Program: GN-2017A-FT-7

To study SNRs as a class of objects, large uniform samples are required. Here we propose to use GMOS to obtain images in [S II], Ha and an associated continuum band to identify the SNR population of M51. While we have already identified some 80 SNRs in M51 using HST, our HST study is heavily biased towards small-diameter, high-surface-brightness objects and is not directly comparable to SNR samples in other nearby galaxies. Observations with GMOS will remove this bias, and enable us to compare the X-ray, optical, and radio properties of a large number of SNRs, all at the same distance and with relatively low foreground absorption. To understand the role of SNe in the evolution of galaxies, it is necessary to probe the multiwavelength properties of SNRs in a range of galaxies with different star formation rates and histories. Through this proposal, M51 will join only a handful of other nearby, face-on spirals with sufficient X-ray, radio, and optical data to enable such a study. We will use the combined dataset to understand what environmental and physical factors cause SNRs to appear as the do, given their large brightness variations at similar diameters (seen in all three wavelength bands) and the minimal correlation in brightness between bands.