The Nature of Grb-selected Submillimeter Galaxies: Hot and Young

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 longand 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 ∼ 150M⊙ yr ), low-mass (stellar masses ∼ 10 M⊙) and dusty (dust masses ∼ 3 × 10 M⊙). 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. Subject headings: galaxies: evolution — galaxies: high-redshift — galaxies: starburst — galaxies: ISM — dust, extinction — gamma-ray: burst