Atwood 2013 对LAT高能辐射光子的重新分析

主要内容:
由于更新了光子重建的程序，导致伽马暴的LAT光子也要重新分析。
看来最可靠的LAT的结果得等他们的最终catalog了，鬼知道什么时候他们又重新reconstruction一把。

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Title:		New Fermi-LAT Event Reconstruction Reveals More High-energy Gamma Rays from Gamma-Ray Bursts
Authors:		Atwood, W. B.; Baldini, L.; Bregeon, J.; Bruel, P.; Chekhtman, A.; Cohen-Tanugi, J.; Drlica-Wagner, A.; Granot, J.; Longo, F.; Omodei, N.; Pesce-Rollins, M.; Razzaque, S.; Rochester, L. S.; Sgrò, C.; Tinivella, M.; Usher, T. L.; Zimmer, S.
Affiliation:		AA(Santa Cruz Institute for Particle Physics, Department of Physics and Department of Astronomy and Astrophysics, University of California at Santa Cruz, Santa Cruz, CA 95064, USA melissa.pesce.rollins@pi.infn.it), ...
Publication:		The Astrophysical Journal, Volume 774, Issue 1, article id. 76, 6 pp. (2013). (ApJ Homepage)
Publication Date:		09/2013
Origin:		IOP
Astronomy Keywords:		astroparticle physics, cosmology: observations, gamma rays: general, methods: data analysis
DOI:		10.1088/0004-637X/774/1/76
Bibliographic Code:		2013ApJ...774...76A

Abstract

Based on the experience gained during the four and a half years of the mission, the Fermi-LAT Collaboration has undertaken a comprehensive revision of the event-level analysis going under the name of Pass 8. Although it is not yet finalized, we can test the improvements in the new event reconstruction with the special case of the prompt phase of bright gamma-ray bursts (GRBs), where the signal-to-noise ratio is large enough that loose selection cuts are sufficient to identify gamma rays associated with the source. Using the new event reconstruction, we have re-analyzed 10 GRBs previously detected by the Large Area Telescope (LAT) for which an X-ray/optical follow-up was possible and found four new gamma rays with energies greater than 10 GeV in addition to the seven previously known. Among these four is a 27.4 GeV gamma ray from GRB 080916C, which has a redshift of 4.35, thus making it the gamma ray with the highest intrinsic energy (~147 GeV) detected from a GRB. We present here the salient aspects of the new event reconstruction and discuss the scientific implications of these new high-energy gamma rays, such as constraining extragalactic background light models, Lorentz invariance violation tests, the prompt emission mechanism, and the bulk Lorentz factor of the emitting region.

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Beloborodov 2013 GeV辐射的来源：星风环境下的外康普顿散射

主要内容:
种子光子是瞬时辐射的MeV光子。

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Title:		On the origin of GeV emission in gamma-ray bursts
Authors:		Beloborodov, Andrei M.; Hascoet, Romain; Vurm, Indrek
Publication:		eprint arXiv:1307.2663
Publication Date:		07/2013
Origin:		ARXIV
Keywords:		Astrophysics - High Energy Astrophysical Phenomena
Comment:		20 pages, 9 figures, accepted to ApJ
Bibliographic Code:		2013arXiv1307.2663B

Abstract

The most common progenitors of gamma-ray bursts (GRBs) are massive stars with strong stellar winds. We show that the GRB blast wave in the wind should emit a bright GeV flash. It is produced by inverse Compton cooling of the thermal plasma behind the forward shock wave. The main part of the flash is shaped by scattering of the prompt MeV radiation (emitted at smaller radii) which streams through the external blast wave. The inverse-Compton flash is bright due to the huge e+- enrichment of the external medium. At late times, the blast wave switches to normal synchrotron-self-Compton cooling. The mechanism is demonstrated by a detailed transfer simulation. The observed prompt MeV radiation is taken as an input of the simulation; we use GRB 080916C as an example. The result reproduces the GeV flash observed by the Fermi telescope. It explains the delayed onset, the steep rise, the peak flux, the time of the peak, the long smooth decline, and the spectral slope of GeV emission. The wind density required to reproduce all these features is typical of Wolf-Rayet stars. Our simulation predicts strong TeV emission 1 min after the burst trigger; then a cutoff in the observed high-energy spectrum is expected from absorption by extragalactic background light. In addition, a bright optical counterpart of the GeV flash is predicted for plausible values of the magnetic field; such a double (optical+GeV) flash has been observed in GRB 130427A.

