Fermi sensitivity

LAT:
http://www-glast.slac.stanford.edu/software/IS/glast_lat_performance-old3.htm

貌似对于暂现源的判断是有5个光子的流量就可以算探测到了. 而极限流量也由此而算出来.

Medvedev 2009 jitter emission

主要内容:
可以解释同步的"死线"

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Title:		Modeling Spectral Variability of Prompt GRB Emission within the Jitter Radiation Paradigm
Authors:		Medvedev, Mikhail V.; Pothapragada, Sriharsha S.; Reynolds, Sarah J.
Publication:		eprint arXiv:0902.4244
Publication Date:		02/2009
Origin:		ARXIV
Keywords:		Astrophysics - High Energy Astrophysical Phenomena
Comment:		4 pages. Submitted to ApJL
Bibliographic Code:		2009arXiv0902.4244M

Abstract

The origin of rapid spectral variability and certain spectral correlations of the prompt gamma-ray burst emission remains an intriguing question. The recently proposed theoretical model of the prompt emission is build upon unique spectral properties of jitter radiation -- the radiation from small-scale magnetic fields generated at a relativistic collisionless shock. Here we present the results of numerical implementation of the model. We show that anisotropy of the jitter radiation pattern and relativistic shock kinematics altogether produce effects commonly observed in time-resolved spectra of prompt emission, e.g., the softening of the spectrum below the peak energy within individual pulses in the prompt light-curve, the so-called "tracking" behavior (correlation of the observed flux with other spectral parameters), the emergence of hard, synchrotron-violating spectra at the beginning of individual spikes. Several observational predictions of the model are discussed.

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Pollack 2009 GRB060418 附近星系的MgII吸收线

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Title:		An Imaging and Spectroscopic Study of Four Strong MgII Absorbers Revealed By GRB060418
Authors:		Pollack, L. K.; Chen, H. -W.; Prochaska, J. X.; Bloom, J. S.
Publication:		eprint arXiv:0902.3661
Publication Date:		02/2009
Origin:		ARXIV
Keywords:		Astrophysics - Cosmology and Extragalactic Astrophysics
Comment:		12 ApJ style pages, 5 figures; submitted to ApJ
Bibliographic Code:		2009arXiv0902.3661P

Abstract

We present results from an imaging and spectroscopic study of four strong MgII absorbers of W(2796) >~ 1 Ang revealed by the afterglow of GRB060418 at z_GRB=1.491. These absorbers, at z=0.603,0.656,1.107 and z_GRB, exhibit large ion abundances that suggest neutral gas column densities characteristic of damped Lya systems. The imaging data include optical images obtained using LRIS on the Keck I telescope and using ACS on board HST, and near-infrared H-band images obtained using PANIC on the Magellan Baade Telescope and K'-band images obtained using NIRC2 with LGSAO on the Keck II telescope. These images reveal six distinct objects at <~ 3.5'' of the afterglow's position, two of which exhibit well-resolved mature disk morphology, one shows red colors, and three are blue compact sources. Follow-up spectroscopic observations using LRIS confirm that one of the disk galaxies coincides with the MgII absorber at z=0.656. The observed broad-band spectral energy distributions of the second disk galaxy and the red source indicate that they are associated with the absorbers at z=0.603 and z=1.107, respectively. These results show that strong MgII absorbers identified in GRB afterglow spectra are associated with typical galaxies of luminosity ~ (0.1-1) L* at impact parameter <~ 10 h^-1 kpc. The close angular separation would preclude easy detections toward a bright quasar. Finally, we associate the remaining three blue compact sources with the GRB host galaxy, noting that they are likely star-forming knots located at projected distances 2-12 h^-1 kpc from the afterglow. At the afterglow's position, we derive a 2-sigma upper limit to the underlying SFR intensity of 0.0074 M_sun yr^-1 kpc^-2.

