Distances, Radial Distribution, and Total Number of Galactic Supernova Remnants

We present a table of 215 supernova remnants (SNRs) with distances. New distances are found to SNR G51.26 + 0.11 of 6.6 +/- 1.7 kpc using H i absorption spectra and to five other SNRs using maser/molecular cloud associations. We recalculate the distances and errors to all SNRs using a consistent rotation curve and provide errors where they were not previously estimated. This results in a significant distance revisions for 20 SNRs. Because of observational constraints and selection effects, there is an apparent deficit of observed number of Galactic SNRs. To investigate this, we employ two methods. The first method applies correction factors for the selection effects to derive the radial density distribution. The second method compares functional forms for the SNR surface density and selection function against the data to find which functions are consistent with the data. The total number of SNRs in the Galaxy is similar to 3500 (Method 1) or in the range from similar to 2400 to similar to 5600 (Method 2). We conclude that the current observed number of SNRs is not yet complete enough to give a well-determined total SNR number or radial density function.

Automated summary

This study presents a table of distances for 215 supernova remnants (SNRs) and recalculates the distances for some of them. Due to observational constraints and selection effects, the observed number of SNRs is not sufficient to determine the total number or radial density function.