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Panaitescu 2013 LAT光变中光子光子碰撞的光深影响

主要内容:
首先高能光子可能会和低能光子碰撞，其实产生的正负电子对会对光深有贡献。

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Title:		The effect of photon-photon absorption on Fermi-LAT light-curves of GRB afterglows
Authors:		Panaitescu, A.; Vestrand, W. T.; Wozniak, P.
Publication:		eprint arXiv:1308.3197
Publication Date:		08/2013
Origin:		ARXIV
Keywords:		Astrophysics - High Energy Astrophysical Phenomena
Comment:		8 pages, submitted to MNRAS 13 May 2013
Bibliographic Code:		2013arXiv1308.3197P

Abstract

We investigate the effect that the absorption of high-energy (above 100 MeV) photons produced in GRB afterglow shocks has on the light-curves and spectra of Fermi-LAT afterglows. Afterglows produced by the interaction of a relativistic outflow with a wind-like medium peak when the blast-wave deceleration sets in, and the afterglow spectrum could be hardening before that peak, as the optical thickness to pair-formation is decreasing. In contrast, in afterglows produced in the interaction with a homogeneous medium, the optical thickness to pair-formation should increase and yield a light-curve peak when it reaches unity, followed by a fast light-curve decay, accompanied by a spectral softening. If energy is injected in the blast-wave, then the accelerated increase of the optical thickness yields a convex afterglow light-curve. Other features, such as a double-peak light-curve or a broad hump, can arise from the evolution of the optical thickness to photon-photon absorption. Fast decays and convex light-curves are seen in a few LAT afterglows, but the expected spectral softening is rarely seen in (and difficult to measure with) LAT observations. Furthermore, for the effects of photon-photon attenuation to shape the high-energy afterglow light-curve without attenuating it too much, the ejecta initial Lorentz factor must be in a relatively narrow range (50--200), which reduces the chance of observing those effects.

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Wang, K. 2013 X-ray耀发阶段的GeV辐射

主要内容:
晚期内积波产生的X射线被外激波逆康普顿散射到GeV。并用到GRB 100728A上。

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Title:		GeV Emission during X-Ray Flares from Late Internal Shocks: Application to GRB 100728A
Authors:		Wang, K.; Dai, Z. G.
Affiliation:		AA(School of Astronomy and Space Science, Nanjing University, Nanjing 210093, China ; Key Laboratory of Modern Astronomy and Astrophysics (Nanjing University), Ministry of Education, China; dzg@nju.edu.cn), AB(School of Astronomy and Space Science, Nanjing University, Nanjing 210093, China ; Key Laboratory of Modern Astronomy and Astrophysics (Nanjing University), Ministry of Education, China)
Publication:		The Astrophysical Journal, Volume 772, Issue 2, article id. 152, 8 pp. (2013). (ApJ Homepage)
Publication Date:		08/2013
Origin:		IOP
Astronomy Keywords:		gamma-ray burst: general, radiation mechanisms: non-thermal
DOI:		10.1088/0004-637X/772/2/152
Bibliographic Code:		2013ApJ...772..152W

Abstract

Recently, the GeV radiation during the X-ray flare activity in GRB 100728A was detected by Fermi/LAT. Here, we study the dynamics and emission properties of a collision between two homogeneous shells based on the late internal shock model. The GeV photons can be produced from X-ray flare photons being upscattered by relativistic electrons that are accelerated by forward-reverse shocks, where the involved radiative processes include synchrotron self-Compton and crossing inverse-Compton scattering. Using analytical and numerical calculations, the observed spectral properties in GRB 100728A can be well explained.

