Cold gas in the early Universe: Survey for neutral atomic-carbon in GRB host galaxies at 1 < z < 6 from optical afterglow spectroscopy

K. E. Heintz, C. Ledoux, J. P. U. Fynbo, P. Jakobsson, P. Noterdaeme, J.-K. Krogager, J. Bolmer, P. Møller, S. D. Vergani, D. Watson, T. Zafar, A. De Cia, N. R. Tanvir, D. B. Malesani, J. Japelj, S. Covino, L. Kaper

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Abstract

We present a survey for neutral atomic-carbon (C※ I) along gamma-ray burst (GRB) sightlines, which probes the shielded neutral gas-phase in the interstellar medium (ISM) of GRB host galaxies at high redshift. We compile a sample of 29 medium-to high-resolution GRB optical afterglow spectra spanning a redshift range through most of cosmic time from 1 < z < 6. We find that seven (25%) of the GRBs entering our statistical sample have C » I detected in absorption. It is evident that there is a strong excess of cold gas in GRB hosts compared to absorbers in quasar sightlines. We investigate the dust properties of the GRB C » I absorbers and find that the amount of neutral carbon is positively correlated with the visual extinction, A V , and the strength of the 2175 Å dust extinction feature, A bump . GRBs with C » I detected in absorption are all observed above a certain threshold of logN(H » I)/cm -2 + [X/H] > 20.7 and a dust-phase iron column density of logN(Fe) dust /cm -2 > 16.2. In contrast to the SED-derived dust properties, the strength of the C » I absorption does not correlate with the depletion-derived dust properties. This indicates that the GRB C » I absorbers trace dusty systems where the dust composition is dominated by carbon-rich dust grains. The observed higher metal and dust column densities of the GRB C » I absorbers compared to H2 -and C » I-bearing quasar absorbers is mainly a consequence of how the two absorber populations are selected, but is also required in the presence of intense UV radiation fields in actively star-forming galaxies.

LanguageEnglish
Article numberA20
Number of pages13
JournalAstronomy and Astrophysics
Volume621
DOIs
Publication statusPublished - 1 Jan 2019
Externally publishedYes

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cold gas
afterglows
gamma ray bursts
universe
dust
spectroscopy
galaxies
carbon
gas
absorbers
neutral gases
cold
radiation distribution
quasars
depletion
probe
vapor phases
iron
stars
probes

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Heintz, K. E. ; Ledoux, C. ; Fynbo, J. P. U. ; Jakobsson, P. ; Noterdaeme, P. ; Krogager, J.-K. ; Bolmer, J. ; Møller, P. ; Vergani, S. D. ; Watson, D. ; Zafar, T. ; De Cia, A. ; Tanvir, N. R. ; Malesani, D. B. ; Japelj, J. ; Covino, S. ; Kaper, L. / Cold gas in the early Universe : Survey for neutral atomic-carbon in GRB host galaxies at 1 < z < 6 from optical afterglow spectroscopy. In: Astronomy and Astrophysics. 2019 ; Vol. 621.
@article{f3fb0a14dccc406795c287ea88c112fe,
title = "Cold gas in the early Universe: Survey for neutral atomic-carbon in GRB host galaxies at 1 < z < 6 from optical afterglow spectroscopy",
abstract = "We present a survey for neutral atomic-carbon (C{\^a}€» I) along gamma-ray burst (GRB) sightlines, which probes the shielded neutral gas-phase in the interstellar medium (ISM) of GRB host galaxies at high redshift. We compile a sample of 29 medium-to high-resolution GRB optical afterglow spectra spanning a redshift range through most of cosmic time from 1 < z < 6. We find that seven (25{\%}) of the GRBs entering our statistical sample have C » I detected in absorption. It is evident that there is a strong excess of cold gas in GRB hosts compared to absorbers in quasar sightlines. We investigate the dust properties of the GRB C » I absorbers and find that the amount of neutral carbon is positively correlated with the visual extinction, A V , and the strength of the 2175 {\AA} dust extinction feature, A bump . GRBs with C » I detected in absorption are all observed above a certain threshold of logN(H » I)/cm -2 + [X/H] > 20.7 and a dust-phase iron column density of logN(Fe) dust /cm -2 > 16.2. In contrast to the SED-derived dust properties, the strength of the C » I absorption does not correlate with the depletion-derived dust properties. This indicates that the GRB C » I absorbers trace dusty systems where the dust composition is dominated by carbon-rich dust grains. The observed higher metal and dust column densities of the GRB C » I absorbers compared to H2 -and C » I-bearing quasar absorbers is mainly a consequence of how the two absorber populations are selected, but is also required in the presence of intense UV radiation fields in actively star-forming galaxies.",
keywords = "Dust, extinction, Galaxies: high-redshift, Galaxies: ISM, Gamma-ray burst: general",
author = "Heintz, {K. E.} and C. Ledoux and Fynbo, {J. P. U.} and P. Jakobsson and P. Noterdaeme and J.-K. Krogager and J. Bolmer and P. M{\o}ller and Vergani, {S. D.} and D. Watson and T. Zafar and {De Cia}, A. and Tanvir, {N. R.} and Malesani, {D. B.} and J. Japelj and S. Covino and L. Kaper",
year = "2019",
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Heintz, KE, Ledoux, C, Fynbo, JPU, Jakobsson, P, Noterdaeme, P, Krogager, J-K, Bolmer, J, Møller, P, Vergani, SD, Watson, D, Zafar, T, De Cia, A, Tanvir, NR, Malesani, DB, Japelj, J, Covino, S & Kaper, L 2019, 'Cold gas in the early Universe: Survey for neutral atomic-carbon in GRB host galaxies at 1 < z < 6 from optical afterglow spectroscopy' Astronomy and Astrophysics, vol. 621, A20. https://doi.org/10.1051/0004-6361/201834246

