INTEGRAL, we run the OSA software package in order to find point sources in the fully coded field of view of the instrument. Results: Our data do not allow the detection of a lower-energy counterpart of 3EG J2033+4118 nor of any other new point sources in the field of view, and we derive upper limits on the high-energy flux for a few targets: 3EG J2033+4118, TeV J2032+4130, WR140, WR146 and WR147. The results are discussed in the context of the multiwavelength investigation of these objects. Conclusions: The upper limits derived are valuable constraints for models aimed at understanding the acceleration of particles in non-thermal emitting massive stars, and of the still unidentified very-high gamma-ray source TeV J2032+4130.

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M. De Becker, G. Rauw, J. M. Pittard, H. Sana, I. R. Stevens, G. E. Romero. 2007-07-13. INTEGRAL-ISGRI observations of the CygOB2 region: earching for hard X-ray point sources in a region containing several non-thermal emitting massive stars. https://doi.org/10.1051/0004-6361:20077734

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