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Ackermann 2013 Fermi-LAT都GRB 130427A高能辐射的观测

主要内容:
最高能量95GeV，持续时间20小时。

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对数时间的光变

普通时间的光变

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Title:		Fermi-LAT Observations of the Gamma-ray Burst GRB 130427A
Authors:		Fermi-LAT collaboration; Fermi-GBM collaboration
Publication:		eprint arXiv:1311.5623
Publication Date:		11/2013
Origin:		ARXIV
Keywords:		Astrophysics - High Energy Astrophysical Phenomena
Comment:		30 pages, 6 figures. Accepted for publication in Science. Corresponding authors: S. Zhu (sjzhu@umd.edu); J. Chiang (jchiang@slac.stanford.edu); C. Dermer (charles.dermer@nrl.navy.mil); N. Omodei (nicola.omodei@stanford.edu); G. Vianello (giacomov@slac.stanford.edu); S. Xiong (Shaolin.Xiong@uah.edu); doi:10.1126/science.1242353
Bibliographic Code:		2013arXiv1311.5623Z

Abstract

The observations of the exceptionally bright gamma-ray burst (GRB) 130427A by the Large Area Telescope aboard the Fermi Gamma-ray Space Telescope provide constraints on the nature of such unique astrophysical sources. GRB 130427A had the largest fluence, highest-energy photon (95 GeV), longest $\gamma$-ray duration (20 hours), and one of the largest isotropic energy releases ever observed from a GRB. Temporal and spectral analyses of GRB 130427A challenge the widely accepted model that the non-thermal high-energy emission in the afterglow phase of GRBs is synchrotron emission radiated by electrons accelerated at an external shock.

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Veres 2013 能量注入所产生的GeV，TeV辐射

主要内容:
考虑能量注入到反向激波中，或者外激波中，所产生的同步辐射和逆康普顿散射的高能成分。（不知道这里为什么只针对短暴）

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Title:		Prospects for GeV-TeV detection of short gamma-ray bursts with extended emission
Authors:		Veres, P.; Mészáros, P.
Publication:		eprint arXiv:1312.0590
Publication Date:		12/2013
Origin:		ARXIV
Keywords:		Astrophysics - High Energy Astrophysical Phenomena
Comment:		8 pages, 15 figures, submitted to ApJ
Bibliographic Code:		2013arXiv1312.0590V

Abstract

We discuss the GeV to TeV photon emission of gamma-ray bursts (GRBs) within the refreshed shock and the continuous injection scenarios, motivated by the observation of extended emission in a substantial fraction of short GRBs. In the first model we assume that the central engine emits promptly material with a range of Lorentz factors. When the fastest shell starts to decelerate, it drives a forward shock into the ambient medium and a reverse shock in the ejecta. These shocks are reenergized by the slower and later arriving material. In the second model we assume that there is a continued ejection of material over an extended time, and the continuously arriving new material keeps reenergizing the shocks formed by the preceding shells of ejecta. We calculate the synchrotron and synchrotron self-Compton radiation components for the forward and reverse shocks and find that prospective and current GeV to TeV range instruments such as CTA, HAWC, VERITAS and HESS have a good chance to detect afterglows of short bursts with extended emission, assuming a reasonable response time.

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Liu 2014 GRB 131231A的高能辐射

主要内容:
可能来自外激波的同步自康普顿。

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Title:		GRB 131231A: Implications of the hard GeV emission
Authors:		Liu, Bin; Chen, Wei; Liang, Yun-Feng; Zhou, Bei; He, Hao-Ning; Tam, Pak-Hin Thomas; Shao, Lang; Jin, Zhi-Ping; Fan, Yi-Zhong;Wei, Da-Ming
Publication:		eprint arXiv:1401.7283
Publication Date:		01/2014
Origin:		ARXIV
Keywords:		Astrophysics - High Energy Astrophysical Phenomena
Comment:		5 pages,4 figures
Bibliographic Code:		2014arXiv1401.7283L

