Watson, D. 2011 用伽马暴探测银河系的金属丰度等

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Title:		The Galactic dust-to-metals ratio and metallicity using gamma-ray bursts
Authors:		Watson, D.
Affiliation:		AA(Dark Cosmology Centre, Niels Bohr Institute, University of Copenhagen, Juliane Maries Vej 30, 2100, Copenhagen Ø, Denmark darach@dark-cosmology.dk)
Publication:		Astronomy & Astrophysics, Volume 533, id.A16 (A&A Homepage)
Publication Date:		09/2011
Origin:		EDP Sciences
Astronomy Keywords:		ISM: abundances, dust, extinction, Galaxy: abundances, X-rays: ISM, gamma-ray burst: general
DOI:		10.1051/0004-6361/201117120
Bibliographic Code:		2011A&A...533A..16W

Abstract

The metallicity and dust-to-metals ratio of the Galaxy are fundamental parameters in understanding the interstellar medium (ISM). Currently, there is still some uncertainty surrounding these parameters. In this paper, the dust-to-metals ratio in the Galaxy is determined using the photoelectric absorption of the soft X-ray afterglows of a large sample of several hundred gamma-ray bursts (GRBs) to determine the metal column density in combination with Galactic dust maps to determine the line-of-sight dust extinction through the Galaxy in the direction of the GRB. GRB afterglows often have large extragalactic soft X-ray absorptions and therefore the GRB sample's upper-bound will define the Galactic dust-to-metals relation. Using a two-dimensional two-sample Kolmogorov-Smirnoff test, we determine this upper-bound and so derive the dust-to-metals ratio of the Galaxy. We find N_{H= 2.2^+0.3_{-0.4}×10²¹} cm^-2A_V as- assuming solar, Anders & Grevesse (1989, Geochim. Cosmochim. Acta, 53, 197), metallicity. This result is consistent with previous findings using bright X-ray sources in the Galaxy. Using the same technique but substituting the H i maps from the Leiden-Argentine-Bonn survey for the dust maps, allows us to place a limit on the metallicity in the Galaxy. We find a metallicity consistent with the Anders & Grevesse (1989) solar values often used in X-ray fitting. Based on this and previous studies, we suggest that the metallicity of a typical ISM sightline through the Galaxy is 0.25 dex higher than the current best estimate of the solar metallicity. We further show that the dust-to-gas ratio seems to be correlated with the total gas column density, and that this may be due to the metallicity gradient observed toward the Galactic centre. Based on the non-constant nature of the dust-to-gas ratio, we propose that the dust column density, at N_H = 2.2 × 10²¹ cm^-2 A_V, represents a better proxy for the soft X-ray absorption column density than H i maps.

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Lv, G. J. 2011 余辉的尘埃模型

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认为X射线余辉实际上尘埃散射导致的。还能解释x-ray flares

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Title:		Effect of Dust Extinction on the Gamma-ray Burst Afterglows
Authors:		Lv, G. J.; Shao, L.; Jin, Z. P.; Wei, D. M.
Publication:		Acta Astronomica Sinica, vol. 52, no. 3, p. 190-198
Publication Date:		05/2011
Origin:		ACASN
Keywords:		Gamma-ray Burst: General, Dust, Extinction
Bibliographic Code:		2011AcASn..52..190L

Abstract

In order to study the effect of dust extinction on the afterglow of gamma-ray bursts (GRBs), we carry out numerical calculations with high precision based on rigorous Mie theory and latest optical properties of interstellar dust grains, and analyze the different extinction curves produced by dust grains with different physical parameters. Our results indicate that the absolute extinction quantity is substantially determined by the medium density and metallicity, however, the shape of the extinction curve is mainly determined by the size distribution of the dust grains. If the dust grains aggregate to form larger ones, they will cause a flatter or grayer extinction curve with lower extinction quantity; on the contrary, if the dust grains are disassociated to smaller ones due to some uncertain processes, they will cause a steeper extinction curve with larger extinction quantity. These results might provide an important insight into understanding the origin of the optically dark GRBs.