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Williams 2009 What Are Gamma-Ray Bursts

主要内容:
小综述

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Title:		What Are Gamma-Ray Bursts -- The Unique Role of Very High Energy Gamma-Ray Observations
Authors:		Williams, D. A.; Falcone, A. D.; Baring, M. G.; Buckley, J.; Connaughton, V.; Coppi, P.; Dermer, C.; Digel, S.; Dingus, B.; Fryer, C.; Gehrels, N.; Granot, J.; Horan, D.; Katz, J. I.; Meszaros, P.; Norris, J.; Saz Parkinson, P.; Pe'er, A.; Razzaque, S.; Sinnis, G.; Wang, X. Y.; Weekes, T. C.; Zhang, B.
Publication:		eprint arXiv:0902.3466
Publication Date:		02/2009
Origin:		ARXIV
Keywords:		Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Instrumentation and Methods for Astrophysics
Comment:		White paper contributed to the Stars and Stellar Evolution Science Frontier Panel of the Astro2010 Decadal Survey
Bibliographic Code:		2009arXiv0902.3466W

Abstract

Gamma-ray bursts (GRBs) have been an enigma since their discovery forty years ago. However, considerable progress unraveling their mysteries has been made in recent years. Developments in observations, theory, and instrumentation have prepared the way so that the next decade can be the one in which we finally answer the question, "What are gamma-ray bursts?" This question encompasses not only what the progenitors are that produce the GRBs, but also how the enormous luminosity of the GRBs, concentrated in gamma rays, is achieved. Observations across the electromagnetic spectrum, from both the ground and space, will be required to fully tackle this important question. This white paper, mostly distilled from a recent study commissioned by the Division of Astrophysics of the American Physical Society, focuses on what very high energy (~100 GeV and above) gamma-ray observations can contribute. Very high energy gamma rays probe the most extreme high energy particle populations in the burst environment, testing models of lepton and proton acceleration in GRBs and constraining the bulk Lorentz factor and opacity of the outflow. Sensitivity improvements of more than an order of magnitude in the very high energy gamma-ray band can be achieved early in the next decade, in order to contribute to this science.

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Greiner 2009 用核子共振的吸收线作为高能仪器的原理

主要内容:
号称可以探测z=20-60的暴 (?)

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Title:		Nuclear Resonances: The quest for large column densities and a new tool
Authors:		Greiner, J.; Boggs, S. E.; DiCocco, G.; Freese, K. T.; Gehrels, N.; Hartmann, D. H.; Iyudin, A.; Kanbach, G.; Zdziarski, A. A.
Publication:		eprint arXiv:0902.3525
Publication Date:		02/2009
Origin:		ARXIV
Keywords:		Astrophysics - Instrumentation and Methods for Astrophysics, Astrophysics - High Energy Astrophysical Phenomena
Comment:		White Paper subm. to Decadal Survey
Bibliographic Code:		2009arXiv0902.3525G

Abstract

Nuclear physics offers us a powerful tool: using nuclear resonance absorption lines to infer the physical conditions in astrophysical settings which are otherwise difficult to deduce. Present-day technology provides an increase in sensitivity over previous gamma-ray missions large enough to utilize this tool for the first time. The most exciting promise is to measure gamma-ray bursts from the first star(s) at redshifts 20-60, but also active galactic nuclei are promising targets.

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Liang 2009 XRT光变的单一幂律下降

主要内容:
共17个

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Title:		A Comprehensive Analysis of Swift/XRT Data: IV. Single Power-Law Decaying XRT lightcurves and Implications for the Unified Origin of the X-rays
Authors:		Liang, En-Wei; Lv, Hou-Jun; Zhang, Bin-Bin; Zhang, Bing
Publication:		eprint arXiv:0902.3504
Publication Date:		02/2009
Origin:		ARXIV
Keywords:		Astrophysics - High Energy Astrophysical Phenomena
Comment:		29 pages, including 2 tables and 8 figures. Submitted to ApJ. This is the forth paper of a series. Paper I, II, and III see astro-ph/0612246 (ApJ, 2007, 666,1002), arXiv:0705.1373 (ApJ, 2007, 670, 565), and arXiv:0708.2942 (ApJ, 2008, 675, 528)
Bibliographic Code:		2009arXiv0902.3504L

