X-ray observations of hot gas in a number of nearby galaxies have revealed a tight spatial correlation between X-ray superbubbles and sites of recent star formation. Dr. Eric Wilcots (University of Wisconsin-Madison) will obtain sensitive radio continuum observations of these same galaxies in order to detect large numbers of radio supernova remnants (SNRs) and correlate their energies and spatial distribution with the observed X-ray superbubbles. The result will be a straightforward test of the proposition that superbubbles trace the distribution of recent supernova explosions, as well as a measure of the extent to which the cosmic ray energy traces the thermal energy of the superbubble. The new set of radio continuum observations will also result in the most sensitive searches for SNRs to date and will yield a well defined SNR luminosity function and spectral index distribution for each galaxy.
This scientific program is a broad effort to understand the relationships between SNRs, superbubbles, and the overall evolution of the interstellar medium in disk galaxies. The results of this program will show the extent to which SNRs and X-ray superbubbles are spatially and energetically correlated, and accurately depict the SNR luminosity function for a sample of disk galaxies with a range of star formation rates.
In addition to the research goals, this program will support the training of one full time graduate student and some 6 to 10 undergraduates over the course of its duration. This program will also provide key support of the outreach activities associated with University of Wisconsin Space Place, the off-campus outreach center of the Department of Astronomy.
