Rowlinson 2010 短暴GRB 090515可能是磁星

主要内容:
此暴的特点：时标非常短，0.036s，光度低，余辉暗。

精彩摘抄:

该短暴的光变

红点是 GRB 090515所处的位置

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Title:		The unusual X-ray emission of the short Swift GRB 090515: Evidence for the formation of a magnetar?
Authors:		Rowlinson, A.; O'Brien, P. T.; Tanvir, N. R.; Zhang, B.; Evans, P. A.; Lyons, N.; Levan, A. J.; Willingale, R.; Page, K. L.; Onal, O.; Burrows, D. N.; Beardmore, A. P.; Ukwatta, T. N.; Berger, E.; Hjorth, J.; Fruchter, A. S.; Tunnicliffe, R. L.; Fox, D. B.; Cucchiara, A.
Publication:		eprint arXiv:1007.2185
Publication Date:		07/2010
Origin:		ARXIV
Keywords:		Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Cosmology and Extragalactic Astrophysics
Comment:		10 pages, 7 figures, MNRAS accepted
Bibliographic Code:		2010arXiv1007.2185R

Abstract

The majority of short gamma-ray bursts (SGRBs) are thought to originate from the merger of compact binary systems collapsing directly to form a black hole. However, it has been proposed that both SGRBs and long gamma-ray bursts (LGRBs) may, on rare occasions, form an unstable millisecond pulsar (magnetar) prior to final collapse. GRB 090515, detected by the Swift satellite was extremely short, with a T_90 of 0.036 +/- 0.016 s, and had a very low fluence of 2 x 10^-8 erg cm^-2 and faint optical afterglow. Despite this, the 0.3 - 10 keV flux in the first 200 s was the highest observed for a SGRB by the Swift X-ray Telescope (XRT). The X-ray light curve showed an unusual plateau and steep decay, becoming undetectable after ~500 s. This behaviour is similar to that observed in some long bursts proposed to have magnetars contributing to their emission. In this paper, we present the Swift observations of GRB 090515 and compare it to other gamma-ray bursts (GRBs) in the Swift sample. Additionally, we present optical observations from Gemini, which detected an afterglow of magnitude 26.4 +/- 0.1 at T+ 1.7 hours after the burst. We discuss potential causes of the unusual 0.3 - 10 keV emission and suggest it might be energy injection from an unstable millisecond pulsar. Using the duration and flux of the plateau of GRB 090515, we place constraints on the millisecond pulsar spin period and magnetic field.

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Pe'er, Asaf 2010 伽马暴的热成分及GRB090902B

主要内容:
认为暴本身的辐射是多温度的黑体辐射，高能部分是同步辐射、SSC和暴本身辐射的IC的混合。

精彩摘抄:

GRB 090902B的谱

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Title:		The Connection Between Thermal and Non-Thermal Emission in Gamma-ray Bursts: General Considerations and GRB090902B as a Case Study
Authors:		Pe'er, Asaf; Zhang, Bin-Bin; Ryde, Felix; McGlynn, Sinéad; Zhang, Bing; Preece, Robert D.; Kouveliotou, Chryssa
Publication:		eprint arXiv:1007.2228
Publication Date:		07/2010
Origin:		ARXIV
Keywords:		Astrophysics - High Energy Astrophysical Phenomena
Comment:		12 pages, 5 figures; Figures resolution reduced to comply with file size restriction. Submitted for publication in Ap.J
Bibliographic Code:		2010arXiv1007.2228P

Abstract

Photospheric (thermal) emission is inherent to the gamma-ray burst (GRB) "fireball" model. We show here, that inclusion of this component in the analysis of the GRB prompt emission phase naturally explains some of the prompt GRB spectra seen by the Fermi satellite over its entire energy band. The sub-MeV peak is explained as multi-color black body emission, and the high energy tail, extending up to the GeV band, results from roughly similar contributions of synchrotron emission, synchrotron self Compton (SSC) and Comptonization of the thermal photons by energetic electrons originating after dissipation of the kinetic energy above the photosphere. We show how this analysis method results in a complete, self consistent picture of the physical conditions at both emission sites of the thermal and non-thermal radiation. We study the connection between the thermal and non-thermal parts of the spectrum, and show how the values of the free model parameters are deduced from the data. We demonstrate our analysis method on GRB090902B: We deduce a Lorentz factor in the range 780 <= \eta <= 1000, photospheric radius r_{ph} ~ 6.1 - 7.8*10^{11} cm and dissipation radius r_\gamma >= 3.8 - 5.0*10^{15} cm. By comparison to afterglow data, we deduce that a large fraction, \epsilon_d ~ 85% - 95% of the kinetic energy is dissipated, and that large fraction, ~equipartition of this energy is carried by the electrons and the magnetic field. This high value of \epsilon_d questions the "internal shock" scenario as the main energy dissipation mechanism for this GRB.

