Patel, M. 2010 利用GRB 080913来分析星系际物质的电离率

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Title:		The reanalysis of spectra of GRB 080913 to estimate the neutral fraction of the IGM at a redshift of 6.7
Authors:		Patel, M.; Warren, S. J.; Mortlock, D. J.; Fynbo, J. P. U.
Affiliation:		AA(Astrophysics Group, Imperial College London, Blackett Laboratory, Prince Consort Road, London, SW7 2AZ, UK m.patel06@imperial.ac.uk), AB(Astrophysics Group, Imperial College London, Blackett Laboratory, Prince Consort Road, London, SW7 2AZ, UK), AC(Astrophysics Group, Imperial College London, Blackett Laboratory, Prince Consort Road, London, SW7 2AZ, UK), AD(Dark Cosmology Centre, Niels Bohr Institute, University of Copenhagen, Juliane Maries Vej 30, 21000 Copenhagen, Denmark)
Publication:		Astronomy and Astrophysics, Volume 512, id.L3 (A&A Homepage)
Publication Date:		03/2010
Origin:		EDP Sciences
Keywords:		dark ages, reionization, first stars, gamma-ray burst: individual: GRB 080913, techniques: spectroscopic
DOI:		10.1051/0004-6361/200913876
Bibliographic Code:		2010A&A...512L...3P

Abstract

Aims: We reanalyse optical spectra of the z=6.7 gamma-ray burst GRB 080913, adding hitherto unpublished spectra, to reassess the measurement of the neutral fraction of the IGM at high redshifts.
Methods: In the data reduction, we take particular care to minimise systematic errors in the sky subtraction, which are evident in the published spectrum, and compromise our analysis. The final combined spectrum has a higher signal-to-noise ration (S/N) than the previously published spectrum by a factor of 1.3.
Results: We find a single significant absorption line redward of the Lyα continuum break, which we identify with the ii + Siii λ 0.126 μm blend, at z=6.733. The sharp spectral break at Lyα implies a comparatively low total column density of neutral hydrogen along the line of sight, log({N_HI}/cm^-2)<20. We model the absorption with a host-galaxy DLA, surrounded by an ionised region of unknown size r, within the IGM of neutral fraction, x_HI. Despite knowing the source redshift, and the improved S/N of the spectrum, when fitting only over wavelengths redward of Lyα, no useful constraints on x_HI can be obtained. We consider the possibility of including the ionised region, blueward of Lyα, when constraining the fit. For the optimistic assumption that the ionised region is transparent, τ_GP≪1, we find that the region is of small size r<2 proper Mpc, and we obtain an upper limit to the neutral fraction of the IGM at z=6.7 of x_HI<0.73 at a probability of 90%.

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Deng 2010 拟合余辉得到GRB 030329的喷流张角

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Title:		Measuring the beaming angle of GRB 030329 by fitting the rebrightenings in its multiband afterglow
Authors:		Deng, Wei; Huang, Yong-Feng; Kong, Si-Wei
Publication:		eprint arXiv:1003.0099
Publication Date:		02/2010
Origin:		ARXIV
Keywords:		Astrophysics - High Energy Astrophysical Phenomena
Comment:		8 pages, 6 figures, Has been accepted by RAA (Research in Astronomy and Astrophysics)
Bibliographic Code:		2010arXiv1003.0099D

Abstract

Multiple rebrightenings have been observed in the multiband afterglow of GRB 030329. Especially, a marked and quick rebrightening occurred at about t ~ 1.2 * 10^5 s. Energy injection from late and slow shells seems to be the best interpretation for these rebrightenings. Usually it is assumed that the energy is injected into the whole external shock. However, in the case of GRB 030329, the rebrightenings are so quick that the usual consideration fails to give a satisfactory fit to the observed light curves. Actually, since these late/slow shells coast freely in the wake of the external shock, they should be cold and may not expand laterally. The energy injection then should only occur at the central region of the external shock. Considering this effect, we numerically re-fit the quick rebrightenings observed in GRB 030329. By doing this, we were able to derive the beaming angle of the energy injection process. Our result, with a relative residual of only 5% - 10% during the major rebrightening, is better than any previous modeling. The derived energy injection angle is about 0.035. We assume that these late shells are ejected by the central engine via the same mechanism as those early shells that produce the prompt gamma-ray burst. The main difference is that their velocities are much slower, so that they catch up with the external shock very lately and manifest as the observed quick rebrightenings. If this were true, then the derived energy injection angle can give a good measure of the beaming angle of the prompt gamma-ray emission. Our study may hopefully provide a novel method to measure the beaming angle of gamma-ray bursts.

