Galaxy Clusters Associated with Short GRBs. II. Predictions for the Rate of Short GRBs in Field and Cluster Early‐Type Galaxies

Abstract

We determine the relative rates of short GRBs in cluster and field early-type galaxies as a function of the age probability distribution of their progenitors, P() / n . This analysis takes advantage of the difference in the growth of stellar mass in clusters and in the field, which arises from the combined effects of the galaxy stellar mass function, the early-type fraction, and the dependence of star formation history on mass and environment. This approach complements the use of the early-to late-type host galaxy ratio, with the added benefit that the star formation histories of early-type galaxies are simpler than those of late-type galaxies, and any systematic differences between progenitors in early-and late-type galaxies are removed. We find that the ratio varies from R cluster /R Beld $ 0:5 for n ¼ À2 to $3 for n ¼ 2. Current observations indicate a ratio of about 2, corresponding to n $ 0 Y1. This is similar to the value inferred from the ratio of short GRBs in early-and late-type hosts, but it differs from the value of n % À1 for neutron star (NS) binaries in the Milky Way. We stress that this general approach can be easily modified with improved knowledge of the effects of environment and mass on the build-up of stellar mass, as well as the effect of globular clusters on the short GRB rate. It can also be used to assess the age distribution of Type Ia supernova progenitors.

Short Gamma-ray bursts: a bimodal origin?

“…We have shown that current Swift data seem to point towards a dual nature of SGRB formation: low‐ z SGRBs may arise from the coalescence of DNSs forming in GCs through dynamical collisions, whereas high‐ z bursts can represent the end‐result of DNS mergers born in the field from primordial massive binary stars. A way to falsify this bimodality is by considering the correlation between SGRBs and the host galaxy type (Gal‐Yam et al 2005; Berger et al 2007b; Shin & Berger 2007; Zheng & Ramirez‐Ruiz 2007). We expect that SGRBs from the GC channel should be found preferentially in early‐type galaxies where the bulk of GCs resides, although we cannot completely exclude a few in spirals.…”

Short-Duration Gamma-Ray Bursts

“…The first short GRB with an afterglow detection, GRB 050509b, was most likely associated with a galaxy cluster at z = 0.225 (Gehrels et Since the stellar populations in galaxy clusters are systematically older than in field galaxies, the fraction of short GRBs in clusters can be used as an indicator of the age distribution (Shin & Berger 2007). At present, the fraction of short GRBs in clusters appears to be ∼ 10% (Berger et al 2007b), at the low end of the fraction of cosmic stellar mass in clusters of about 10 − 20% (Fukugita, Hogan & Peebles 1998; Eke et al 2005).…”

The Excess Density of Field Galaxies near z=0.56 around the Gamma-Ray Burst GRB021004 Position

“…If this excess of intervening systems is real, it should be possible to find an excess of GRB field galaxies around GRB positions, although a preliminary study has revealed no anomalous clustering of galaxies (in comparison with distribution of quasar) at the estimated median redshift of about 0.3 around GRB line of sights [17]. Furthermore, it has been proposed that the majority of shortduration GRBs in early-type galaxies will occur in clusters and three such relationships have been already found [38].…”