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Penate 2010 伽马暴对海洋光合作用的短期影响

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Title:		Short-term effects of Gamma Ray Bursts on oceanic photosynthesis
Authors:		Penate, Liuba; Martin, Osmel; Cardenas, Rolando; Agusti, Susana
Publication:		eprint arXiv:1007.2879
Publication Date:		07/2010
Origin:		ARXIV
Keywords:		Astrophysics - Earth and Planetary Astrophysics
Comment:		Accepted for publication in Astrophysics and Space Science
Bibliographic Code:		2010arXiv1007.2879P

Abstract

We continue our previous work on the potential short-term influence of a gamma ray bursts on Earth's biosphere, focusing on the only important short-term effect on life: the ultraviolet flash which occurs as a result of the retransmission of the {\gamma} radiation through the atmosphere. Thus, in this work we calculate the ultraviolet irradiances penetrating the first hundred meters of the water column, for Jerlov's ocean water types I, II and III. Then we estimate the UV flash potential for photosynthesis inhibition, showing that it can be important in a considerable part of the water column with light enough for photosynthesis to be done, the so called photic zone.

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Ackermann 2010 Fermi对GRB 090217A的观测

主要内容:
给出了GRB 090217A的观测，不想其他一般的高能暴，高能部分并没有时间上的延迟。

精彩摘抄:

光变

谱

谱指数

谱指数


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Title:		Fermi Observations of High-energy Gamma-ray Emission from GRB 090217A
Authors:		Ackermann, M.; Ajello, M.; Baldini, L.; et al.
Affiliation:		too many
Publication:		The Astrophysical Journal Letters, Volume 717, Issue 2, pp. L127-L132 (2010). (ApJL Homepage)
Publication Date:		07/2010
Origin:		IOP
ApJ Keywords:		gamma-ray burst: individual: GRB090217A
DOI:		10.1088/2041-8205/717/2/L127
Bibliographic Code:		2010ApJ...717L.127A

Abstract

The Fermi observatory is advancing our knowledge of gamma-ray bursts (GRBs) through pioneering observations at high energies, covering more than seven decades in energy with the two on-board detectors, the Large Area Telescope (LAT) and the Gamma-ray Burst Monitor (GBM). Here, we report on the observation of the long GRB 090217A which triggered the GBM and has been detected by the LAT with a significance greater than 9σ. We present the GBM and LAT observations and on-ground analyses, including the time-resolved spectra and the study of the temporal profile from 8 keV up to ~1 GeV. All spectra are well reproduced by a Band model. We compare these observations to the first two LAT-detected, long bursts GRB 080825C and GRB 080916C. These bursts were found to have time-dependent spectra and exhibited a delayed onset of the high-energy emission, which are not observed in the case of GRB 090217A. We discuss some theoretical implications for the high-energy emission of GRBs.

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Neronov 2010 磁化外流体的质子辐射作为伽马暴的辐射机制

主要内容:

质子占主导的small pitch angle synchrotron emission辐射MeV的光子，低能段能产生光子谱指数为-1或者0。

精彩摘抄:

谱

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Title:		Gamma ray emission from magnetized relativistic GRB outflows
Authors:		Neronov, A.; Savchenko, V.
Publication:		eprint arXiv:1007.3288
Publication Date:		07/2010
Origin:		ARXIV
Keywords:		Astrophysics - High Energy Astrophysical Phenomena
Comment:		5 pages, 1 figure, accepted for publication in A&A letters; doi:10.1051/0004-6361/201015212
Bibliographic Code:		2010arXiv1007.3288N

Abstract

We argue that small pitch angle synchrotron emission provides an important dissipation mechanism which has to be taken into account in the models of formation of relativistic magnetized gamma-ray burst (GRB) outflows from the newborn black holes and/or magnetars. We show that if the GRB outflow is proton loaded, spectral energy distribution of this emission is expected to sharply peak in 0.1-1~MeV energy band. If the small pitch angle synchrotron emission efficiently cools relativistic particles of the outflow, its spectrum below the peak energy is a powerlaw with spectral index alpha ~ -1, close to the typical spectral index of the time-resolved GRB spectra. Otherwise, the low energy spectral index can be as hard as alpha ~ 0, as observed at the beginning of the GRB pulses. We make a conjecture that small pitch angle synchrotron emission from proton-loaded magnetized GRB outflow could significantly contribute to the Band component of the prompt emission of GRBs while electromagnetic cascade initiated by the protons could be responsible for the GeV component.