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Calvez 2010 超高能宇宙射线的正电子超可能来自银河系以前的伽马暴

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Title:		Can past gamma-ray bursts explain both INTEGRAL and ATIC/PAMELA/Fermi anomalies simultaneously?
Authors:		Calvez, Antoine; Kusenko, Alexander
Publication:		eprint arXiv:1003.0045
Publication Date:		02/2010
Origin:		ARXIV
Keywords:		Astrophysics - High Energy Astrophysical Phenomena, High Energy Physics - Phenomenology
Comment:		4 pages; version accepted for publication
Bibliographic Code:		2010arXiv1003.0045C

Abstract

Gamma-ray bursts (GRBs) have been invoked to explain both the 511 keV emission from the galactic bulge and the high-energy positron excess inferred from the ATIC, PAMELA, and Fermi data. While independent explanations can be responsible for these phenomena, we explore the possibility of their common GRB-related origin by modeling the GRB distribution and estimating the rates. For an expected Milky Way long GRB rate, neither of the two signals is generic; the local excess requires a 2% coincidence, while the signal from the galactic center requires a 20% coincidence with respect to the timing of the latest GRB. The simultaneous explanation requires a 0.4% coincidence. Considering the large number of statistical ``trials'' created by multiple searches for new physics, the coincidences of a few per cent cannot be dismissed as unlikely. Alternatively, both phenomena can be explained by GRBs if the galactic rate is higher than expected. We also show that a similar result is difficult to obtain assuming a simplified short GRB distribution.

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Ukwatta, T. N. 2010 暴源系中的时延-光度统计关系

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有红移，对Swift暴做的，100-200keV和300-400keV（但BAT不是这个波段呀？）

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Title:		The lag-luminosity relation in the gamma-ray burst source-frame
Authors:		Ukwatta, T. N.; Dhuga, K. S.; Stamatikos, M.; Sakamoto, T.; Parke, W. C.; Barthelmy, S. D.; Gehrels, N.
Publication:		eprint arXiv:1003.0229
Publication Date:		02/2010
Origin:		ARXIV
Keywords:		Astrophysics - High Energy Astrophysical Phenomena
Comment:		Accepted to be published in the Proceedings of "The Shocking Universe - Gamma-Ray Bursts and High Energy Shock Phenomena", Venice (Italy), September 14-18, 2009
Bibliographic Code:		2010arXiv1003.0229U

Abstract

We have investigated the empirical lag-luminosity relation in the Gamma-ray Burst (GRB) source-frame. We selected two energy bands (100-200 keV and 300-400 keV) in the GRB source-frame, which after redshift correction, lie in the observer-frame energy range of the Swift Burst Alert Telescope (BAT). The spectral lags between these energy channels are then presented as a function of the isotropic peak luminosity of the GRBs in the sample.

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Zitouni 2010 假设内急波的情况下模拟伽马暴的光度函数

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Title:		The GRB luminosity function: predictions from the internal shock model and comparison with observations
Authors:		Zitouni, H.; Daigne, F.; Mochkovich, R.; Zerguini, T. H.
Affiliation:		AA(Institut d'Astrophysique de Paris, UMR7095 CNRS, Université Pierre & Marie Curie-Paris 6, 98 bis boulevard Arago, 75014 Paris, France; Université des Sciences et Technologies Houari Boumebedienne, BP 32 16123 Bab-Ezzouar Alger, Algeria), AB(Institut d'Astrophysique de Paris, UMR7095 CNRS, Université Pierre & Marie Curie-Paris 6, 98 bis boulevard Arago, 75014 Paris, France; Institut Universitaire de France), AC(Institut d'Astrophysique de Paris, UMR7095 CNRS, Université Pierre & Marie Curie-Paris 6, 98 bis boulevard Arago, 75014 Paris, France), AD(Université des Sciences et Technologies Houari Boumebedienne, BP 32 16123 Bab-Ezzouar Alger, Algeria)
Publication:		Monthly Notices of the Royal Astronomical Society, Volume 386, Issue 3, pp. 1597-1604. (MNRAS Homepage)
Publication Date:		05/2008
Origin:		MNRAS
MNRAS Keywords:		methods: statistical , stars: luminosity function, mass function , gamma-rays: bursts
DOI:		10.1111/j.1365-2966.2008.13136.x
Bibliographic Code:		2008MNRAS.386.1597Z

