The Host Galaxies of Short-Duration Gamma-Ray Bursts: Luminosities, Metallicities, and Star Formation Rates

TL;DR

This study investigates the properties of host galaxies of short-duration gamma-ray bursts, revealing they are generally more luminous, metal-rich, and have lower specific star formation rates than long GRB hosts, suggesting older progenitor populations.

Contribution

It provides the first comprehensive comparison of short GRB host galaxy properties with those of long GRBs and field galaxies, highlighting differences in luminosity, metallicity, and star formation activity.

Findings

Short GRB hosts have luminosities of 0.1-1.5 L*.

Star formation rates are around 0.2-6 M_sun/yr.

Metallicities are approximately 12+log(O/H)~8.5-8.9.

Abstract

The association of some short-duration gamma-ray bursts (GRBs) with elliptical galaxies established that their progenitors, unlike those of long GRBs, belong to an old stellar population. However, the majority of short GRBs appear to occur in star forming galaxies, raising the possibility that some progenitors are related to recent star formation activity. Here we present optical spectroscopy of these hosts and measure their luminosities, star formation rates, and metallicities. We find luminosities of L_B~0.1-1.5 L*, star formation rates of SFR~0.2-6 M_sun/yr, and metallicities of 12+log(O/H)~8.5-8.9 (Z~0.6-1.6 Z_sun). A detailed comparison to the hosts of long GRBs reveals systematically higher luminosities, lower specific star formation rates (SFR/L_B) by about an order of magnitude, and higher metallicities by about 0.6 dex. The K-S probability that the short and long GRB hosts are drawn from the same underlying galaxy distribution is only 10^-3. On the other hand, short GRB hosts exhibit excellent agreement with the specific star formation rates and the luminosity-metallicity relation of field galaxies at z~0.1-1. We thus conclude that short GRB hosts are not dominated by young stellar populations like long GRBs hosts. Instead, short GRB hosts appear to be drawn uniformly from the underlying galaxy distribution, indicating that the progenitors have a wide age distribution of several Gyr.