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Jang, Minsung 2011 GRB 071025余辉的谱

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可以看到尘埃的特性

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Title:		Dust Properties in the Afterglow of GRB 071025 at z ~ 5
Authors:		Jang, Minsung; Im, Myungshin; Lee, Induk; Urata, Yuji; Huang, Kuiyun; Hirashita, Hiroyuki; Fan, Xiaohui; Jiang, Linhua
Affiliation:		AA(Center for the Exploration of the Origin of the Universe (CEOU), Astronomy Program, Department of Physics & Astronomy, Seoul National University, Shillim-Dong, Kwanak-Gu, Seoul 151-742, Republic of Korea msjang.astro@gmail.com), AB(Center for the Exploration of the Origin of the Universe (CEOU), Astronomy Program, Department of Physics & Astronomy, Seoul National University, Shillim-Dong, Kwanak-Gu, Seoul 151-742, Republic of Korea mim@astro.snu.ac.kr), AC(Institute of Astronomy, National Central University, Chung-Li 32054, Taiwan ), AD(Institute of Astronomy, National Central University, Chung-Li 32054, Taiwan ), AE(Institute of Astronomy and Astrophysics, Academia Sinica, P.O. Box 23-141, Taipei 10617, Taiwan ), AF(Institute of Astronomy and Astrophysics, Academia Sinica, P.O. Box 23-141, Taipei 10617, Taiwan ), AG(Steward Observatory, University of Arizona, Tucson, AZ, USA), AH(Steward Observatory, University of Arizona, Tucson, AZ, USA)
Publication:		The Astrophysical Journal Letters, Volume 741, Issue 1, article id. L20 (2011). (ApJL Homepage)
Publication Date:		11/2011
Origin:		IOP
Astronomy Keywords:		dust, extinction, galaxies: high-redshift, galaxies: ISM, gamma-ray burst: general, gamma-ray burst: individual: GRB 071025
DOI:		10.1088/2041-8205/741/1/L20
Bibliographic Code:		2011ApJ...741L..20J

Abstract

At high redshift, the universe is so young that core-collapse supernovae (SNe) are suspected to be the dominant source of dust production. However, some observations indicate that the dust production by SNe is an inefficient process, casting doubts on the existence of abundant SNe-dust in the early universe. Recently, Perley et al. reported that the afterglow of GRB 071025—an unusually red gamma-ray burst (GRB) at z ~ 5—shows evidence for SNe-produced dust. Since this is perhaps the only high-redshift GRB exhibiting compelling evidence for SNe-dust but the result could easily be affected by small systematics in photometry, we re-examined the extinction properties of GRB 071025 using our own optical/near-infrared data at a different epoch. In addition, we tested SNe-dust models with different progenitor masses and dust destruction efficiencies to constrain the dust formation mechanisms. By searching for the best-fit model of the afterglow spectral energy distribution, we confirm the previous claim that the dust in GRB 071025 is most likely to originate from SNe. We also find that the SNe-dust model of 13 or 25 M _sun without dust destruction fits the extinction property of GRB 071025 best, while pair-instability SNe models with a 170 M _sun progenitor poorly fit the data. Our results indicate that, at least in some systems at high redshift, SNe with intermediate initial masses within 10-30 M _sun were the main contributors for the dust enrichment, and the dust destruction effect due to reverse shock was negligible.

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Schady, P. 2011 伽马暴宿主星系的尘埃消光曲线

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Title:		The dust extinction curves of gamma-ray burst host galaxies
Authors:		Schady, P.; Dwelly, T.; Page, M. J.; Krühler, T.; Greiner, J.;
Affiliation:		AA(Max-Planck Institut für Extraterrestrische Physik,
Publication:		Astronomy & Astrophysics, Volume 537, id.A15 (A&A Homepage)
Publication Date:		01/2012
Origin:		EDP Sciences
Astronomy Keywords:		dust, extinction, galaxies: ISM, gamma-ray burst: general, ultraviolet: ISM
DOI:		10.1051/0004-6361/201117414
Bibliographic Code:		2012A&A...537A..15S

Abstract

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.

