Galactic Archaeology at High Redshift: Inferring the Nature of GRB Host Galaxies from Abundances

Abstract

We identify the nature of high redshift long Gamma-Ray Bursts (LGRBs) host galaxies by comparing the observed abundance ratios in the interstellar medium with detailed chemical evolution models accounting for the presence of dust. We compare abundance data from long Gamma-Ray Bursts afterglow spectra to abundance patterns as predicted by our models for different galaxy types. We analyse [X/F e] abundance ratios (where X is C, N , O, M g, Si, S, N i, Zn) as functions of [F e/H]. Different galaxies (irregulars, spirals, spheroids) are, in fact, characterised by different star formation histories, which produce different [X/F e] vs. [F e/H] relations ("time-delay model"). This allows us to identify the star formation history of the host galaxies and to infer their age (i.e. the time elapsed from the beginning of star formation) at the time of the GRB events. Unlike previous works, we use newer models in which we adopt updated stellar yields and prescriptions for dust production, accretion and destruction. We consider a sample of seven LGRB host galaxies. Our results suggest that two of them (GRB 050820, GRB 120815A) are star forming spheroids, two (GRB 081008, GRB 161023A) are spirals and three (GRB 090926A, GRB 050730, GRB 120327A) are irregulars. The inferred ages of the considered host galaxies span from 10 M yr to slightly more than 1 Gyr.

[Mg/Fe] ratios in the solar neighbourhood: stellar yields and chemical evolution scenarios

“…where the disc scale length R d is 3.5 kpc for the low-α disc (e.g. Spitoni et al 2017) and 2.3 kpc for the high-α disc (Pouliasis et al 2017, see also Palla et al 2020a). This leads to a Σ low /Σ high increasing with radius in agreement with recent observational and theoretical works (e.g.…”

“…This parameter is set to 2 Gyr −1 for the first infall/high-α star formation episode and to 1 Gyr −1 for the second infall/low-α episode. R i (R, t) (see Palla et al 2020a for the complete expression) takes into account the nucleosynthesis from low-intermediate mass stars (LIMS, m < 8 M ), core collapse (CC) SNe (Type II and Ib/c, m > 8 M ) and Type Ia SNe (SN Ia). For these latter, we assume the single-degenerate (SD) scenario and in particular the delay-time-distribution (DTD) by Matteucci & Recchi (2001).…”

Chemical evolution of the Milky Way: constraints on the formation of the thick and thin discs

“…where gas is the surface gas density, k = 1.5 is the law index, and ν is the SFE. R i (R, t) (see Palla et al 2020 for the complete expression) takes into account the nucleosynthesis from low-intermediate mass stars (LIMS, m < 8M ), core collapse (CC) SNe (Type II and Ib/c, m > 8M ), and Type Ia SNe. For these latter, we assume the single-degenerate (SD) scenario, in which a C-O white dwarf in a binary system accretes mass from a non-degenerate companion until it reaches nearly the Chandrasekhar mass (∼1.44M ).…”

Chemical evolution of the Milky Way: constraints on the formation of the thick and thin discs

“…where Σ gas is the surface gas density, k = 1.5 is the law index and ν is the star formation efficiency. R i (R, t) (see Palla et al 2020 for the complete expression) takes into account the nucleosynthesis from lowintermediate mass stars (LIMS, m < 8M ), core collapse (CC) SNe (Type II and Ib/c, m > 8M ) and Type Ia SNe. For these latter, we assume the single-degenerate (SD) scenario, in which a C-O white dwarf in a binary system accretes mass from a non-degenerate companion until it reaches nearly the Chandrasekhar mass (∼ 1.44M ).…”