Schady, P, Yates, RM, Christensen, L, De Cia, A, Rossi, A, D’Elia, V, Heintz, KE, Jakobsson, P, Laskar, T, Levan, A, Salvaterra, R, Starling, RLC, Tanvir, NR, Thöne, CC, Vergani, S, Wiersema, K, Arabsalmani, M, Chen, HW, De Pasquale, M, Fruchter, A et al, Fynbo, JPU, García-Benito, R, Gompertz, B, Hartmann, D, Kouveliotou, C, Milvang-Jensen, B, Palazzi, E, Perley, DA, Piranomonte, S, Pugliese, G, Savaglio, S, Sbarufatti, B, Schulze, S, Tagliaferri, G, de Ugarte Postigo, A, Watson, D and Wiseman, P (2024) Comparing emission- and absorption-based gas-phase metallicities in GRB host galaxies at z = 2−4 using JWST. Monthly Notices of the Royal Astronomical Society, 529 (3). pp. 2807-2831. ISSN 0035-8711

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Abstract

Much of what is known of the chemical composition of the universe is based on emission line spectra from star-forming galaxies. Emission-based inferences are, nevertheless, model-dependent and they are dominated by light from luminous star-forming regions. An alternative and sensitive probe of the metallicity of galaxies is through absorption lines imprinted on the luminous afterglow spectra of long gamma ray bursts (GRBs) from neutral material within their host galaxy. We present results from a JWST/NIRSpec programme to investigate for the first time the relation between the metallicity of neutral gas probed in absorption by GRB afterglows and the metallicity of the star-forming regions for the same host galaxy sample. Using an initial sample of eight GRB host galaxies at z = 2.1–4.7, we find a tight relation between absorption and emission line metallicities when using the recently proposed R̂ metallicity diagnostic (±0.2 dex). This agreement implies a relatively chemically homogeneous multiphase interstellar medium and indicates that absorption and emission line probes can be directly compared. However, the relation is less clear when using other diagnostics, such as R23 and R3. We also find possible evidence of an elevated N/O ratio in the host galaxy of GRB 090323 at z = 4.7, consistent with what has been seen in other z > 4 galaxies. Ultimate confirmation of an enhanced N/O ratio and of the relation between absorption and emission line metallicities will require a more direct determination of the emission line metallicity via the detection of temperature-sensitive auroral lines in our GRB host galaxy sample.

Item Type:	Article
Additional Information:	This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society ©: 2024 P. Shady et al. Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.
Uncontrolled Keywords:	0201 Astronomical and Space Sciences; Astronomy & Astrophysics
Subjects:	Q Science > QB Astronomy Q Science > QC Physics
Divisions:	Astrophysics Research Institute
Publisher:	Oxford University Press (OUP)
SWORD Depositor:	A Symplectic
Date Deposited:	16 May 2024 10:35
Last Modified:	07 Nov 2024 16:30
DOI or ID number:	10.1093/mnras/stae677
URI:	https://researchonline.ljmu.ac.uk/id/eprint/23278

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