Abstract

By analyzing the Swift/XRT lightcurves detected before 2008 October, we find 17 cases that decay as a single power law (SPL) from tens of seconds to ~10^5 seconds post the GRB trigger. They are apparently different from the canonical ones that are characterized by a shallow-to-normal decay transition. We compare the distributions of the observables of the prompt gamma-rays and X-rays for the two groups of GRBs, but no statistical difference is found. Interestingly, the SPL XRT lightcurves in the burst frame merge into a conflux. The normal decay segment for the canonical lightcurves has the similar feature. These results likely suggest that both the prompt gamma-rays and the X-rays for the two groups of GRBs may share the similar physical origins, and the apparent difference between the groups of XRT lightcurves may not be intrinsic. If the shallow decay is due to energy injection into the fireball, this suggests that the total energy budget after injection for both types of GRBs is similar. More intriguingly, the picture is consistent with the scenario that the apparent shallow-to-normal behavior is an artifact because of the improper choice of the zero time point (T_0), as suggested by Yamazaki. We shift T_0 of the canonical lightcurves to an epoch prior to the GRB triggers to make the lightcurves close to a SPL with the temporal indices similar to those in the normal decay phase. It is found that the T_0-shifted lightcurves trace the lightcurves of the SPL type well. This result likely suggests that the X-rays might be a long-lasting emission component that is independent of the prompt gamma-rays. The GRBs with the SPL lightcurves may be those whose T_0's of X-ray decay are comparable to the trigger times. We discuss the prior X-ray emission from GRBs for both an external shock origin and an origin from a long-lasting central engine.

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McQuinn 2009 伽玛暴探测早期的第一代恒星和再电离阶段

主要内容:
白皮书一部分.

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Title:		In Situ Probes of the First Galaxies and Reionization: Gamma-ray Bursts
Authors:		McQuinn, Matthew; Bloom, Joshua S.; Grindlay, Jonathan; Band, David; Barthelmy, S. D.; Berger, E.; Corsi, A.; Covino, S.; Fishman, G. J.; Furlanetto, Steven R.; Gehrels, Neil; Hartmann, D. H.; Kouveliotou, Chryssa; Kutyrev, A. S.; Loeb, Abraham; Moseley, S. Harvey; Piran, Tsvi; Piro, L.; Prochaska, J. X.; Salvaterra, R.; Schady, P.; Soderberg, A. M.; Tagliaferri, G.
Publication:		eprint arXiv:0902.3442
Publication Date:		02/2009
Origin:		ARXIV
Keywords:		Astrophysics - Cosmology and Extragalactic Astrophysics, Astrophysics - Solar and Stellar Astrophysics
Comment:		8 pages, 3 figures, science white paper submitted to the US Astro2010 Decadal Survey
Bibliographic Code:		2009arXiv0902.3442M

Abstract

The first structures in the Universe formed at z>7, at higher redshift than all currently known galaxies. Since GRBs are brighter than other cosmological sources at high redshift and exhibit simple power-law afterglow spectra that is ideal for absorption studies, they serve as powerful tools for studying the early universe. New facilities planned for the coming decade will be able to obtain a large sample of high-redshift GRBs. Such a sample would constrain the nature of the first stars, galaxies, and the reionization history of the Universe.

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Dai 2009 LBT and MDM对5个暴的晚期余辉的观测

主要内容:
(会议文集, 给的不是很详细).

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Title:		Late-Time Optical Afterglow Observations with LBT and MDM
Authors:		Dai, X.; Stanek, K. Z.; Garnavich, P. M.
Affiliation:		AA(Department of Astronomy, Ohio State University, Columbus, OH 43210, USA), AB(Department of Astronomy, Ohio State University, Columbus, OH 43210, USA), AC(Department of Physics, University of Notre Dame, Notre Dame, IN 46556, USA)
Publication:		2008 NANJING GAMMA-RAY BURST CONFERENCE. AIP Conference Proceedings, Volume 1065, pp. 93-97 (2008). (AIPC Homepage)
Publication Date:		10/2008
Origin:		AIP
Keywords:		afterglows, telescopes, gamma-ray sources (astronomical), supernovae
Abstract Copyright:		(c) 2008: American Institute of Physics
DOI:		10.1063/1.3027966
Bibliographic Code:		2008AIPC.1065...93D

Abstract

Using the 2.4m MDM and 8.4m Large Binocular Telescope, we observed nine GRB afterglows to systematically probe the late time behaviors of afterglows including jet breaks, flares, and supernova bumps. In particular, the LBT observations have typical flux limits of 25-26 mag in the Sloan r' band, which allows us to extend the temporal baseline for measuring jet breaks by another decade in time scale. We detected four jet breaks (including a ``textbook'' jet break in GRB070125) and a fifth candidate, all of which are not detectable without deep, late time optical observations. In the other four cases, we do not detect the jet breaks either because of contamination from the host galaxy light, the presence of a supernova bump, or the intrinsic faintness of the optical afterglow. This suggests that the basic picture that GRBs are collimated is still valid and that the apparent lack of Swift jet breaks is due to poorly sampled afterglow light curves, particularly at late times. Besides the jet breaks, we also detected late time flares, which could attribute to late central engine activities, and two supernova bumps.