Abstract

We compute the expected luminosity function of gamma-ray bursts (GRBs) in the context of the internal shock model. We assume that GRB central engines generate relativistic outflows characterized by the respective distributions of injected kinetic power and contrast in Lorentz factor κ = Γ_max/Γ_min. We find that if the distribution of contrast extends down to values close to unity (i.e. if both highly variable and smooth outflows can exist), then the luminosity function has two branches. At high luminosity it follows the distribution of while at low luminosity it is close to a power law of slope -0.5. We then examine if existing data can constrain the luminosity function. Using the logN-logP curve, the E_p distribution of bright Burst and Transient Source Experiment (BATSE) bursts and the X-ray flash (XRF)/GRB ratio obtained by High Energy Transient Explorer 2 (HETE2), we show that single and broken power laws can provide equally good fits of these data. Present observations are therefore unable to favour one form or the other. However, when a broken power law is adopted they clearly indicate a low-luminosity slope ~= -0.6 +/- 0.2, compatible with the prediction of the internal shock model.

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Beloborodov, A. M. 2010 是否伽马暴余辉本身的辐射就不是各向同性的

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一般理论说余辉在共动系里还是各向同性的。各向同性会抹平任何快速的光变（这个没懂）。不过像同步辐射实际上是各向异性的，如果是的话，可以解释观测到的X射线的快速光变，还有耀发，以及喷流拐折将比较难观测到。

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Title:		Is GRB afterglow emission intrinsically anisotropic ?
Authors:		Beloborodov, A. M.; Daigne, F.; Mochkovitch, R.; Uhm, Z. L.
Publication:		eprint arXiv:1003.1265
Publication Date:		03/2010
Origin:		ARXIV
Keywords:		Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Cosmology and Extragalactic Astrophysics
Comment:		13 pages, 5 figures, submitted to MNRAS
Bibliographic Code:		2010arXiv1003.1265B

Abstract

The curvature of a relativistic blast wave implies that its emission arrives to observers with a spread in time. This effect is believed to wash out any fast variability in the lightcurves of GRB afterglows. We note that the spreading effect is reduced if emission is anisotropic in the rest-frame of the blast wave (i.e. if emission is limb-brightened or limb-darkened). In particular, synchrotron emission is almost certainly anisotropic, and may be strongly anisotropic, depending on details of electron acceleration in the blast wave. Anisotropic afterglows can display fast and strong variability at high frequencies (above the 'fast-cooling' frequency). This may explain the existence of bizarre features in the X-ray afterglows of GRBs, such as sudden drops and flares. We also note that a moderate anisotropy can significantly delay the 'jet break' in the lightcurve, which makes it harder to detect.

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Pe'er, Asaf 2010 伽马暴的热辐射

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Pe'er是个老鼓吹热成分的人。会议论文。

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Title:		Observations, theory and implications of thermal emission from gamma-ray bursts
Authors:		Pe'er, Asaf; Ryde, Felix
Publication:		eprint arXiv:1003.2582
Publication Date:		03/2010
Origin:		ARXIV
Keywords:		Astrophysics - High Energy Astrophysical Phenomena
Comment:		6 pages, Proceedings for "The Shocking Universe - Gamma-Ray Bursts and High Energy Shock phenomena", Venice, 14-18 September 2009.
Bibliographic Code:		2010arXiv1003.2582P

Abstract

Recent analyses show evidence for a thermal emission component that accompanies the non-thermal emission during the prompt phase of GRBs. First, we show the evidence for the existence of this component; Second, we show that this component is naturally explained by considering emission from the photosphere, taking into account high latitude emission from optically thick relativistically expanding plasma. We show that the thermal flux is expected to decay at late times as F_BB ~ t^{-2}, and the observed temperature as T ~ t^{-\alpha}, with \alpha ~ 1/2 - 2/3. These theoretical predictions are in very good agreement with the observations. Finally, we discuss three implications of this interpretation: (a) The relation between thermal emission and high energy, non-thermal spectra observed by Fermi. (b) We show how thermal emission can be used to directly measure the Lorentz factor of the flow and the initial radius of the jet. (c) We show how the lack of detection of the thermal component can be used to constrain the composition of GRB jets.

