A log <i>N</i><sub>H <scp>i</scp></sub>= 22.6 Damped Lyα Absorber in a Dark Gamma‐Ray Burst: The Environment of GRB 050401

Watson, Derrick G.; Fynbo, J. P. U.; Ledoux, C.; Vreeswijk, P. M.; Hjorth, J.; Smette, A.; Andersen, Anja C.; Aoki, Kentaro; Augusteijn, T.; Beardmore, A. P.; Bersier, D.; Cerón, J. M. Castro; D’Avanzo, P.; Díaz-Fraile, D.; Gorosabel, J.; Hirst, Paul; Jakobsson, P.; Jensen, B. L.; Kawai, N.; Kosugi, George; Laursen, Peter; Levan, A. J.; Masegosa, J.; Näränen, Jyri; Page, K. L.; Pedersen, K.; Pozanenko, A.; Reeves, J. N.; Rumyantsev, V.; Shahbaz, T.; Sharapov, D.; Sollerman, J.; Starling, R.; Tanvir, N. R.; Torstensson, K.; Wiersema, K.

doi:10.1086/508049

Cited by 117 publications

(99 citation statements)

References 60 publications

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“…Moreover, hints at the presence of H 2 and/or C i lines have been reported at the host-galaxy redshifts of GRB 050401 (Watson et al 2006), GRB 060206 , and GRB 070802 (Elíasdóttir et al 2009), while the metallicities of these hosts are amongst the highest measured in GRB-DLAs. This suggests that it is only a matter of time before H 2 and/or other molecules are detected beyond any doubt in GRB-DLAs 6 .…”

Section: Summary and Prospectsmentioning

confidence: 93%

“…At the GRB host-galaxy redshift, large amounts of neutral, singly, and highly ionized gas are usually seen (e.g., Fiore et al 2005;Prochaska et al 2007b;Fox et al 2008), including the highest neutral hydrogen column densities measured to date at high redshift from UV absorption-line spectroscopy (e.g., Vreeswijk et al 2004;Chen et al 2005;Berger et al 2006). While such high H 0 column densities suggest an origin in the immediate surroundings of the GRB and/or the inner regions of its host, the overall H 0 column density distribution of the absorbers is fairly flat (Jakobsson et al 2006), with values as low as ≈10 17 up to 10 22.6 atoms cm −2 Watson et al 2006), illustrating the diversity of environments probed by the observations. Metallicities measured in the H 0 gas vary widely from less than 1/100th of solar to nearly solar -with a tendency for low metallicities - Prochaska et al 2007b), consistent with an origin in dwarf and/or low-mass galaxies and the currently favoured scenario for long-duration Article published by EDP Sciences GRBs, the collapse of a massive Wolf-Rayet star endowed with rotation (Woosley 1993;MacFadyen & Woosley 1999;Woosley & Heger 2004).…”

Section: Introductionmentioning

confidence: 96%

“…Searches for molecular hydrogen in GRB-DLAs, thus equivalently in the interstellar medium (ISM) of GRB host galaxies, have led to negative results till now, though in two cases, towards GRB 050401 and GRB 060206, tentative evidence of H 2 lines has been reported (Watson et al 2006;Fynbo et al 2006). The H 2 column-density upper limits derived in a handful of cases from the non-detection of UV absorption lines are somewhat surprising given the very high H 0 column densities observed in some GRB-DLAs.…”

Section: Introductionmentioning

confidence: 99%

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Physical conditions in high-redshift GRB-DLA absorbers observed with VLT/UVES: implications for molecular hydrogen searches