Abstract

GRB 131231A was detected by the Large Area Telescope onboard Fermi Space Gamma-ray Telescope. The high energy gamma-ray ($> 100$ MeV) afterglow emission spectrum is as hard as $F_\nu \propto \nu^{-0.50\pm0.13}$ in the first $\sim 1300$ s after the trigger, and the most energetic photon has an energy $\sim 62$ GeV. Such a hard spectrum is at odds with the model of synchrotron radiation of the external forward shock. Instead, both its spectrum and temporal behavior are found to be consistent with the synchrotron self-Compton radiation of the forward shock-accelerated electrons. We show that the prospect for detecting GRB 131231A-like GRBs with Cherenkov Telescope Array (CTA) is quite promising, and with an exposure time of $\sim 0.5$ hour, the $25$ GeV, $40$ GeV, and $100$ GeV gamma-ray emission of such GRBs could be detected within $1$ hour, $4$ hours, and $12$ hours after the burst, respectively.

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Basak, Rupal 2013 高能GeV和MeV的幂律成分相关

主要内容:
他们把MeV的分成两种成分：黑体（双温）+幂律；然后发现幂律成分的光变和GeV瞬时阶段的光变一致（注意不是晚期的，他们还是同意晚期的还是外激波的同步辐射）(另外注意，这一点不是他们文章的主要内容，而是进一步的目标，他们发现的仅仅是：对于有很多GeV光子的暴，幂律的MeV光子和LAT的GeV光子一样，也有延迟，见下图)，以此说明瞬时阶段的辐射和瞬时阶段的幂律的MeV是同源的。

那么这么说的话，一共就有如下这些成分：瞬时的两个黑体成分，可能是来自光球辐射（为什么是两个呢？） ；瞬时幂律成分，来自内激波，这个延伸到了GeV；外激波余辉，延伸到了GeV。

于是紧接着可以做的一件事情：分析幂律MeV光子和瞬时阶段的GeV光子的光变曲线的关联程度（但是估计很难，因为不知道怎么在光变上区分幂律和非幂律的光子）。

嗯，也许把MeV的分出几个不同的成分是解释GeV以及MeV自身的一个办法。

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幂律部分的MeV光子应该和GeV的track

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Title:		A lingering non-thermal component in the GRB prompt emission: predicting GeV emission from the MeV spectrum
Authors:		Basak, Rupal; Rao, A. R.
Publication:		eprint arXiv:1308.2819
Publication Date:		08/2013
Origin:		ARXIV
Keywords:		Astrophysics - High Energy Astrophysical Phenomena
Comment:		9 Pages, 2 Figures, ApJ Accepted
Bibliographic Code:		2013arXiv1308.2819B

Abstract

The high energy GeV emission of gamma-ray bursts (GRBs), detected by \emph{Fermi}/LAT, has a significantly different morphology compared to the lower energy MeV emission, detected by \emph{Fermi}/GBM. Though the late time GeV emission is believed to be synchrotron radiation produced via an external shock, this emission as early as the prompt phase is puzzling. Meaningful connection between these two emissions can be drawn only by an accurate description of the prompt MeV spectrum. We perform a time-resolved spectroscopy of the GBM data of long GRBs having significant GeV emission, using a model consisting of 2 blackbodies and a power-law. We examine in detail the evolution of the spectral components and found that GRBs having high GeV emission (GRB 090902B and GRB 090926A) have a delayed onset of the power-law component, in the GBM spectrum, which lingers at the later part of the prompt emission. This behaviour mimics the flux evolution in LAT. In contrast, bright GBM GRBs with an order of magnitude lower GeV emission (GRB 100724B and GRB 091003) show a coupled variability of the total and the power-law flux. Further, by analyzing the data for a set of 17 GRBs, we find a strong correlation between the power-law fluence in the MeV and the LAT fluence (Pearson correlation: r=0.88 and Spearman correlation: $\rho=0.81$). We demonstrate that this correlation is not influenced by the correlation between the total and the power-law fluences at a confidence level of 2.3$\sigma$. We speculate the possible radiation mechanisms responsible for the correlation.