Cold gas in the early Universe : Survey for neutral atomic-carbon in GRB host galaxies at 1 < z < 6 from optical afterglow spectroscopy. / Heintz, K. E.; Ledoux, C.; Fynbo, J. P. U.; Jakobsson, P.; Noterdaeme, P.; Krogager, J.-K.; Bolmer, J.; Møller, P.; Vergani, S. D.; Watson, D.; Zafar, T.; De Cia, A.; Tanvir, N. R.; Malesani, D. B.; Japelj, J.; Covino, S.; Kaper, L.

In: Astronomy and Astrophysics, Vol. 621, A20, 01.01.2019.

Research output: Contribution to journalArticleResearchpeer-review

TY - JOUR

T1 - Cold gas in the early Universe

T2 - Astronomy and Astrophysics

AU - Heintz,K. E.

AU - Ledoux,C.

AU - Fynbo,J. P. U.

AU - Jakobsson,P.

AU - Noterdaeme,P.

AU - Krogager,J.-K.

AU - Bolmer,J.

AU - Møller,P.

AU - Vergani,S. D.

AU - Watson,D.

AU - Zafar,T.

AU - De Cia,A.

AU - Tanvir,N. R.

AU - Malesani,D. B.

AU - Japelj,J.

AU - Covino,S.

AU - Kaper,L.

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N2 - We present a survey for neutral atomic-carbon (C※ I) along gamma-ray burst (GRB) sightlines, which probes the shielded neutral gas-phase in the interstellar medium (ISM) of GRB host galaxies at high redshift. We compile a sample of 29 medium-to high-resolution GRB optical afterglow spectra spanning a redshift range through most of cosmic time from 1 < z < 6. We find that seven (25%) of the GRBs entering our statistical sample have C » I detected in absorption. It is evident that there is a strong excess of cold gas in GRB hosts compared to absorbers in quasar sightlines. We investigate the dust properties of the GRB C » I absorbers and find that the amount of neutral carbon is positively correlated with the visual extinction, A V , and the strength of the 2175 Å dust extinction feature, A bump . GRBs with C » I detected in absorption are all observed above a certain threshold of logN(H » I)/cm -2 + [X/H] > 20.7 and a dust-phase iron column density of logN(Fe) dust /cm -2 > 16.2. In contrast to the SED-derived dust properties, the strength of the C » I absorption does not correlate with the depletion-derived dust properties. This indicates that the GRB C » I absorbers trace dusty systems where the dust composition is dominated by carbon-rich dust grains. The observed higher metal and dust column densities of the GRB C » I absorbers compared to H2 -and C » I-bearing quasar absorbers is mainly a consequence of how the two absorber populations are selected, but is also required in the presence of intense UV radiation fields in actively star-forming galaxies.

AB - We present a survey for neutral atomic-carbon (C※ I) along gamma-ray burst (GRB) sightlines, which probes the shielded neutral gas-phase in the interstellar medium (ISM) of GRB host galaxies at high redshift. We compile a sample of 29 medium-to high-resolution GRB optical afterglow spectra spanning a redshift range through most of cosmic time from 1 < z < 6. We find that seven (25%) of the GRBs entering our statistical sample have C » I detected in absorption. It is evident that there is a strong excess of cold gas in GRB hosts compared to absorbers in quasar sightlines. We investigate the dust properties of the GRB C » I absorbers and find that the amount of neutral carbon is positively correlated with the visual extinction, A V , and the strength of the 2175 Å dust extinction feature, A bump . GRBs with C » I detected in absorption are all observed above a certain threshold of logN(H » I)/cm -2 + [X/H] > 20.7 and a dust-phase iron column density of logN(Fe) dust /cm -2 > 16.2. In contrast to the SED-derived dust properties, the strength of the C » I absorption does not correlate with the depletion-derived dust properties. This indicates that the GRB C » I absorbers trace dusty systems where the dust composition is dominated by carbon-rich dust grains. The observed higher metal and dust column densities of the GRB C » I absorbers compared to H2 -and C » I-bearing quasar absorbers is mainly a consequence of how the two absorber populations are selected, but is also required in the presence of intense UV radiation fields in actively star-forming galaxies.

KW - Dust, extinction

KW - Galaxies: high-redshift

KW - Galaxies: ISM

KW - Gamma-ray burst: general

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U2 - 10.1051/0004-6361/201834246

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M3 - Article

VL - 621

JO - Astronomy and Astrophysics

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SN - 0004-6361

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