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Zou 2010 高能和低能辐射来自两个区域的时候对洛仑兹因子的限制

主要内容:
考虑MeV和GeV辐射是来自不同的区域，GeV的产生于更大半径处，考虑GeV光子被MeV光子吸收的几率，也即光深，来限制洛仑兹因子。比单一辐射区的限制要松，只需大于几百就可以了，而不是上千。

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Title:		A Revised Limit of the Lorentz Factors of GRBs with Two Emitting Regions
Authors:		Zou, Yuan-Chuan; Fan, Yi-Zhong; Piran, Tsvi
Publication:		eprint arXiv:1008.2253
Publication Date:		08/2010
Origin:		ARXIV
Keywords:		Astrophysics - High Energy Astrophysical Phenomena
Comment:		15 pages 4 figuers
Bibliographic Code:		2010arXiv1008.2253Z

Abstract

Fermi observations of GeV emission from GRBs have suggested that the Lorentz factor of some GRBs is around a thousand or even higher. At the same time the same Fermi observations have shown an extended GeV emission indicating that this higher energy emission might be a part of the afterglow and it does not come from the same region as the lower energy prompt emission. If this interpretation is correct than we should reconsider the opacity limits on the Loretnz factor of the emitting regions which are based on a one-zone model. We describe here a two-zone model in which the GeV photons are emitted in a larger radius than the MeV photons and we calculate the optical depth for pair creation of a GeV photon passing the lower energy photons shell. We find that, as expected, the new two-zone limits on the Lorentz factor are significantly lower. The corresponding limits for the Fermi bursts are lower by a factor of ?two to five compared to the one-zone model and it is possible that both the MeV and GeV regions have relatively modest Lorentz factors (~200 - 400).

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Biesiada 2010 将洛仑兹违背的时延应用于其他宇宙学模型

主要内容:
以前的时延都是基于标准宇宙学模型的，此文将其他宇宙学模型也考虑进来：four alternative models of dark energy (quintessence with constant and variable equation of state, Chaplygin gas and braneworld cosmology).

注意不是用其他的引力模型（导致不一样的洛仑兹违背），而是考虑不同的宇宙学模型（应该是导致不同的距离，从而有不同的时延吧。）

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Title:		Lorentz invariance violation-induced time delays in GRBs in different cosmological models
Authors:		Biesiada, Marek; Piórkowska, Aleksandra
Affiliation:		AA(Institute of Physics, Department of Astrophysics and Cosmology, University of Silesia, Uniwersytecka 4, 40-007 Katowice, Poland biesiada@us.edu.pl), AB(Institute of Physics, Department of Astrophysics and Cosmology, University of Silesia, Uniwersytecka 4, 40-007 Katowice, Poland biesiada@us.edu.pl)
Publication:		Classical and Quantum Gravity, Volume 26, Issue 12, pp. 125007 (2009). (CQGra Homepage)
Publication Date:		06/2009
Origin:		IOP
DOI:		10.1088/0264-9381/26/12/125007
Bibliographic Code:		2009CQGra..26l5007B

Abstract

Lorentz invariance violation (LIV) manifesting itself by energy-dependent modification of standard relativistic dispersion relation has recently attracted a considerable attention. Ellis et al previously investigated the energy-dependent time offsets in different energy bands on a sample of gamma ray bursts and, assuming standard cosmological model, they found a weak indication for redshift dependence of time delays suggestive of LIV. Going beyond the ΛCDM cosmology we extend this analysis considering also four alternative models of dark energy (quintessence with constant and variable equation of state, Chaplygin gas and braneworld cosmology). It turns out that the effect noted by Ellis et al is also present in those models and is the strongest for quintessence with a variable equation of state.

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Dai, Shi 2010 用夸克物质相变来解释X射线余辉的变平

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Title:		The Plateau of Gamma-ray Burst: Hint for the Solidification of Quark Matter?
Authors:		Dai, Shi; Li, Lixin; Xu, Renxin
Publication:		eprint arXiv:1008.2568
Publication Date:		08/2010
Origin:		ARXIV
Keywords:		Astrophysics - High Energy Astrophysical Phenomena
Comment:		5 pages, 1 figures. Submitted to Science China Press
Bibliographic Code:		2010arXiv1008.2568D