Ledoux¹,

Vreeswijk

Smette³

et al. 2009

A&A

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160

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Aims. We aim to understand the nature of the absorbing neutral gas in the galaxies hosting high-redshift long-duration gamma-ray bursts (GRBs) and to determine their physical conditions. Methods. A detailed analysis of high-quality VLT/UVES spectra of the optical afterglow of GRB 050730 and other Swift-era bursts is presented. Results. We report the detection of a significant number of previously unidentified allowed transition lines of Fe + , involving the fine structure of the ground term ( 6 D 7/2 , 6 D 5/2 , 6 D 3/2 , 6 D 1/2 ) and that of other excited levels ( 4 F 9/2 , 4 F 7/2 , 4 F 5/2 , 4 F 3/2 , 4 D 7/2 , 4 D 5/2 ), from the z abs = 3.969, log N(H 0 ) = 22.10, damped Lyman-α (DLA) system located in the host galaxy of GRB 050730. No molecular hydrogen (H 2 ) is detected down to a molecular fraction of log f < −8.0. We derive accurate metal abundances for Fe + , S + , N 0 , Ni + , and, for the first time in this system, Si + and Ar 0 . The absorption lines are best-fit as a single narrow velocity component at z abs = 3.96857. The time-dependent evolution of the observed Fe + energy-level populations is modelled by assuming the excitation mechanism is fluorescence following excitation by ultraviolet photons emitted by the afterglow of GRB 050730. This UV pumping model successfully reproduces the observations, yielding a total Fe + column density of log N = 15.49 ± 0.03, a burst/cloud distance (defined to the near-side of the cloud) of d = 440 ± 30 pc, and a linear cloud size of l = 520 +240 −190 pc. This application of our photoexcitation code demonstrates that burst/DLA distances can be determined without strong constraints on absorption-line variability provided enough energy levels are detected. From the cloud size, we infer a particle density of n H ≈ 5−15 cm −3 . Conclusions.We discuss these results in the context of no detections of H 2 and C i lines (with log N(C 0 )/N(S + ) < −3) in a sample of seven z > 1.8 GRB host galaxies observed with VLT/UVES. We show that the lack of H 2 can be explained by the low metallicities, [X/H] < −1, low depletion factors, and, at most, moderate particle densities of the systems. This points to a picture where GRB-DLAs typically exhibiting very high H 0 column densities are diffuse metal-poor atomic clouds with high kinetic temperatures, T kin > ∼ 1000 K, and large physical extents, l > ∼ 100 pc. The properties of GRB-DLAs observed at high spectral resolution towards bright GRB afterglows differ markedly from the high metal and dust contents of GRB-DLAs observed at lower resolution. This difference likely results from the effect of a bias, against systems of high metallicity and/or close to the GRB, due to dust obscuration in the magnitudelimited GRB afterglow samples observed with high-resolution spectrographs.

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Section: Summary and Prospectsmentioning

confidence: 93%

Section: Introductionmentioning

confidence: 96%

Section: Introductionmentioning

confidence: 99%

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Physical conditions in high-redshift GRB-DLA absorbers observed with VLT/UVES: implications for molecular hydrogen searches

Ledoux¹,

Vreeswijk

Smette³

et al. 2009

A&A

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160

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“…Webster et al 1995;Pei et al 1991;Murphy & Liske 2004;Maiolino et al 2004;Ellison et al 2005;Vladilo et al 2006;Gallerani et al 2010) or gamma-ray bursts (GRBs; e.g. Galama & Wijers 2001;Savaglio et al 2003;Stratta et al 2004;Kann et al 2006;Starling et al 2007;Watson et al 2006;Schady et al 2007).…”

Section: Introductionmentioning

confidence: 99%

The dust extinction curves of gamma-ray burst host galaxies

Schady¹,

Dwelly²,

Page³

et al. 2011

A&A

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The composition and amount of interstellar dust within gamma-ray burst (GRB) host galaxies is of key importance when addressing selection effects in the GRB redshift distribution, and when studying the properties of their host galaxies. As well as the implications for GRB research, probing the dust within the high-z hosts of GRBs also contributes to our understanding of the conditions of the interstellar medium and star-formation in the distant Universe. Nevertheless, the physical properties of dust within GRB host galaxies continues to be a highly contended issue. In this paper we explore the mean extinction properties of dust within the host galaxies of a sample of 17 GRBs with total host galaxy visual extinction A V < 1 ( A V = 0.4), covering a redshift range z = 0.7−3.1. We find the average host extinction curve to have an ultraviolet slope comparable to that of the LMC, but with little evidence of a 2175 Å dust extinction feature as observed along Milky Way and LMC sightlines. We cannot at present rule out the presence of a 2175 Å feature, and both the standard SMC and LMC extinction curves also provide good fits to our data. However, we can reject an extinction curve that has a UV slope as flat as the mean Milky Way extinction curve, whilst also having a 2175 Å feature as prominent as seen in the mean Milky Way extinction curve. This is in contrast to the clear detection of a 2175 Å bump and the flatter extinction curves of some more heavily extinguished GRBs (A V > 1), which may be indicative of there being a dependence between dust abundance and the wavelength dependence of dust extinction, as has been previously speculated.

