Unveiling the secrets of metallicity and massive star formation using DLAS along gamma-ray bursts

Journal Article · Fri May 01 04:00:00 EDT 2015 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/804/1/51· OSTI ID:22883242

Cucchiara, A.; Rafelski, M.; Kocevski, D. ^[1]; Fumagalli, M. ^[2]; Prochaska, J. X.; Cooke, R. J. ^[3]

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1. NASA Postdoctoral Program Fellow, Goddard Space Flight Center, Greenbelt, MD 20771 (United States)
2. Institute for Computational Cosmology, Department of Physics, Durham University, South Road, Durham, DH1 3LE (United Kingdom)
3. Department of Astronomy and Astrophysics, UCO/Lick Observatory, University of California, 1156 High Street, Santa Cruz, CA 95064 (United States)

We present the largest, publicly available sample of damped Lyα systems (DLAs) along the lines of sight of Swift-discovered gamma-ray bursts (GRBs) in order to investigate the environmental properties of long GRB hosts in the z = 1.8–6 redshift range. Compared with the most recent quasar DLA sample (QSO-DLA), our analysis shows that GRB-DLAs probe a more metal-enriched environment at z≳3, up to [X/H]∼−0.5. In the z = 2–3 redshift range, despite the large number of lower limits, there are hints that the two populations may be more similar (only at a 90% significance level) than at higher redshifts. Also, at high-z, the GRB-DLA average metallicity seems to decline at a lower rate than the QSO-DLAs: GRB-DLA hosts may be polluted with metals at least as far as ∼2 kpc from the GRB explosion site, probably due to previous star formation episodes and/or supernova explosions. This shallow metallicity trend, now extended up to z∼5, confirms previous results that GRB hosts are star-forming and have, on average, higher metallicities than the general QSO-DLA population. Finally, our host metallicity measurements are broadly consistent with the predictions derived from the hypothesis of two channels of GRB progenitors, one of which is mildly affected by a metallicity bias, although more data are needed to constrain the models at z≳4.

• OSTI ID: 22883242
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 1 Vol. 804; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United Kingdom
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
ABSORPTION
COMPARATIVE EVALUATIONS
COSMIC GAMMA BURSTS
EXPLOSIONS
FORECASTING
GALAXIES
METALLICITY
QUASARS
RED SHIFT
SPECTROSCOPY
STARS