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Are long gamma-ray bursts biased tracers of star formation? Clues from the host galaxies of the Swift/BAT6 complete sample of bright LGRBs II. Star formation rates and metallicities at z < 1



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Gallego Maestro, Jesús and otros, ... (2016) Are long gamma-ray bursts biased tracers of star formation? Clues from the host galaxies of the Swift/BAT6 complete sample of bright LGRBs II. Star formation rates and metallicities at z < 1. Astronomy & Astrophysics, 590 . ISSN 1432-0746

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Official URL: http://dx.doi.org/10.1051/0004-6361/201628314


Aims. Long gamma-ray bursts (LGRBs) are associated with the deaths of massive stars and might therefore be a potentially powerful tool for tracing cosmic star formation. However, especially at low redshifts (z< 1.5) LGRBs seem to prefer particular types of environment. Our aim is to study the host galaxies of a complete sample of bright LGRBs to investigate the effect of the environment on GRB formation.
Methods. We studied host galaxy spectra of the Swift/BAT6 complete sample of 14 z< 1 bright LGRBs. We used the detected nebular emission lines to measure the dust extinction, star formation rate (SFR), and nebular metallicity (Z) of the hosts and supplemented the data set with previously measured stellar masses M_*. The distributions of the obtained properties and their interrelations (e.g. mass-metallicity and SFR-M_* relations) are compared to samples of field star-forming galaxies.
Results. We find that LGRB hosts at z< 1 have on average lower SFRs than if they were direct star formation tracers. By directly comparing metallicity distributions of LGRB hosts and star-forming galaxies, we find a good match between the two populations up to 12 +log (O/H)~8.4−8.5, after which the paucity of metal-rich LGRB hosts becomes apparent. The LGRB host galaxies of our complete sample are consistent with the mass-metallicity relation at similar mean redshift and stellar masses. The cutoff against high metallicities (and high masses) can explain the low SFR values of LGRB hosts. We find a hint of an increased incidence of starburst galaxies in the Swift/BAT6 z< 1 sample with respect to that of a field star-forming population. Given that the SFRs are low on average, the latter is ascribed to low stellar masses. Nevertheless, the limits on the completeness and metallicity availability of current surveys, coupled with the limited number of LGRB host galaxies, prevents us from investigating more quantitatively whether the starburst incidence is such as expected after taking into account the high-metallicity aversion of LGRB host galaxies.

Item Type:Article
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© ESO 2016.
Artículo firmado por 24 autores.
We thank the referee for the helpful comments that improved the paper. S.D.V. thanks C. Belczynski, C.Georgy, J. Groh, O. Le Fevre, L. Kewley and L. Tasca for fruitful discussions. J.J. and S.C. acknowledge financial contribution from the grant PRIN MIUR 2012 201278X4FL 002 The Intergalactic Medium as a probe of the growth of cosmic structures. S.D.V. and E.L.F. acknowledge the UnivEarthS Labex programme at Sorbonne Paris Cite (ANR-10-LABX-0023 and ANR-11-IDEX-0005-02). A.F.S. acknowledges support from grants AYA2013-48623-C2-2 from the Spanish Ministerio de Economía y Competitividad, and PrometeoII 2014/060 from the Generalitat Valenciana. This research uses data from the VIMOS VLT Deep Survey, obtained from the VVDS database operated by Cesam, Laboratoire d'Astrophysique de Marseille, France. This work is partly based on observations made with the Gran Telescopio Canarias (GTC), installed in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofísica de Canarias in the island of La Palma.

Uncontrolled Keywords:Core-collapse supernovae; High-redshift galaxies; Hubble-space-telescope; Digital sky survey; Less-than 2.5; Mass-metallicity; Forming galaxies; Luminosity function; Stellar mass; X-shooter
Subjects:Sciences > Physics > Astrophysics
Sciences > Physics > Astronomy
ID Code:38731
Deposited On:05 Aug 2016 13:23
Last Modified:10 Dec 2018 15:04

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