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Rapid Response Mode observations of GRB 160203A: Looking for fine-structure line variability at z = 3.52

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posted on 2024-10-30, 10:10 authored by G Pugliese, A Saccardi, V D’Elia, SD Vergani, KE Heintz, S Savaglio, L Kaper, A de Ugarte Postigo, DH Hartmann, A De Cia, S Vejlgaard, JPU Fynbo, L Christensen, S Campana, D van Rest, J Selsing, K Wiersema, DB Malesani, S Covino, D Burgarella, M De Pasquale, P Jakobsson, J Japelj, DA Kann, C Kouveliotou, A Rossi, NR Tanvir, CC Thöne, D Xu

Context. 

Gamma-ray bursts are the most energetic known explosions. Although they fade rapidly, they give us the opportunity to measure redshift and important properties of their host galaxies. We report the photometric and spectroscopic study of the Swift GRB 160203A at z = 3.518, and its host galaxy. Fine-structure absorption lines, detected in the afterglow at different epochs, allow us to investigate variability due to the strong fading background source. 


Aims. 

We obtained two optical to near-infrared spectra of the GRB afterglow with X-shooter on ESO/VLT, 18 minutes and 5.7 hours after the burst, allowing us to investigate temporal changes of fine-structure absorption lines. 


Methods. 

We measured H I column density log N(HI/cm–2) = 21.75 ± 0.10, and several heavy-element ions along the GRB sightline in the host galaxy, among which Si II, Al II, Al III, C II, Ni II, Si IV, C IV, Zn II and Fe II, and Fe II∗ and Si II∗ fine-structure transitions from energetic levels excited by the afterglow, at the common redshift z = 3.518. We measured [M/H]TOT = –0.78 ± 0.13 and a [Zn/Fe]FIT = 0.69 ± 0.15, representing the total (dust corrected) metallicity and dust depletion, respectively. We detected additional intervening systems along the line of sight at ɀ = 1.03, ɀ = 1.26, ɀ = 1.98, ɀ = 1.99, ɀ = 2.20, and ɀ = 2.83. We could not measure significant variability in the strength of the fine-structure lines throughout all the observations and determined an upper limit for the GRB distance from the absorber of d < 300 pc, adopting the canonical UV pumping scenario. However, we note that the quality of our data is not sufficient to conclusively rule out collisions as an alternative mechanism. 


Results. 

GRB 160203A belongs to a growing sample of GRBs with medium resolution spectroscopy, provided by the Swift/X-shooter legacy programme, which enables a detailed investigation of the interstellar medium in high-redshift GRB host galaxies. In particular, this host galaxy shows relatively high metal enrichment and dust depletion already in place when the universe was only 1.8 Gyr old.

Funding

Carlsberg Foundation Reintegration Fellowship Grant CF21-0103

Interstellar one: one vision for the Interstellar Medium at all cosmic times

Swiss National Science Foundation

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Spanish National Research Project RTI2018-098104-J-I00 (GRBPhot)

Transient Engine Driven Explosions

European Research Council

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History

Citation

Rapid Response Mode observations of GRB 160203A: Looking for fine-structure line variability at z = 3.52 G. Pugliese, A. Saccardi, V. D’Elia, S. D. Vergani, K. E. Heintz, S. Savaglio, L. Kaper, A. de Ugarte Postigo, D. H. Hartmann, A. De Cia, S. Vejlgaard, J. P. U. Fynbo, L. Christensen, S. Campana, D. van Rest, J. Selsing, K. Wiersema, D. B. Malesani, S. Covino, D. Burgarella, M. De Pasquale, P. Jakobsson, J. Japelj, D. A. Kann, C. Kouveliotou, A. Rossi, N. R. Tanvir, C. C. Thöne and D. Xu A&A, 690 (2024) A35

Author affiliation

College of Science & Engineering/Physics & Astronomy

Version

  • VoR (Version of Record)

Published in

Astronomy & Astrophysics

Volume

690

Pagination

A35 - A35

Publisher

EDP Sciences

issn

0004-6361

eissn

1432-0746

Acceptance date

2024-06-24

Copyright date

2024

Available date

2024-10-30

Language

en

Deposited by

Professor Nial Tanvir

Deposit date

2024-10-24

Rights Retention Statement

  • No

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