Appendix A is available in electronic form at http://www.aanda.org

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Krühler 2011 消光很大的几个暴的宿主星系的观测

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Title:		The SEDs and Host Galaxies of the dustiest GRB afterglows
Authors:		Krühler, T.; Greiner, J.; Schady, P.; Savaglio, S.; Afonso, P. M. J.; Clemens, C.; Elliott, J.;Filgas, R.; Gruber, D.; Kann, D. A.; Klose, S.; Küpcü-Yoldas, A.; McBreen, S.; Olivares E., F.;Pierini, D.; Rau, A.; Rossi, A.; Nardini, M.; Nicuesa Guelbenzu, A.; Sudilovsky, V.; Updike, A. C.
Publication:		eprint arXiv:1108.0674
Publication Date:		08/2011
Origin:		ARXIV
Keywords:		Astrophysics - Cosmology and Extragalactic Astrophysics
Comment:		17 pages, 13 figures, resubmitted to A&A after referee report
Bibliographic Code:		2011arXiv1108.0674K

Abstract

(Abridged) Until recently the information inferred from gamma-ray burst follow-up observations was mostly limited to optically bright afterglows, biasing all demographic studies against sight-lines that contain large amounts of dust. Here, we present GRB afterglow and host observations for a sample of bursts that are exemplary of previously missed ones because of high visual extinction along the sight-line. This facilitates an investigation of the properties, geometry and location of the absorbing dust of these poorly-explored host galaxies, and a comparison to hosts from optically-selected samples. The hosts of the dustiest afterglows are diverse in their properties, but on average redder, more luminous and massive than the hosts of optically-bright events. We hence probe a different galaxy population, suggesting that previous host samples miss most of the massive, chemically-evolved and metal-rich members. This also indicates that the dust along the sight-line is often related to host properties, and thus probably located in the diffuse ISM or interstellar clouds and not in the immediate GRB environment. Some of the hosts in our sample, are blue, young or of small stellar mass illustrating that even apparently non-extinguished galaxies possess very dusty sight-lines due to a patchy dust distribution. The presented observations establish a population of luminous, massive and correspondingly chemically-evolved GRB hosts. This suggests that GRBs trace the global star-formation rate better than studies based on optically-selected host samples indicate, and the previously-claimed deficiency of high-mass host galaxies was at least partially a selection effect.

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Stratta 2011 GRB 050904的路上尘埃

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Title:		Is GRB 050904 at z=6.3 absorbed by dust?
Authors:		Stratta, G.; Gallerani, S.; Maiolino, R.
Publication:		eprint arXiv:1106.4441
Publication Date:		06/2011
Origin:		ARXIV
Keywords:		Astrophysics - Cosmology and Extragalactic Astrophysics
Comment:		8 pages, 3 figures, accepted for publication in Astronomy and Astrophysics; figure 1 has been degraded, full resolution version at http://dl.dropbox.com/u/1670579/fig01.ps
Bibliographic Code:		2011arXiv1106.4441S

Abstract

Claim of dust extinction for this GRB has been debated in the past. We suggest that the discrepant results occur primarily because most of previous studies have not simultaneously investigated the X-ray to near-IR spectral energy distribution of this GRB. The difficulty with this burst is that the X-ray afterglow is dominated by strong flares at early times and is poorly monitored at late times. In addition, the Z band photometry, which is the most sensitive to dust extinction, has been found to be affected by strong systematics. In this paper we carefully re-analyze the Swift/XRT afterglow observations of this GRB, using extensive past studies of X-ray flare properties when computing the X-ray afterglow flux level and exploiting the recent reanalysis of the optical (UV rest frame) data of the same GRB. We extract the X-ray to optical/near-IR afterglow SED for the three epochs where the best spectral coverage is available: 0.47, 1.25, and 3.4 days after the trigger. A spectral power-law model has been fitted to the extracted SEDs. We discuss that no spectral breaks or chromatic temporal breaks are expected in the epochs of interest. To fit any UV rest-frame dust absorption, we tested the Small Magellanic Cloud (SMC) extinction curve, the mean extinction curve (MEC) found for a sample of QSO at $z>4$ and its corresponding attenuation curve, as well as a starburst attenuation curve, and the extinction curve consistent with a supernova dust origin (SN-type). The SMC extinction curve and the SN-type one provide good fit to the data at all epochs, with an average amount of dust absorption at $\lambda_{rest} = 3000 \AA$ of $A_{3000} = 0.25\pm 0.07$ mag. These results indicate that the primeval galaxy at $z = 6.3$ hosting this GRB has already enriched its ISM with dust.