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Granot 2010 费米观测的几个特征

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提出目前费米暴的特征和对应的问题。
会议论文

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Title:		Highlights from Fermi GRB observations
Authors:		Granot, Jonathan; for the Fermi LAT Collaboration; the GBM Collaboration
Publication:		eprint arXiv:1003.2452
Publication Date:		03/2010
Origin:		ARXIV
Keywords:		Astrophysics - High Energy Astrophysical Phenomena
Comment:		13 pages, 3 figures, 2 tables; to be published in the Proceedings of "The Shocking Universe - Gamma-Ray Bursts and High Energy Shock phenomena", Venice (Italy), September 14-18, 2009 (based on an invited talk there, but updated to include results up to the end of January 2010)
Bibliographic Code:		2010arXiv1003.2452G

Abstract

The Fermi Gamma-Ray Space Telescope has more than doubled the number of Gamma-Ray Bursts (GRBs) detected above 100 MeV within its first year of operation. Thanks to the very wide energy range covered by Fermi's Gamma-ray Burst Monitor (GBM; 8 keV to 40 MeV) and Large Area Telescope (LAT; 25 MeV to >300 GeV) it has measured the prompt GRB emission spectrum over an unprecedentedly large energy range (from ~8 keV to ~30 GeV). Here I briefly outline some highlights from Fermi GRB observations during its first ~1.5 yr of operation, focusing on the prompt emission phase. Interesting new observations are discussed along with some of their possible implications, including: (i) What can we learn from the Fermi-LAT GRB detection rate, (ii) A limit on the variation of the speed of light with photon energy (for the first time beyond the Planck scale for a linear energy dependence from direct time of arrival measurements), (iii) Lower-limits on the bulk Lorentz factor of the GRB outflow (of ~1000 for the brightest Fermi LAT GRBs), (iv) The detection (or in other cases, lack thereof) of a distinct spectral component at high (and sometimes also at low) energies, and possible implications for the prompt GRB emission mechanism, (v) The later onset (and longer duration) of the high-energy emission (>100 MeV), compared to the low-energy (< ~1 MeV) emission, that is seen in most Fermi-LAT GRBs.

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Mundell 2010 Liverpool and Faulkes望远镜对伽马暴余辉的观测

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Title:		Gamma-Ray Bursts in the Era of Rapid Followup
Authors:		Mundell, C. G.; Guidorzi, C.; Steele, I. A.
Publication:		Advances in Astronomy, vol. 2010, pp. 1-15
Publication Date:		00/2010
Origin:		CROSSREF
DOI:		10.1155/2010/718468
Bibliographic Code:		2010AdAst2010E..61M

Abstract

We present a status report on the study of gamma-ray bursts (GRB) in the era of rapid follow-up using the world's largest robotic optical telescopes - the 2-m Liverpool and Faulkes telescopes. Within the context of key unsolved issues in GRB physics, we describe (1) our innovative software that allows real-time automatic analysis and interpretation of GRB light curves, (2) the novel instrumentation that allows unique types of observations (in particular, early time polarisation measurements) and (3) the key science questions and discoveries to which robotic observations are ideally suited, concluding with a summary of current understanding of GRB physics provided by combining rapid optical observations with simultaneous observations at other wavelengths.

