The nature of GRB-selected submillimeter galaxies: hot and young

TL;DR

This study analyzes four GRB-selected submillimeter galaxies, revealing they are young, hot, dusty, and highly star-forming, differing from typical submm galaxies by being less massive and hotter.

Contribution

It provides detailed spectral energy distribution fits showing that GRB-selected submm galaxies are younger, hotter, and less massive than previously known submm galaxies.

Findings

Galaxies are young (<2 Gyr) and highly star-forming (~150 MSun/yr)

They are hotter (Td>45 K) and less massive (~10^10 MSun)

GRB hosts differ from typical submm galaxies by being hotter and younger.

Abstract

We present detailed fits of the spectral energy distributions (SEDs) of four submillimeter (submm) galaxies selected by the presence of a gamma-ray burst (GRB) event (GRBs 980703, 000210, 000418 and 010222). These faint ~3 mJy submm emitters at redshift ~1 are characterized by an unusual combination of long- and short-wavelength properties, namely enhanced submm and/or radio emission combined with optical faintness and blue colors. We exclude an active galactic nucleus as the source of long-wavelength emission. From the SED fits we conclude that the four galaxies are young (ages <2 Gyr), highly starforming (star formation rates ~150 MSun/yr), low-mass (stellar masses ~10^10 MSun) and dusty (dust masses ~3x10^8 MSun). Their high dust temperatures (Td>45 K) indicate that GRB host galaxies are hotter, younger, and less massive counterparts to submm-selected galaxies detected so far. Future facilities like Herschel, JCMT/SCUBA-2 and ALMA will test this hypothesis enabling measurement of dust temperatures of fainter GRB-selected galaxies.