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Fargion 2009 集束现象导致短暴显示为SGR

主要内容:
列举了一系列标准模型的puzzle (值得一看)
认为GRB-XRF-SGR都是由于极端集束的喷流+章动显示的不同表现. (认为张角在10^-8 sr)

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Title:		Beaming Selection and SN-GRB-Jets Evolution
Authors:		Fargion, D.; D'Armiento, D.
Publication:		eprint arXiv:0902.3293
Publication Date:		02/2009
Origin:		ARXIV
Keywords:		Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Cosmology and Extragalactic Astrophysics
Comment:		8 pages, 10 figures; white pages 2009
Bibliographic Code:		2009arXiv0902.3293F

Abstract

After a decade of Fireball reign there is a hope for thin collimated Jet to solve the Supernova-GRB mystery

Stamatikos 2009 GRB 观测仪器小综述

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Title:		Multi-Messenger Astronomy with GRBs: A White Paper for the Astro2010 Decadal Survey
Authors:		Stamatikos, Michael; Gehrels, Neil; Halzen, Francis; Meszaros, Peter; Roming, Peter W. A.
Publication:		eprint arXiv:0902.3022
Publication Date:		02/2009
Origin:		ARXIV
Keywords:		Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Cosmology and Extra-Galactic Astrophysics
Comment:		6 pages. Contributed to the Stars and Stellar Evolution (SSE) Science Frontier Panel (SFP) of the Astro2010 Decadal Survey
Bibliographic Code:		2009arXiv0902.3022S

Abstract

Gamma-ray Bursts (GRBs) are relativistic cosmological beacons of transient high energy radiation whose afterglows span the electromagnetic spectrum. Theoretical expectations of correlated neutrino and/or gravitational wave (GW) emission position GRBs at an astrophysical nexus for a metamorphosis in our understanding of the Cosmos. This new dawn in the era of experimental (particle) astrophysics and cosmology is afforded by current and planned facilities enabling the novel astronomies of high energy neutrinos and gravitational waves, in concert with unprecedented electromagnetic coverage. In this white paper, we motivate GRBs as a compelling scientific theme and highlight key technical advances that may facilitate fundamental breakthroughs in the context of Swift, Fermi, IceCube and LIGO (Laser Interferometer Gravitational Wave Observatory), whose capabilities would be augmented with JANUS (Joint Astrophysics Nascent Universe Satellite), EXIST (Energetic X-ray Imaging Survey Telescope) and LISA (Laser Interferometer Space Antenna). Scientific synergy will be achieved by leveraging the combined sensitivity of contemporaneous ground-based and satellite observatories, thus optimizing their collective discovery potential for: (i) revealing the origin(s) and acceleration mechanism(s) of cosmic rays, (ii) exposing GRB progenitor(s) and (iii) exploring the high-z Cosmos. Hence, the advent of GRB multi-messenger astronomy may cement an explicit connection to fundamental physics, via nascent cosmic windows, throughout the next decade and beyond.

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Komissarov 2009 BZ机制产生喷流

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Title:		Activation of the Blandford-Znajek mechanism in collapsing stars
Authors:		Komissarov, S. S.; Barkov, M. V.
Publication:		eprint arXiv:0902.2881
Publication Date:		02/2009
Origin:		ARXIV
Keywords:		Astrophysics - High Energy Astrophysical Phenomena
Comment:		submitted to MNRAS
Bibliographic Code:		2009arXiv0902.2881K

