Ohno 2010 几个Fermi-LAT观测的暴

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会议文集，随便列举了几个暴的观测：GRB 080825C and GRB 090217和短暴 GRB 081024B。

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Title:		Fermi-LAT observations of GRBs with weak LAT emission
Authors:		Ohno, Masanori; for the Fermi-LAT/GBM collaborations
Publication:		eprint arXiv:1002.0228
Publication Date:		02/2010
Origin:		ARXIV
Keywords:		Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Cosmology and Extragalactic Astrophysics
Comment:		2009 Fermi Symposium. eConf Proceedings C091122
Bibliographic Code:		2010arXiv1002.0228O

Abstract

We present the analysis results of three Gamma-Ray Bursts (GRBs) detected by the Gamma-ray Burst Monitor (GBM) and the Large Area Telescope (LAT) onboard Fermi: the two long GRB 080825C and GRB 090217, and the first short burst with GeV photons GRB 081024B. The emission from GRB 081024B observed by the LAT above 100 MeV is delayed with respect to the GBM trigger, and significantly extends after the low-energy episode. Some hints for spectral hardening was observed in this burst as well as in GRB 080825C, possibly related to a separate and harder component showing up at late times. Conversely, GRB 090217 does not exhibit any noticeable feature. Together with the other bright LAT detected bursts (e.g. GRB 080916C and GRB 090510), these observations help to classify the GRB properties and give new insight on the acceleration mechanisms responsible for their emission at the highest energies.

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Kizivat 2010 伽玛暴黑洞吸积盘附近的VP过程

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Title:		Gamma-Ray Bursts Black hole accretion disks as a site for the vp-process
Authors:		Kizivat, L. -T.; Martinez-Pinedo, G.; Langanke, K.; Surman, R.; McLaughlin, G. C.
Publication:		eprint arXiv:1001.3009
Publication Date:		01/2010
Origin:		ARXIV
Keywords:		Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Solar and Stellar Astrophysics
Comment:		9 pages, 16 figures, accepted for publication in Phys. Rev. C
Bibliographic Code:		2010arXiv1001.3009K

Abstract

We study proton rich nucleosynthesis in windlike outflows from gamma-ray bursts accretion disks with the aim to determine if such outflows are a site of the vp-process. The efficacy of this vp-process depends on thermodynamic and hydrodynamic factors. We discuss the importance of the entropy of the material, the outflow rate, the initial ejection point and accretion rate of the disk. In some cases the vp-process pushes the nucleosynthesis out to A~100 and produces light p-nuclei. However, even when these nuclei are not produced, neutrino induced interactions can significantly alter the abundance pattern and cannot be neglected.

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Gorecki 2010 超高能伽玛射线与红外背景光子的作用定Hubble参数

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也可以用伽玛暴的超高能辐射的缺失来做。

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Title:		Very high energy gamma-rays and the Hubble parameter
Authors:		Gorecki, A.; Barrau, A.; Grain, J.; Memola, E.
Publication:		eprint arXiv:1001.2973
Publication Date:		01/2010
Origin:		ARXIV
Keywords:		Astrophysics - Cosmology and Extragalactic Astrophysics, Astrophysics - High Energy Astrophysical Phenomena
Comment:		Proc. of the 12th Marcel Grossmann meeting on general relativity. 3 pages, 1 figure
Bibliographic Code:		2010arXiv1001.2973G

Abstract

A new method, based on the absorption of very high-energy gamma-rays by the cosmic infrared background, is proposed to constrain the value of the Hubble constant. As this value is both fundamental for cosmology and still not very well measured, it is worth developing such alternative methods. Our lower limit at the 68% confidence level is H0 > 74 km/s/Mpc, leading, when combined with the HST results, to H0 ~ 76 km/s/Mpc. Interestingly, this value, which is significantly higher than the usually considered one, is in exact agreement with other independent approaches based on baryonic acoustic oscillations and X-ray measurements. Forthcoming data from the experiments HESS-2 and CTA should help improving those results. Finally, we briefly mention a plausible correlation between absorption by the extragalactic background light and the absence of observation of gamma-ray bursts (GRBs) at very high energies.

