Isolated X-Ray-Infrared Sources in the Region of Interaction of the Supernova Remnant IC 443 with a Molecular Cloud

BYKOV, A. M.; KRASSILCHTCHIKOV, A. M.; UVAROV, YU. A.; BLOEMEN, H.; BOCCHINO, F.; DUBNER, G. M.; GIACANI, E. B.; PAVLOV, G. G.

Astrophysical Journal

University of Chicago Press

Año: 2008 vol. 676 p. 1050 - 1064

0004-637X

The nature of the extended hard X-ray source XMMU J061804.3+222732 and its surroundings is investigated using XMM-Newton, Chandra, and Spitzer observations. This source is located in an interaction region of the IC 443 supernova remnant with a neighboring molecular cloud. The X-ray emission consists of a number of bright clumps embedded in an extended structured nonthermal X-ray nebula larger than 30" in size. Some clumps show evidence for line emission at ~1.9 and ~3.7 keV at the 99% confidence level. Large-scale diffuse radio emission of IC 443 passes over the source region, with an enhancement near the source. An IR source of about 14´´×7´´ size is prominent in the 24, 70, and 2.2 μm bands, adjacent to a putative Si K-shell X-ray line emission region. The observed IR/X-ray morphology and spectra are consistent with those expected for J/C-type shocks of different velocities driven by fragmented supernova ejecta colliding with the dense medium of a molecular cloud. The IR emission of the source detected by Spitzer can be attributed to both continuum emission from an H II region created by the ejecta fragment and line emission excited by shocks. This source region in IC 443 may be an example of a rather numerous population of hard X-ray/IR sources created by supernova explosions in the dense environment of star-forming regions. Alternative Galactic and extragalactic interpretations of the observed source are also discussed.