Abstract

Collapse of massive stars may result in formation of accreting black holes in their interior. The accreting stellar matter may advect substantial magnetic flux onto the black hole and promote release of its rotational energy via magnetic stresses (the Blandford-Znajek mechanism). In this paper we explore whether this process can explain the stellar explosions and relativistic jets associated with long Gamma-ray-bursts. In particularly, we show that the Blandford-Znajek mechanism is activated when the rest mass-energy density of matter drops below the energy density of magnetic field in the very vicinity of the black hole (within its ergosphere). We also discuss whether such a strongmagnetic field is in conflict with the rapid rotation of stellar core required in the collapsar model and suggest that the conflict can be avoided if the progenitor star is a component of close binary. In this case the stellar rotation can be sustained via spin-orbital interaction. In an alternative scenario the magnetic field is generated in the accretion disk but in this case the magnetic flux through the black hole ergosphere is not expected to be sufficiently high to explain the energetics of hypernovae by the BZ mechanism alone. However, this energy deficit can be recovered via additional power provided by the disk.

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Fiziev 2009 一个简单的旋转致密天体产生GRB jet的模型

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Title:		Toward a New Model of the Central Engine of GRB
Authors:		Fiziev, P. P.; Staicova, D. R.
Publication:		eprint arXiv:0902.2411
Publication Date:		02/2009
Origin:		ARXIV
Keywords:		Astrophysics - High Energy Astrophysical Phenomena
Comment:		7 pages, 1 figure, based on a talk given at the Fourth Aegean Summer School, 17-22 September 2007, Lesvos, Greece
Bibliographic Code:		2009arXiv0902.2411F

Abstract

We present new developments of the simple model of the central engine of GRB, proposed recently. The model is based on minimal assumptions: some rotating compact relativistic object at the center and stable perturbations of its rotating gravitational field, described by Teukolsky Master Equation. We show that using nonstandard polynomial solutions to the angular Teukolsky equation we can describe the formation of collimated jets of various forms. Appearance of imaginary part of the superradiance-like frequency is established for the first time for pure vacuum black hole jet solutions of Teukolsky equation.

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Title:		A new model of the Central Engine of GRB and the Cosmic Jets
Authors:		Fiziev, P. P.; Staicova, D. R.
Publication:		eprint arXiv:0902.2408
Publication Date:		02/2009
Origin:		ARXIV
Keywords:		Astrophysics - High Energy Astrophysical Phenomena
Comment:		6 pages, 1 figures, Based on talk given at The Advanced Workshop on Gravity, Astrophysics and Strings, GAS@BS07, 10-16.06.2007, Primorsko, Bulgaria
Bibliographic Code:		2009arXiv0902.2408F

Abstract

Despite all the already existing observational data, current models still cannot explain completely the excessive energy output and the time variability of GRB. One of the reasons for this is the lack of a good model of the central engine of GRB. A major problem in the proposed models with a black hole (BH) in the center is that they don't explain the observed evidences of late time activity of the central engine. In this paper we are starting the search for a possible model of that central engine as a rotating compact body of still unknown nature. The formation of jets in the new model lies entirely on the fundamental Teukolsky Master Equation. We demonstrate that this general model can describe the formation of collimated GRB-jets of various forms. Some preliminary results are presented.

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Xue 2009 用早期X射线定初始Lorentz factor

主要内容:
假设第一个突起是外激波产生的

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Title:		The initial Lorentz factors of fireballs inferred from the early X-ray data of SWIFT GRBs
Authors:		Xue, Rongrong; Fan, Yizhong; Wei, Daming
Publication:		eprint arXiv:0902.2613
Publication Date:		02/2009
Origin:		ARXIV
Keywords:		Astrophysics - High Energy Astrophysical Phenomena
Comment:		6 pages,1 figure,3 tables,accepted for publication in Astronomy & Astrophysics
Bibliographic Code:		2009arXiv0902.2613X

Abstract

We intend to determine the type of circumburst medium and measure directly the initial Lorentz factor $\Gamma_0$ of GRB outflows. If the early X-ray afterglow lightcurve has a peak and the whole profile across the peak is consistent with the standard external shock model, the early rise profile of light curves can be used to differentiate whether the burst was born in interstellar medium (ISM) or in stellar wind. In the thin shell case, related to a sub-relativistic reverse shock, the peak time occurring after the end of the prompt emission, can be used to derive an accurate $\Gamma_0$, especially for the ISM case. The afterglow lightcurves for a flat electron spectrum $p ~ (1,2)$ have been derived analytically. In our GRB sample, we obtain $\Gamma_0 \sim 300$ for the bursts born in ISM. We did not find any good case for bursts born in stellar wind and behaving as a thin shell that can be used to constrain $\Gamma_0$ reliably.

