We have begun a program to identify and characterize the supernova remnant (SNR) population in the face-on giant spiral galaxy M101 (d=6.8 Mpc, 0.1"=3.3 pc), using Hubble Space Telescope imaging. Our Cycle 21 program leverages archival ACS/WFC deep H-alpha and continuum imaging for four fields by obtaining new WFC3 [S II] and [O III] imaging; also, one new field has been completely done with WFC3. The region covered extends to ~12 kpc, but is asymmetrical with respect to the nucleus. Of the 93 SNR candidates known from ground-based imaging, 31 are within the new WFC3 coverage and all but two are confirmed. Additionally, we have identified 23 new strong SNR candidates and another 37 second-tier candidates within the WFC3 footprint. Thus, we have likely more than doubled the number of SNR candidates in the sampled region. We measure diameters for the sample and compare to other galaxy samples such as in M83 (which has more small diameter SNRs). At least 25 of the sources appear to have X-ray counterparts in deep Chandra data. Interestingly, no strong candidates for young, ejecta-dominated (Cas A-like) SNRs have been found in the sample to date. Scaling up to the entire galaxy, there should be well over 200 detectable SNRs in M101 if a full survey was performed. We acknowledge support from STScI grant HST-GO-13361-01-A to the Johns Hopkins University.
American Astronomical Society Meeting Abstracts #227
- Pub Date:
- January 2016