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Sanchez 2013 一个python写的LAT的简化数据分析软件

主要内容:
叫Enrico

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文章信息:

arXiv:1307.4534 [pdf, other]

Enrico : a Python package to simplify Fermi-LAT analysis

D.A. Sanchez, C. Deil

Comments: In Proceedings of the 33rd International Cosmic Ray Conference (ICRC2013), Rio de Janeiro (Brazil)

Subjects: High Energy Astrophysical Phenomena (astro-ph.HE); Instrumentation and Methods for Astrophysics (astro-ph.IM)

With the advent of the Large Array Telescope (LAT) on board the Fermi satellite, a new window on the Universe has been opened. Publicly available, the Fermi-LAT data come together with an analysis software named ScienceTools (ST, this http URL) which can be run through a Python interface. Nevertheless, for the user, the ST can be hard to run and imply several steps. Users already contributed with scripts for a specific task but no tool allowing a complete analysis is currently available.
We present a Python package called {\tt Enrico}, designed to facilitate the data analysis. Using only configuration files and front end tools from the command line, the user can easily perform/reproduce an entire Fermi analysis and make plots for publications. It also include new features like debug plots, pipeline execution on one or several CPUs, downloading of the Fermi data or the generation of a sky model from the Fermi catalogue.
{\tt Enrico} is an open-source project currently available for download at \url{https://github.com/gammapy/enrico}

Neil Gehrels 2012 高能暂现源--包括一些奇怪的个体

主要内容:
高能暂现源有：

其中TGF：Terrestrial γ−ray flashes， GRB：伽马暴，SGR：软伽马重复暴，TDE：Tidal disruption events，AGN：活动星系核。

比较奇怪的源有：
Short “GRB” 050925: 只有70ms，除了伽马射线，没有其他任何counterpart，也没有宿主星系。说可能是一个小的SGR的爆发（那就应该在别的时候看到其他的爆发啊，等到现在7年了，貌似没有报道吧）。

GRB 060218/SN 2006aj: 和超新星成协的软的伽马暴。





RS Oph 2006: 来自白矮星的Nova。XRT对它们的研究提供了更新的手段。


GRBs 060505 & 060614: 没有超新星成协的长暴，虽然很努力地去看了。

Hostless GRB 070125: 没有宿主星系的亮暴，虽然用Hubble看到25.4星等了。如果红移放到1.5，各向同性能量有1e54erg，相当于半个太阳质量。



Galactic “GRB” 070610: 可能是一类新的包含黑洞的X射线新星。（也就是黑洞吸积盘的增亮。）


XRO 080109 - SN 2008D: 是XRT巡天的时候看到的，出现在超新星“工厂” NGC 2770里，那里历史上（约15年）共爆发了三个超新星。不是伽马暴。


EV Lac superflare:

dMe star 的定义 -  An M-type red-dwarf star whose spectrum displays emission lines (hence the suffix ‘e’) due to hydrogen (Hα) and calcium (H and K lines). This activity indicates enhanced coronal emission (a dMe star is usually also an X-ray source) as a result of the powerful magnetic fields generated by the deep convection zone in the star.
from： http://www.galaxyzooforum.org/index.php?topic=277367.0

Pulsing GRB 090709: 在它的光变曲线里看到了8.06s的周期。见这里

 图片from： http://gcn.gsfc.nasa.gov/notices_s/356890/BA/
不过傅立叶变换分析不怎么看得出来：

GRB 101225 “Christmas burst”: 这个暴超级长，大于1700s，没看到宿主星系，不好说是啥。








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文章信息:

arXiv:1207.6346 [pdf, other]

High Energy Transients

Neil Gehrels, John K. Cannizzo

Comments: 20 pages, 12 figures; "New windows on transients across the Universe issue" Discussion Meeting issue of Philosophical Transactions A, ed. P. O'Brien, S. Smartt, R. Wijers & K. Pounds; 2012, subm

Subjects: High Energy Astrophysical Phenomena (astro-ph.HE)

We present an overview of high energy transients in astrophysics, highlighting important advances over the past 50 years. We begin with early discoveries of gamma-ray transients, and then delve into physical details associated with a variety of phenomena. We discuss some of the unexpected transients found by Fermi and Swift, many of which are not easily classifiable or in some way challenge conventional wisdom. These objects are important insofar as they underscore the necessity of future, more detailed studies.