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Qin 2009 曲率效应导致的谱E_p在pulse上的变化

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Title:		Development of the spectrum of gamma-ray burst pulses influenced by the intrinsic spectral evolution and the curvature effect
Authors:		Qin, Y. -P.
Publication:		eprint arXiv:0902.2733
Publication Date:		02/2009
Origin:		ARXIV
Keywords:		Astrophysics - High Energy Astrophysical Phenomena
Comment:		39 pages, 15 figures, accepted by Chinese Physics B; Chinese Physics B 18 (2009) 825-844
Bibliographic Code:		2009arXiv0902.2733Q

Abstract

Spectral evolution of gamma-ray burst pulses assumed to arise from emission of fireballs is explored. It is found that, due to the curvature effect, the integrated flux and peak energy are well related by a power law in the decaying phase of pulses, where the index is about 3, being free of the intrinsic emission and the Lorentz factor. The spectrum of a pulse in its decaying phase differs slightly for different intrinsic spectral evolution patterns, indicating that it is dominated by the curvature effect. In the rising phase, the integrated flux keeps increasing whilst the peak energy remains unchanged when the intrinsic emission bears an unchanged spectrum. Within this phase, the flux decreases with the increasing of the peak energy for a hard-to-soft intrinsic spectrum, and for a soft-to-hard-to-soft intrinsic spectrum, the flux generally increases with the increasing of the peak energy. An intrinsic soft-to-hard-to-soft spectral evolution within a co-moving pulse would give rise to a pulse-like evolutionary curve for the peak energy.

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Zhang 2009 长时间余辉数值模拟

主要内容:
模拟到了１５０年以后。 主要结论：侧向膨胀不重要，来自与喷流的边缘被看到，并且下降很陡。从BM (relativistic self similar solution)到Sedov Tylor (Newtonian self similar solution)的中间过程很长。

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Title:		The Dynamics and Afterglow Radiation of Gamma-Ray Bursts: A Numerical Approach
Authors:		Zhang, Weiqun; MacFadyen, Andrew
Publication:		eprint arXiv:0902.2396
Publication Date:		02/2009
Origin:		ARXIV
Keywords:		Astrophysics - High Energy Astrophysical Phenomena
Comment:		submitted to ApJ, high-resolution version available at http://cosmo.nyu.edu/~wqzhang/publications/ag.pdf, movies of the simulation available at http://cosmo.nyu.edu/~wqzhang/movies/
Bibliographic Code:		2009arXiv0902.2396Z

Abstract

Direct multi-dimensional numerical simulation is the most reliable approach for calculating the fluid dynamics and observational signatures of relativistic jets in gamma-ray bursts (GRBs). We present a two-dimensional relativistic hydrodynamic simulation of a GRB outflow during the afterglow phase, which uses the fifth-order weighted essentially non-oscillatory scheme and adaptive mesh refinement. Initially, the jet has a Lorentz factor of 20. We have followed its evolution up to 150 years. Using the hydrodynamic data, we calculate synchrotron radiation based upon standard afterglow models and compare our results with previous analytic work. We find that the sideways expansion of a relativistic GRB jet is a very slow process and previous analytic works have overestimated its rate. In our computed lightcurves, a very sharp jet break is seen and the post-break lightcurves are steeper than analytic predictions. We find that the jet break in GRB afterglow lightcurves is mainly caused by the missing flux when the edge of the jet is observed. The outflow becomes nonrelativistic at the end of the Blandford-McKee phase. But it is still highly nonspherical, and it takes a rather long time for it to become a spherical Sedov-von Neumann-Taylor blast wave. We find that the late-time afterglows become increasingly flatter over time. But we disagree with the common notion that there is a sudden flattening in lightcurves due to the transition into the Sedov-von Neumann-Taylor solution. We have also found that there is a bump in lightcurves at very late times ($\sim 1000$ days) due to radiation from the counter jet. We speculate that such a counter jet bump might have already been observed in GRB 980703.

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