Short Gamma Ray Bursts: do they follow the star formation rate?
Abstract
Possibly originating from neutron star-neutron star (NS-NS) mergers or black hole-neturon star (BH-NS) mergers, short GRBs (SGRBs) were the first events with associated gravitational wave observations. This association began a new era of multi-messenger astrophysics. Many recent papers in this field detail the cosmological distribution and evolution of the more numerous long GRBs (LGRBs). However, a critical issue needs to be solved for SGRBs: the identity of the true SGRB rate and whether or not this rate follows the star formation rate (SFR). Once we know the true SGRB rate, we can more precisely compute the expected number of SGRBs with associated gravitational waves. In this paper, we present a new determination of the luminosity and formation rate evolution of SGRBs using data from Swift with non-parametric and non-binning methods from Efron & Petrosian. These methods can readily combine samples with varied selection processes and are more powerful than the usual forward-fitting methods, especially for our sample which included a small number of sources. We assumed short with extended emission (SEE) and short GRBs descend from the same progenitor, thus we considered both samples together. To avoid the incompleteness of GRB samples due to unknown z we reduced the number of GRBs in our sample, allowing a relation to the parent group at the level of 89.9% in flux. Our results showed short GRBs have their formation rate evolution that does not match the GRB formation rate.
- Publication:
-
American Astronomical Society Meeting Abstracts #235
- Pub Date:
- January 2020
- Bibcode:
- 2020AAS...23544005D