Abstract

The origin of the shallow decay segment in gamma-ray burst's (GRB) early light curves remains a mystery, especially those cases with a long-lived plateau followed by an abrupt falloff. In this paper, we propose a mechanism to understand the origin of the abrupt falloff after plateau by considering solidification of newborn quark stars with latent heat released as energy injection to GRB afterglow. We estimate the total latent heat released during the phase transition of quark stars from liquid to solid states, to be order of ~ 10^{51}ergs, which is comparable to the emission energy in the shallow decay segment. We also estimate the time scale of radiating the latent heat through thermal photon emission, and find that the time scale agrees with observations. Based on our estimation, we analyze the process of energy injection to GRB afterglow. We show that the steady latent heat of quark star phase transition would continuously inject into GRB afterglow in a form similar to that of a Poyntingflux- dominated outflow and naturally produce the shallow decay phase and the abrupt falloff after plateau. We conclude that the latent heat of quark star phase transition would be an important contribution to the shallow decay radiation in GRB afterglow, and would explain the general features of GRB light curves (including the plateau), if pulsar-like stars are really (solid) quark stars.

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Campana 2010 用X射线探测超高红移的伽马暴

主要内容:
从而以伽马暴为工具探测超高红移宇宙。
（因为红移越高，所观测的波段能量越低。所以要用X射线仪器）

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Title:		Probing the very high redshift Universe with Gamma-ray Bursts: prospects for observations with future X-ray instruments
Authors:		Campana, S.; Salvaterra, R.; Tagliaferri, G.; Kouveliotou, C.; Grindlay, J.
Publication:		eprint arXiv:1008.3054
Publication Date:		08/2010
Origin:		ARXIV
Keywords:		Astrophysics - High Energy Astrophysical Phenomena
Comment:		Accepted for publication on MNRAS (1 figure, 3 tables)
Bibliographic Code:		2010arXiv1008.3054C

Abstract

Gamma-Ray Bursts (GRBs) are the most violent explosions in the Universe. Long duration GRBs are associated with the collapse of massive stars, rivaling their host galaxies in luminosity. The discovery of the most distant spectroscopically confirmed object in the Universe, GRB090423, opened a new window on the high redshift Universe, making it possible to study the cosmic 're-ionization' epoch and the preceding dark ages, as well as the generation of the first stars (Population III) using GRBs. Obviously this enables a wealth of new studies using the near infrared (nIR) characteristics of GRB afterglows. Here we explore a different path, focusing on the next generation of X-ray missions with large area focusing telescopes and fast repointing capabilities. We found that X-ray data can complement nIR observations and for the brightest GRBs can provide an accurate and independent redshift determination. Metallicity studies can also be carried out profitably once the redshift is known. Finally we discuss observational signatures of GRBs arising from Population III stars in the X-ray band.

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Grindlay, Jonathan E. 2010 EXIST可以看到更多高红移的伽马暴

主要内容:
原因是比Swift更灵敏

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Title:		GRB Probes of the Early Universe with EXIST
Authors:		Grindlay, Jonathan E.
Publication:		eprint arXiv:1008.3280
Publication Date:		08/2010
Origin:		ARXIV
Keywords:		Astrophysics - Cosmology and Extragalactic Astrophysics
Comment:		8 pages, 4 figures, 1 table. Invited talk at Kyoto Conference (April 2010), "Deciphering the Ancient Universe with Gamma-Ray Bursts". To appear in AIPC (N. Kawai and S. Nagataki, eds.), 2010 in press
Bibliographic Code:		2010arXiv1008.3280G

Abstract

With the Swift detection of GRB090423 at z = 8.2, it was confirmed that GRBs are now detectable at (significantly) larger redshifts than AGN, and so can indeed be used as probes of the Early Universe. The proposed Energetic X-ray Imaging Survey Telescope (EXIST) mission has been designed to detect and promptly measure redshifts and both soft X-ray (0.1 - 10 keV) and simultaneous nUV-nIR (0.3 - 2.3microns) imaging and spectra for GRBs out to redshifts z ~18, which encompasses (or even exceeds) current estimates for Pop III stars that are expected to be massive and possibly GRB sources. Scaling from Swift for the ~10X greater sensitivity of EXIST, more than 100 GRBs at z >=8 may be detected and would provide direct constraints on the formation and evolution of the first stars and galaxies. For GRBs at redshifts z >= 8, with Lyman breaks at greater than 1.12microns, spectra at resolution R = 30 or R = 3000 for afterglows with AB magnitudes brighter than 24 or 20 (respectively) within ~3000sec of trigger will directly probe the Epoch of Reionization, formation of galaxies, and cosmic star formation rate. The proposed EXIST mission can probe these questions, and many others, given its unparalleled combination of sensitivity and spatial-spectral-temporal coverage and resolution. Here we provide an overview of the key science objectives for GRBs as probes of the early Universe and of extreme physics, and the mission plan and technical readiness to bring this to EXIST.

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