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Hashimoto 2010 暗暴GRB 080325是在一个尘埃很多的大质量星系中

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也就是说暗的原因是尘埃咯

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Title:		"Dark" GRB 080325 in a Dusty Massive Galaxy at z ~ 2
Authors:		Hashimoto, T.; Ohta, K.; Aoki, K.; Tanaka, I.; Yabe, K.; Kawai, N.; Aoki, W.; Furusawa, H.; Hattori, T.; Iye, M.; Kawabata, K. S.; Kobayashi, N.; Komiyama, Y.; Kosugi, G.; Minowa, Y.; Mizumoto, Y.; Niino, Y.; Nomoto, K.; Noumaru, J.; Ogasawara, R.; Pyo, T.-S.; Sakamoto, T.; Sekiguchi, K.; Shirasaki, Y.; Suzuki, M.; Tajitsu, A.; Takata, T.; Tamagawa, T.; Terada, H.; Totani, T.; Watanabe, J.; Yamada, T.; Yoshida, A.
Affiliation:		AA(Department of Astronomy, Kyoto University, Kyoto 606-8502, Japan ),
Publication:		The Astrophysical Journal, Volume 719, Issue 1, pp. 378-384 (2010). (ApJ Homepage)
Publication Date:		08/2010
Origin:		IOP
ApJ Keywords:		galaxies: photometry, gamma-ray burst: individual: GRB 080325, gamma rays: galaxies
DOI:		10.1088/0004-637X/719/1/378
Bibliographic Code:		2010ApJ...719..378H

Abstract

We present optical and near-infrared observations of Swift GRB 080325 classified as a "dark gamma-ray burst (GRB)." Near-infrared observations with Subaru/MOIRCS provided a clear detection of afterglow in the K_s band, although no optical counterpart was reported. The flux ratio of rest-wavelength optical to X-ray bands of the afterglow indicates that the dust extinction along the line of sight to the afterglow is A_V = 2.7-10 mag. This large extinction is probably the major reason for the optical faintness of GRB 080325. The J – K_s color of the host galaxy, (J – K_s = 1.3 in AB magnitude), is significantly redder than those for typical GRB hosts previously identified. In addition to J and K_s bands, optical images in B, R_c , i', and z' bands with Subaru/Suprime-Cam were obtained at about 1 year after the burst, and a photometric redshift of the host is estimated to be z _photo = 1.9. The host luminosity is comparable to L* at z ~ 2 in contrast to the sub-L* property of typical GRB hosts at lower redshifts. The best-fit stellar population synthesis model for the host shows that the red nature of the host is attributed to a large dust extinction (A_V = 0.8 mag), and that the host galaxy is massive (M* = 7.0 × 10¹⁰ M _sun), which makes it one of the most massive GRB hosts yet identified. By assuming that the mass-metallicity relation for star-forming galaxies at z ~ 2 is applicable for the GRB host, this large stellar mass suggests the high-metallicity environment around GRB 080325, consistent with inferred large extinction. Based on data collected at Subaru Telescope, which is operated by the National Astronomical Observatory of Japan.

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Robinson, Peter B. 2010 前身星的紫外发射线

主要内容:
他们计算前身星喷出的物质的发射线，发现可以印证告诉运动的线不能被观测到。说以前看到的那些高速线挺奇怪。

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Title:		The rest-frame ultraviolet spectra of GRBs from massive rapidly rotating stellar progenitors
Authors:		Robinson, Peter B.; Perna, Rosalba; Lazzati, Davide; van Marle, Allard J.
Affiliation:		AA(JILA, University of Colorado, 440 UCB, Boulder, CO 80309-0440, USA), AB(JILA, University of Colorado, 440 UCB, Boulder, CO 80309-0440, USA), AC(Department of Physics, NC State University, Campus Box 8202, Raleigh, NC 27695-8202, USA), AD(Bartol Research Institute, University of Delaware, 102 Sharp Laboratory, Newark, DE 19716, USA)
Publication:		Monthly Notices of the Royal Astronomical Society, Volume 401, Issue 1, pp. 88-98. (MNRAS Homepage)
Publication Date:		01/2010
Origin:		WILEY
MNRAS Keywords:		line: formation, methods: numerical, supernovae: general, gamma-rays: bursts, gamma-rays: theory
DOI:		10.1111/j.1365-2966.2009.15672.x
Bibliographic Code:		2010MNRAS.401...88R