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Lopez-Camara 2010 在吸积盘系统中由于critical角动量导致的喷流宁静期

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Title:		Quiescence and late time activity in collapsars due to critical angular momentum distributions
Authors:		Lopez-Camara, D.
Publication:		eprint arXiv:1001.4770
Publication Date:		01/2010
Origin:		ARXIV
Keywords:		Astrophysics - High Energy Astrophysical Phenomena
Comment:		Proceedings for "The shocking Universe: Gamma-Ray Bursts and High Energy Shock Phenomena in the Universe", Venice 2009
Bibliographic Code:		2010arXiv1001.4770L

Abstract

Even thought a large amount of long gamma ray bursts (LGRBs) present quiescent periods, their origin remains unclear. In this talk, it is shown how different angular momentum distributions, as a function of the stellar radius), can lead to neutrino luminosity variability and the possibility of quiescent epochs in LGRBs.

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Raikov 2010 伽玛暴的空间分布的不均匀性

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伽玛暴的红移分布和距离分布。

和伽玛暴关联的类星体的红移分布。

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Title:		Non-homogeneities in the spatial distribution of gamma-ray bursts
Authors:		Raikov, A. A.; Orlov, V. V.; Beketov, O. B.
Publication:		eprint arXiv:1001.4592
Publication Date:		01/2010
Origin:		ARXIV
Keywords:		Astrophysics - Cosmology and Extragalactic Astrophysics
Comment:		12 pages, 8 figures
Bibliographic Code:		2010arXiv1001.4592R

Abstract

In order to reveal possible non-homogeneities in the spatial distribution of long (T_90 > 2^s) gamma-ray bursts we have examined 201 of them with known redshifts z. For different functional forms of metric distance r(z)we use the distribution function f(l)of separations between objects. Asymptotically, for small l this function behaves like f(l)~l^{D-1} for fractal sets whose fractal dimension is D. It is revealed that for all of the considered forms of r(z) the spatial distribution of gamma-ray burst sources shows signs of fractality with D=2.2-2.5. A few spatially isolated groups of gamma-ray burst sources have been found, one of which has equatorial coordinates alpha extending from 23^h 56^m to 0^h 49^m and delta from +19^o to +23^o its redshifts being within the range of 0.81 to 0.94.

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Sidoli 2010 EXIST可能对超亮快X射线变源的观测

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Supergiant Fast X-ray Transients (SFXTs) 是 High Mass X-ray Binaries involving about 20 sources to date, with 8 firmly identified SFXTs and many candidates.

the bright flares (peaking at 1E36-1E37erg/s)

EXIST是 Energetic X-ray Imaging Survey Telescope (EXIST)

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Title:		EXIST perspective for Supergiant Fast X-ray Transients
Authors:		Sidoli, L.; Sguera, V.; Bazzano, A.; Ubertini, P.
Publication:		eprint arXiv:1001.3234
Publication Date:		01/2010
Origin:		ARXIV
Keywords:		Astrophysics - Instrumentation and Methods for Astrophysics, Astrophysics - High Energy Astrophysical Phenomena
Comment:		Accepted for publication on PoS, Proceedings of "The Extreme sky: Sampling the Universe above 10 keV", held in Otranto (Italy) in October 2009
Bibliographic Code:		2010arXiv1001.3234S

Abstract

Supergiant Fast X-ray Transients (SFXTs) are one of the most intriguing (and unexpected) results of the INTEGRAL mission. They are a new class of High Mass X-ray Binaries involving about 20 sources to date, with 8 firmly identified SFXTs and many candidates. They are composed by a massive OB supergiant star as companion donor and a compact object. At least four SFXTs host a neutron star, because X-ray pulsations have been discovered, while for the others a black hole cannot be excluded. SFXTs display short X-ray outbursts (compared with Be/X-ray transients) characterized by fast flares on brief timescales of hours and large flux variability typically in the range 1,000-100,000. The INTEGRAL/IBIS sensitivity allowed to catch only the bright flares (peaking at 1E36-1E37erg/s), without persistent or quiescent emission. The investigation of their properties, in particular the rapid variability time scales of their flaring activity, will greatly benefit from observations with the Energetic X-ray Imaging Survey Telescope (EXIST), with the possibility to perform a long term and continuous as possible monitoring of the hard X-ray sky.