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Schady 2009 宿主星系尘埃和金属的柱密度

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Title:		Dust and metal column densities in gamma-ray burst host galaxies
Authors:		Schady, P.; Page, M. J.; Oates, S. R.; Still, M.; de Pasquale, M.; Dwelly, T.; Kuin, N. P. M.; Holland, S. T.; Marshall, F. E.; Roming, P. W. A.
Affiliation:		AA(The UCL Mullard Space Science Laboratory, Holmbury St Mary, Dorking, Surrey RH5 6NT), AB(The UCL Mullard Space Science Laboratory, Holmbury St Mary, Dorking, Surrey RH5 6NT), AC(The UCL Mullard Space Science Laboratory, Holmbury St Mary, Dorking, Surrey RH5 6NT), AD(The UCL Mullard Space Science Laboratory, Holmbury St Mary, Dorking, Surrey RH5 6NT), AE(The UCL Mullard Space Science Laboratory, Holmbury St Mary, Dorking, Surrey RH5 6NT), AF(School of Physics and Astronomy, University of Southampton, Highfield, Southampton SO17 1BJ), AG(The UCL Mullard Space Science Laboratory, Holmbury St Mary, Dorking, Surrey RH5 6NT), AH(Astrophysics Science Division, Code 660.1, 8800 Greenbelt Road, GSFC, Greenbelt, MD 20771, USA; Universities Space Research Association, 10211 Wincopin Circle, Suite 500, Columbia, MD 21044, USA; CRESST, Code 668.8, 8800 Greenbelt Road, GSFC, Greenbelt, MD 20771, USA), AI(Astrophysics Science Division, Code 660.1, 8800 Greenbelt Road, GSFC, Greenbelt, MD 20771, USA), AJ(Department of Astronomy and Astrophysics, PSU, 525 Davey Laboratory, University Park, PA 16802, USA)
Publication:		Monthly Notices of the Royal Astronomical Society, Volume 401, Issue 4, pp. 2773-2792. (MNRAS Homepage)
Publication Date:		02/2010
Origin:		WILEY
MNRAS Keywords:		dust, extinction, galaxies: ISM, gamma-rays: bursts, gamma-rays: observations
DOI:		10.1111/j.1365-2966.2009.15861.x
Bibliographic Code:		2010MNRAS.401.2773S

Abstract

In this paper we present the results from the analysis of a sample of 28 gamma-ray burst (GRB) afterglow spectral energy distributions, spanning the X-ray through to near-infrared wavelengths. This is the largest sample of GRB afterglow spectral energy distributions thus far studied, providing a strong handle on the optical depth distribution of soft X-ray absorption and dust-extinction systems in GRB host galaxies. We detect an absorption system within the GRB host galaxy in 79 per cent of the sample, and an extinction system in 71 per cent of the sample, and find the Small Magellanic Cloud (SMC) extinction law to provide an acceptable fit to the host galaxy extinction profile for the majority of cases, consistent with previous findings. The range in the soft X-ray absorption to dust-extinction ratio, N_H,X/A_V, in GRB host galaxies spans almost two orders of magnitude, and the typical ratios are significantly larger than those of the Magellanic Clouds or Milky Way. Although dust destruction could be a cause, at least in part, for the large N_H,X/A_V ratios, the good fit provided by the SMC extinction law for the majority of our sample suggests that there is an abundance of small dust grains in the GRB environment, which we would expect to have been destroyed if dust destruction were responsible for the large N_H,X/A_V ratios. Instead, our analysis suggests that the distribution of N_H,X/A_V in GRB host galaxies may be mostly intrinsic to these galaxies, and this is further substantiated by evidence for a strong negative correlation between N_H,X/A_V and metallicity for a subsample of GRB hosts with known metallicity.