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“…While in the past samples were biased towards low extinction bursts, showing typical intrinsic reddening to be well below A V ∼ 0.5 mag (Kann et al 2006), recent observations provide evidence of highly reddened afterglows (Watson et al 2006;Rol et al 2007;Krühler et al 2008;Elíasdóttir et al 2009;Prochaska et al 2009). The case of GRB 070306, detected initially in the K-band, is a remarkable example of a highly reddened burst with z = 1.496 and suggested A V = 5.6 mag (Jaunsen et al 2008).…”

Section: Photometric Redshiftmentioning

confidence: 94%

GRB 050502B optical afterglow: a jet-break at high redshift

Afonso

Greiner

Pian

et al. 2011

A&A

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Aims. Swift GRB 050502B is well known for the very bright flare displayed in its X-ray light curve. Despite extensive studies, however, the optical light curve has never been discussed and its redshift is unconstrained. Possible correlations between optical and X-ray data are analysed. Methods. Photometric data from TNG in the R and I bands were used to compare the optical afterglow with the X-ray light curve. The HyperZ package and a late-time VLT host observation were used to derive redshift estimates. Results. The I-band afterglow decay followed a power law of index α = 2.1 ± 0.6, after a late break at ∼1.3 × 10 5 s. The R − I colour is remarkably red and the broadband spectral index β OX = 0.9±0.1 is consistent with the X-ray spectral slope β X . Although a photometric redshift of z > 4 is the most conservative result to consider, a photometric redshift of z = 5.2 ± 0.3 is suggested with no extinction in the host, based on which an isotropic energy E γ,iso = (3.8 ± 0.7) × 10 52 erg and a jet opening angle θ ∼ 3.7 • are subsequently derived. Conclusions. The combined X-ray and optical data suggest an achromatic break, which we interpret as a jet-break. The post jet-break slope roughly obeys the closure relation for the jet's slow cooling model. Because of the afterglow's very red colour, in order for the redshift to be low (z < 1), extinction must be significantly high if present in the host. Since the optical-to-X-ray index is consistent with the X-ray spectrum, and there is no XRT evidence for excess N H , GRB 050502B was likely at high redshift.

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A log N_H i= 22.6 Damped Lyα Absorber in a Dark Gamma‐Ray Burst: The Environment of GRB 050401

Cited by 117 publications

References 60 publications

Physical conditions in high-redshift GRB-DLA absorbers observed with VLT/UVES: implications for molecular hydrogen searches

Physical conditions in high-redshift GRB-DLA absorbers observed with VLT/UVES: implications for molecular hydrogen searches

The dust extinction curves of gamma-ray burst host galaxies

GRB 050502B optical afterglow: a jet-break at high redshift

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A log NH i= 22.6 Damped Lyα Absorber in a Dark Gamma‐Ray Burst: The Environment of GRB 050401

Cited by 117 publications

References 60 publications

Physical conditions in high-redshift GRB-DLA absorbers observed with VLT/UVES: implications for molecular hydrogen searches

Physical conditions in high-redshift GRB-DLA absorbers observed with VLT/UVES: implications for molecular hydrogen searches

The dust extinction curves of gamma-ray burst host galaxies

GRB 050502B optical afterglow: a jet-break at high redshift

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A log N_H i= 22.6 Damped Lyα Absorber in a Dark Gamma‐Ray Burst: The Environment of GRB 050401