GRB 160410A : the first Chemical Study of the Interstellar Medium of a Short GRB

Fernández, J F Agüí and Thöne, C C and Kann, D A and de Ugarte Postigo, A and Selsing, J and Schady, P and Yates, R M and Greiner, J and Oates, S R and Malesani, D B and Xu, D and Klotz, A and Campana, S and Rossi, A and Perley, D A and Blažek, M and D’Avanzo, P and Giunta, A and Hartmann, D and Heintz, K E and Jakobsson, P and IV, C C Kirkpatrick and Kouveliotou, C and Melandri, A and Pugliese, G and Salvaterra, R and Starling, R L C and Tanvir, N R and Vergani, S D and Wiersema, K (2023) GRB 160410A : the first Chemical Study of the Interstellar Medium of a Short GRB. Monthly Notices of the Royal Astronomical Society, 520 (1). pp. 613-636. ISSN 0035-8711

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Abstract

Short gamma-ray bursts (SGRBs) are produced by the coalescence of compact binary systems which are remnants of massive stars. GRB 160410A is classified as a short-duration GRB with extended emission and is currently the farthest SGRB with a redshift determined from an afterglow spectrum and also one of the brightest SGRBs to date. The fast reaction to the Neil Gehrels Swift Observatory alert allowed us to obtain a spectrum of the afterglow using the X-shooter spectrograph at the Very Large Telescope (VLT). The spectrum shows several absorption features at a redshift of z = 1.7177, in addition, we detect two intervening systems at z = 1.581 and z = 1.444. The spectrum shows Lyα in absorption with a column density of log (N(HI)/cm2) = 21.2 ± 0.2 which, together with Fe ii, C ii, Si ii, Al iiand O i, allow us to perform the first study of chemical abundances in a SGRB host galaxy. We determine a metallicity of [X/H] = −2.3 ± 0.2 for Fe ii and −2.5 ± 0.2 for Si ii and no dust depletion. We also find no evidence for extinction in the afterglow Spectral Energy Distribution (SED) modeling. The environment has a low degree of ionisation and the C iv and Si iv lines are completely absent. We do not detect an underlying host galaxy down to deep limits. Additionally, we compare GRB 160410A to GRB 201221D, another high-z short GRB that shows absorption lines at z = 1.045 and an underlying massive host galaxy.