Abstract

The properties of a massive star prior to its final explosion are imprinted in the circumstellar medium (CSM) created by its wind and termination shock. We perform a detailed, comprehensive calculation of the time-variable and angle-dependent transmission spectra of an average-luminosity gamma-ray burst (GRB) which explodes in the CSM structure produced by the collapse of a 20 M_solar, rapidly rotating, Z = 0.001 progenitor star. We study both the case in which metals are initially in the gaseous phase and the situation in which they are heavily depleted into dust. We find that high-velocity lines from low-ionization states of silicon, carbon and iron are initially present in the spectrum only if the metals are heavily depleted into dust prior to the GRB explosion. However, such lines disappear on time-scales of a fraction of a second for a burst observed on-axis, and of a few seconds for a burst seen at high latitude, making their observation virtually impossible. Rest-frame lines produced in the termination shock are instead clearly visible in all conditions. We conclude that time-resolved, early-time spectroscopy is not a promising way in which the properties of the GRB progenitor wind can be routinely studied. Previous detections of high-velocity features in GRB ultraviolet spectra must have been either due to a superposition of a physically unrelated absorber or due to a progenitor star with very unusual properties.

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Foschini 2010 天体物理中的喷流

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科普性质的小综述

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Title:		Jets (relativistic and non) in astrophysics
Authors:		Foschini, Luigi
Publication:		eprint arXiv:1003.4212
Publication Date:		03/2010
Origin:		ARXIV
Keywords:		Physics - Popular Physics, Astrophysics - Galaxy Astrophysics, Astrophysics - High Energy Astrophysical Phenomena
Comment:		7 pages, no figures, 1 table. English translation of the article originally published in Italian on the popular science magazine "Le Stelle", n. 82, March 2010.
Bibliographic Code:		2010arXiv1003.4212F

Abstract

Let's take stock of the situation on one of the most studied astrophysical phenomena during the latest years: the jets escaping from protostars, stellar singularities, GRB and active galactic nuclei.

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Pandey, S. B. 2010 GRB 090902B的余辉观测

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余辉的光变

1.9天时的谱

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Title:		GRB 090902B: Afterglow Observations and Implications
Authors:		Pandey, S. B.; Swenson, C. A.; Perley, D. A.; Guidorzi, C.; Wiersema, K.; Malesani, D.; Akerlof, C.; Ashley, M. C. B.; Bersier, D.; Cano, Z.; Gomboc, A.; Ilyin, I.; Jakobsson, P.; Kleiser, I. K. W.; Kobayashi, S.; Kouveliotou, C.; Levan, A. J.; McKay, T. A.; Melandri, A.; Mottram, C. J.; Mundell, C. G.; O'Brien, P. T.; Phillips, A.; Rex, J. M.; Siegel, M. H.; Smith, R. J.; Steele, I. A.; Stratta, G.; Tanvir, N. R.; Weights, D.; Yost, S. A.; Yuan, F.; Zheng, W.
Affiliation:
Publication:		The Astrophysical Journal, Volume 714, Issue 1, pp. 799-804 (2010). (ApJ Homepage)
Publication Date:		05/2010
Origin:		IOP
ApJ Keywords:		gamma-ray burst: general
DOI:		10.1088/0004-637X/714/1/799
Bibliographic Code:		2010ApJ...714..799P

Abstract

The optical-infrared afterglow of the Large Area Telescope (LAT)-detected long-duration burst, GRB 090902B, has been observed by several instruments. The earliest detection by ROTSE-IIIa occurred 80 minutes after detection by the Gamma-ray Burst Monitor instrument on board the Fermi Gamma-Ray Space Telescope, revealing a bright afterglow and a decay slope suggestive of a reverse shock origin. Subsequent optical-IR observations followed the light curve for 6.5 days. The temporal and spectral behavior at optical-infrared frequencies is consistent with synchrotron fireball model predictions; the cooling break lies between optical and XRT frequencies ~1.9 days after the burst. The inferred electron energy index is p = 1.8 ± 0.2, which would however imply an X-ray decay slope flatter than observed. The XRT and LAT data have similar spectral indices and the observed steeper value of the LAT temporal index is marginally consistent with the predicted temporal decay in the radiative regime of the forward shock model. Absence of a jet break during the first 6 days implies a collimation-corrected γ-ray energy E _γ > 2.2 × 10⁵² erg, one of the highest ever seen in a long-duration gamma-ray bursts. More events combining GeV photon emission with multiwavelength observations will be required to constrain the nature of the central engine powering these energetic explosions and to explore the correlations between energetic quanta and afterglow emission.

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