NGC 2207/IC 2163: A Grazing Encounter with Large Scale Shocks
Abstract
Radio continuum, Spitzer infrared, optical, XMM X-ray, and ultraviolet observations are used to study large-scale shock fronts, young star complexes, and the galactic nuclei in the interacting galaxies NGC 2207/IC 2163. A large shock along the rim of the ocular oval in IC 2163 has produced vigorous star formation in a dusty environment, bright in the Spitzer 8 and 24 micron images. In the outer part of the companion side of NGC 2207, a large front attributed to halo scraping is bright in 6 cm and 20 cm radio continuum (RC) but not in tracers of star formation or X-rays. Values of the flux density ratio S(8 mu)/S(6 cm) of kpc-size star-forming clumps are compared with those of giant radio HII regions in M81. For the bright clumps in NGC 2207, the mean value of this ratio is the same as for the M81 HII regions, whereas for the bright clumps on the rim of the IC 2163 ocular oval, the mean value is nearly a factor of two greater. Global values of the ratios of IR to RC are significantly below the averages for large samples of galaxies. A mini-starburst on the outer arm of NGC 2207 is the most luminous FIR, RC, and Halpha source in the galaxy pair. We find evidence that a radio supernova occurred there in 2001. X-ray emission is detected from the nucleus of NGC 2207 and from nine discrete sources that are possible candidates for ULXs. One of these corresponds with the Type Ib SN 1999ec, which is also bright in the UV, and another may be a radio supernova or a background quasar. The X-ray luminosity of the NGC 2207 nucleus is log L(0.3-10.0 keV) = 40.6 ergs/s, which, together with its X-ray spectrum, suggests that this is a highly absorbed, low-luminosity AGN.
- Publication:
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American Astronomical Society Meeting Abstracts #221
- Pub Date:
- January 2013
- Bibcode:
- 2013AAS...22114606E