2011/03/31 by Yuu Niino, Y. Niino · 2 citations
Engineering · Physics and Astronomy · #Astronomy and Astrophysical Research #Bimodality #CCD and CMOS Imaging Sensors #Galaxy #Galaxy formation and evolution #Gamma-ray burst #Gamma-ray bursts and supernovae #Metallicity #Milky Way #Redshift #Star formation #astro-ph.CO
paper · pdf · doi:10.1111/j.1365-2966.2011.19299.x
6 pages, 5 figures, accepted for publication in MNRAS
arxiv created 2011/07/07 · openalex publication_date 2011/09/09 · arxiv updated 2015/05/27 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
We predict the metallicity probability distribution function (PDF) of long gamma-ray burst (GRB) host galaxies at low redshifts (z≲ 0.3) when GRBs occur only in low-metallicity environments, assuming empirical formulations of galaxy properties. We discuss the contribution of high-metallicity galaxies to the cosmic rate of low-metallicity GRBs, taking the internal dispersion of metallicity within each galaxy into account. Assuming that GRBs trace low-metallicity star formation <Zcrit: 12+log10(O/H) = 8.2, we find that GRB host galaxies may have systematically higher metallicity than GRB progenitors. Furthermore, we expect >rsim10 per cent of the host galaxies to have 12+log10(O/H) > 8.8, if galaxies have an internal dispersion of metallicity comparable to that observed in the Milky Way. Our results show that the low-metallicity scenario of GRB progenitors can be reconciled with recent discoveries of the high-metallicity host galaxies of GRBs. We also show a possible bimodality in the host metallicity PDF that results from the single-progenitor model of GRBs. If found in future observations, the bimodality might be a clue to constrain the nature of GRB progenitors.