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Linder 2009 完全用吸积盘解释X射线余辉的快下将和平降阶段

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Title:		Collapsar Accretion and the Gamma-Ray Burst X-Ray Light Curve
Authors:		Lindner, Christopher C.; Milosavljevic, Milos; Couch, Sean M.; Kumar, Pawan
Publication:		eprint arXiv:0910.4989
Publication Date:		10/2009
Origin:		ARXIV
Keywords:		Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Solar and Stellar Astrophysics
Comment:		16 pages, 10 figures
Bibliographic Code:		2009arXiv0910.4989L

Abstract

We present axisymmetric hydrodynamical simulations of the long-term accretion of a rotating GRB progenitor star, a "collapsar," onto the central compact object. The simulations were carried out with the adaptive mesh refinement code FLASH in two spatial dimensions and with an explicit shear viscosity. The evolution of the central accretion rate exhibits phases reminiscent of the long GRB gamma-ray and X-ray light curve, which lends support to the proposal that the luminosity is modulated by the central accretion rate. After a few tens of seconds, an accretion shock sweeps outward through the star. The formation and outward expansion of the accretion shock is accompanied with a sudden and rapid power-law decline in the central accretion rate Mdot ~ t^{-2.8}, which resembles the L_X ~ t^{-3} decline observed in the X-ray light curves. The collapsed, shock-heated stellar envelope settles into a thick, low-mass equatorial disk embedded within a massive, pressure-supported atmosphere. After a few hundred seconds, the inflow of low-angular-momentum material in the axial funnel reverses into an outflow from the surface of the thick disk. Meanwhile, the rapid decline of the accretion rate slows down, or even settles a in steady state with Mdot ~ 5x10^{-5} Msun/s, which resembles the "plateau" phase in the X-ray light curve. While the duration of the "prompt" phase depends on the resolution in our simulations, we provide an analytical model taking into account neutrino losses that estimates the duration to be ~20 s. The model suggests that the steep decline in GRB X-ray light curves is triggered by the circularization of the infalling stellar envelope at radii where the virial temperature is below ~10^{10} K, such that neutrino cooling shuts off and an outward expansion of the accretion shock becomes imminent.

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Re: 测试一下用邮件发blogger加图片

再次测试. 貌似显示起来比较困难.

2009/10/27 Yuan-Chuan Zou <yuanchuan@gmail.com>

添加的时候貌似没什么问题, 就看是否能在blogger那边显示了.

测试一下用邮件发blogger加图片

添加的时候貌似没什么问题, 就看是否能在blogger那边显示了.

Xiao 2009 加权估计长暴的红移

用多种方法估计红移, 然后给每个方法一个权重, 得到加权平均值. (不觉得这样就可以得到更好的估计值) ・ Find Similar Abstracts (with default settings below)

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Title:		Estimating Redshifts for Long Gamma-Ray Bursts
Authors:		Xiao, Limin; Schaefer, Bradley E.
Publication:		eprint arXiv:0910.4945
Publication Date:		10/2009
Origin:		ARXIV
Keywords:		Astrophysics - Cosmology and Extragalactic Astrophysics
Comment:		The Astrophysical Journal accepted
Bibliographic Code:		2009arXiv0910.4945X

Abstract

We are constructing a program to estimate the redshifts for GRBs from the original Swift light curves and spectra, aiming to get redshifts for the Swift bursts \textit{without} spectroscopic or photometric redshifts. We derive the luminosity indicators from the light curves and spectra of each burst, including the lag time between low and high photon energy light curves, the variability of the light curve, the peak energy of the spectrum, the number of peaks in the light curve, and the minimum rise time of the peaks. These luminosity indicators can each be related directly to the luminosity, and we combine their independent luminosities into one weighted average. Then with our combined luminosity value, the observed burst peak brightness, and the concordance redshift-distance relation, we can derive the redshift for each burst. In this paper, we test the accuracy of our method on 107 bursts with known spectroscopic redshift. The reduced $\chi^2$ of our best redshifts ($z_{best}$) compared with known spectroscopic redshifts ($z_{spec}$) is 0.86, and the average value of $log_{10}(z_{best}/z_{spec})$ is 0.01, with this indicating that our error bars are good and our estimates are not biased. The RMS scatter of $log_{10}(z_{best}/z_{spec})$ is 0.26. For Swift bursts measured over a relatively narrow energy band, the uncertainty in determining the peak energy is one of the main restrictions on our accuracy. Although the accuracy of our $z_{best}$ values are not as good as that of spectroscopic redshifts, it is very useful for demographic studies, as our sample is nearly complete and the redshifts do not have the severe selection effects associated with optical spectroscopy.

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