2006/09/07 by E. Berger, D. B. Fox, S. R. Kulkarni +2 · 1 citation
Physics and Astronomy · #Astrophysical Phenomena and Observations #Gamma-ray bursts and supernovae #Stellar, planetary, and galactic studies #astro-ph
paper · pdf · doi:10.1086/513007
published as Astrophys.J.660:504-508,2007 · Submitted to ApJ; 9 pages, 4 figures
arxiv created 2006/09/07 · openalex publication_date 2007/04/20 · arxiv updated 2010/05/12 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/01
We present optical and near-IR observations of the host galaxy of GRB 020127, for which we measure R - K s = 6.2 mag. This is only the second GRB host to date classified as an ERO. The spectral energy distribution (SED) is typical of a dusty starburst galaxy, with a redshift z ≈ 1.9, a luminosity L ≈ 5 L *, and an inferred stellar mass of M * ~ 10 11 -10 12 M ☉ , two orders of magnitude more massive than typical GRB hosts. A comparison to the z ~ 2 mass-metallicity ( M - Z ) relation suggests that the host metallicity is about 0.5-1 Z ☉ . This result shows that at least some GRBs occur in massive, metal-enriched galaxies, and that the proposed low-metallicity bias of GRB progenitors is not as severe as previously claimed. Instead, we propose that the blue colors and sub- L * luminosities of most GRB hosts reflect their young starburst populations. This explanation also accounts for the prevalence of low-redshift GRBs in low-mass galaxies, since star formation activity shifts from high- to low-mass galaxies as a function of decreasing redshift ("downsizing"). Thus, the low-metallicity bias claimed for z ≲ 0.2 GRB hosts is likely a secondary effect, which reflects the M - Z relation, and consequently GRBs and their hosts may serve as a reliable tracer of cosmic star formation activity.