Gas inflow and outflow in an interacting high-redshift galaxy. The remarkable host environment of GRB 080810 at z = 3.35

P. Wiseman, D.~A. Perley, P. Schady, J.~X. Prochaska, A. de Ugarte Postigo, T. Krühler, R.~M. Yates, J. Greiner

Research output: Contribution to journalArticlepeer-review

10 Citations (Scopus)

Abstract

We reveal multiple components of an interacting galaxy system at z ≈ 3.35 through a detailed analysis of the exquisite high-resolution Keck/HIRES spectrum of the afterglow of a gamma-ray burst (GRB). Through Voigt-profile fitting of absorption lines from the Lyman series, we constrain the neutral hydrogen column density to NH i ≤ 1018.35 cm-2 for the densest of four distinct systems at the host redshift of GRB 080810, which is among the lowest NH i ever observed in a GRB host, even though the line of sight passes within a projected 5 kpc of the galaxy centres. By detailed analysis of the corresponding metal absorption lines, we derive chemical, ionic, and kinematic properties of the individual absorbing systems, and thus build a picture of the host as a whole. Striking differences between the systems imply that the line of sight passes through several phases of gas: the star-forming regions of the GRB host; enriched material in the form of a galactic outflow; the hot and ionised halo of a second interacting galaxy falling towards the host at a line-of-sight velocity of 700 km s-1; and a cool metal-poor cloud that may represent one of the best candidates yet for the inflow of metal-poor gas from the intergalactic medium.
Original languageEnglish
Article numberA107
Number of pages18
JournalAstronomy & Astrophysics
Volume607
Early online date22 Nov 2017
DOIs
Publication statusE-pub ahead of print - 22 Nov 2017

Keywords

  • galaxies: evolution, galaxies: interactions, gamma-ray burst: individual: 080810, Astrophysics - Astrophysics of Galaxies

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