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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