A Search for X-ray Counterparts to Candidate Radio Supernova Remnants in the Galaxy NGC 4258
Abstract
We present a search for X-ray counterparts to known candidate radio supernova remnants (SNRs) in the nearby spiral galaxy NGC 4258. This galaxy features an enhanced rate of star formation compared to normal spirals: numerous discrete radio sources - including the candidate radio SNRs - were identified by a survey conducted by Hyman et al. (2001) at 6cm and 20cm: the radio luminosities of several of these sources as calculated by Hyman et al. 2001 exceed the radio luminosity of the Galactic SNR Cassiopeia A. To conduct our search, we have downloaded archival X-ray observations made of this galaxy using the Chandra X-ray Observatory: the superior angular resolution attained by Chandra (approximately one arcsecond) is essential for identifying X-ray counterparts to the candidate radio SNRs with significant positional confidence. Results from our analysis have identified two possible X-ray binary sources associated (within 2.5 arcseconds) with highly luminous candidate radio SNRs identified by Hyman et al. 2001. We have analyzed the properties of analogous extragalactic X-ray binary systems with candidate radio SNR counterparts -- namely MF16 and X-7 in NGC 6946 and M81 respectively -- as well as the Galactic X-ray binary/radio SNR system SS433/W50 to provide a context for these systems found in NGC 4258. We have also searched for other candidate X-ray SNRs based on their soft X-ray spectra sources coincident with regions of H-alpha emission in the galaxy NGC 4258. Results will be presented and discussed.
- Publication:
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American Astronomical Society Meeting Abstracts #219
- Pub Date:
- January 2012
- Bibcode:
- 2012AAS...21923921G