Hard X-ray emission clumps in the γ-Cygni supernova remnant: An INTEGRAL-ISGRI view
Chevalier, R. A.; Terrier, R.; Rauw, G.; Hermsen, W.; Bykov, A. M.; Krassilchtchikov, A. M.; Uvarov, Yu. A.; Bloemen, H.; Gustov, M. Yu.; Lebrun, F.; Lozinskaya, T. A.; Smirnova, T. V.; Sturner, S. J.; Swings, J. -P.; Toptygin, I. N.
Russia, Netherlands, United States, France, Belgium
Abstract
Spatially resolved images of the galactic supernova remnant G78.2+2.1 (γ-Cygni) in hard X-ray energy bands from 25 keV to 120 keV are obtained with the IBIS-ISGRI imager aboard the International Gamma-Ray Astrophysics Laboratory INTEGRAL. The images are dominated by localized clumps of about ten arcmin in size. The flux of the most prominent North-Western (NW) clump is (1.7±0.4)×10-11 erg cm-2 s-1 in the 25-40 keV band. The observed X-ray fluxes are in agreement with extrapolations of soft X-ray imaging observations of γ-Cyg by ASCA GIS and spatially unresolved RXTE PCA data. The positions of the hard X-ray clumps correlate with bright patches of optical line emission, possibly indicating the presence of radiative shock waves in a shocked cloud. The observed spatial structure and spectra are consistent with model predictions of hard X-ray emission from nonthermal electrons accelerated by a radiative shock in a supernova interacting with an interstellar cloud, but the powerful stellar wind of the O9V star HD 193322 is a plausible candidate for the NW source as well.