A Universal Luminosity Function for Radio Supernova Remnants

We explore the supernova remnant (SNR) luminosity function (LF) at 20 
cm in 19 nearby galaxies ranging from the SMC to Arp 220. The radio LF 
constrains SNR evolution, diffusive shock acceleration and magnetic 
field amplification in more evolved remnants (at or after the Sedov 
time). We find that the LF is well fit by a power law that has constant 
index and scaling that depends linearly on star formation rate. It appears 
that radio supernova remnant populations are strikingly invariant across a 
wide range of galaxies, and can be well fit with current models of 
particle acceleration and magnetic field amplification. Our analysis 
implies that the efficiency of cosmic ray production is constant across 
galaxies.