GRB 080517: A local, low luminosity GRB in a dusty galaxy at z=0.09

TL;DR

This paper analyzes the host galaxy of a nearby, low luminosity gamma-ray burst, revealing active star formation, significant dust obscuration, and possible galaxy interaction, contributing valuable data on local GRB environments.

Contribution

It provides detailed photometric and spectroscopic analysis of a rare, local GRB host, including radio detection and star formation insights, expanding understanding of low luminosity GRB environments.

Findings

Host galaxy at z=0.089 is forming stars rapidly (~16 Msun/yr).

Galaxy shows high dust obscuration with E(B-V)>1.

Presence of a companion galaxy suggests interaction-triggered star formation.

Abstract

We present an analysis of the photometry and spectroscopy of the host galaxy of Swift-detected GRB 080517. From our optical spectroscopy, we identify a redshift of z = 0.089 +/- 0.003, based on strong emission lines, making this a rare example of a very local, low luminosity, long gamma ray burst. The galaxy is detected in the radio with a flux density of S(4.8GHz) =0.22 +/- 0.04mJy - one of relatively few known GRB hosts with a securely measured radio flux. Both optical emission lines and a strong detection at 22 um suggest that the host galaxy is forming stars rapidly, with an inferred star formation rate ~16 Msun/yr and a high dust obscuration (E(B-V )>1, based on sight-lines to the nebular emission regions). The presence of a companion galaxy within a projected distance of 25 kpc, and almost identical in redshift, suggests that star formation may have been triggered by galaxy-galaxy interaction. However, fitting of the remarkably flat spectral energy distribution from the ultraviolet through to the infrared suggests that an older, 500Myr post-starburst stellar population is present along with the ongoing star formation. We suggest that that the host galaxy of GRB 080517 is a valuable addition to the still very small sample of well-studied local gamma-ray burst hosts.