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Zafar 2010 GRB 050904没有尘埃消光

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Title:		No evidence for dust extinction in GRB 050904 at z ~ 6.3
Authors:		Zafar, T.; Watson, D. J.; Malesani, D.; Vreeswijk, P. M.; Fynbo, J. P. U.; Hjorth, J.; Levan, A. J.; Michałowski, M. J.
Affiliation:		AA(Dark Cosmology Centre, Niels Bohr Institute, University of Copenhagen,Juliane Maries Vej 30, 2100 Copenhagen Ø, Denmark tayyaba@dark-cosmology.dk), AB(Dark Cosmology Centre, Niels Bohr Institute, University of Copenhagen,Juliane Maries Vej 30, 2100 Copenhagen Ø, Denmark), AC(Dark Cosmology Centre, Niels Bohr Institute, University of Copenhagen,Juliane Maries Vej 30, 2100 Copenhagen Ø, Denmark), AD(Dark Cosmology Centre, Niels Bohr Institute, University of Copenhagen,Juliane Maries Vej 30, 2100 Copenhagen Ø, Denmark), AE(Dark Cosmology Centre, Niels Bohr Institute, University of Copenhagen,Juliane Maries Vej 30, 2100 Copenhagen Ø, Denmark), AF(Dark Cosmology Centre, Niels Bohr Institute, University of Copenhagen,Juliane Maries Vej 30, 2100 Copenhagen Ø, Denmark), AG(Department of Physics, University of Warwick, Coventry, CV4 7AL, UK), AH(Dark Cosmology Centre, Niels Bohr Institute, University of Copenhagen,Juliane Maries Vej 30, 2100 Copenhagen Ø, Denmark; Scottish Universities Physics Alliance, Institute for Astronomy, University of Edinburgh, Royal Observatory, Edinburgh, EH9 3HJ, UK)
Publication:		Astronomy and Astrophysics, Volume 515, id.A94 (A&A Homepage)
Publication Date:		06/2010
Origin:		EDP Sciences
Keywords:		galaxies: high-redshift, dust, extinction, gamma-ray burst: individual: GRB 050904
DOI:		10.1051/0004-6361/200913795
Bibliographic Code:		2010A&A...515A..94Z

Abstract

Context. Gamma-ray burst (GRB) afterglows are excellent and sensitive probes of gas and dust in star-forming galaxies at all epochs. It has been posited that dust in the early Universe must be different from dust at lower redshifts. To date two reports in the literature directly support this contention, one of which is based on the spectral shape of the afterglow spectrum of GRB 050904 at z = 6.295.
Aims: Here we reinvestigate the afterglow of GRB 050904 to understand cosmic dust at high redshift. We address the claimed evidence for unusual (supernova-origin) dust in its host galaxy by simultaneously examining the X-ray and optical/near-infrared spectrophotometric data of the afterglow.
Methods: We derived the intrinsic spectral energy distribution (SED) of the afterglow at three different epochs, 0.47, 1.25, and 3.4 days after the burst. We reduced again the Swift X-ray data, the 1.25 days FORS2 z-Gunn photometric data, the spectroscopic and z'-band photometric data at ~3 days from the Subaru telescope, as well as the critical UKIRT Z-band photometry at 0.47 days, upon which the claim of dust detection largely relies.
Results: We find no evidence of dust extinction in the SED at any time. We computed flux densities at λ_rest = 1250 Å directly from the observed counts at all epochs. In the earliest epoch, 0.47 days, where the claim of dust is strongest, the Z-band suppression is found to be weaker (0.3 ± 0.2 mag) than previously reported and statistically insignificant (<1.5σ). Furthermore, we find that the photometry of this band is unstable and difficult to calibrate.
Conclusions: From the afterglow SED we demonstrate that there is no evidence of dust extinction in GRB 050904 - the SED at all times can be reproduced without dust, and at 1.25 days in particular, significant extinction can be excluded, with A(3000 Å) < 0.27 mag at 95% confidence using the supernova-type extinction curve. We conclude that there is no evidence of any extinction in the afterglow of GRB 050904 and that the presence of supernova-origin dust in the host of GRB 050904 must be viewed skeptically.

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