VizieR Online Data Catalog: Modelling of wind and supernovae shocks (Gupta+, 2020)

Observations show that in Sbc galaxies (Milky-Way-type) the ratio of thermonuclear to core-collapse SNe is ~1/3 (Mannucci et al. 2005A&A...433..807M). Adding thermonuclear SNRs, this indicates a ratio of SNRs to WTS γ-ray sources in our Galaxy of order 33-65.

We can check this argument by counting the SNRs and γ-ray bright clusters in a given volume. The size of the sampling volume is hard to decide, since γ-ray bright clusters are rare: there are only three γ-ray bright clusters near us, Cygnus at ~1.4kpc, Westerlund 1 at ~4kpc (Aharonian, Yang & de Ona Wilhelmi 2019NatAs...3..561A), and Westerlund 2 at ~5kpc (Yang et al. 2018A&A...611A..77Y). Therefore, it makes sense to use all these three and use a sphere of radius 5kpc around us. Counting the number of SNRs from the available catalogue, we find 124 of them within a distance of 5kpc (listed in Table C1).

(1 data file).