伽玛暴(Gamma-Ray Burst)笔记。记录有关伽玛暴的新文章,另外也包括看的老文章、自己的想法、以及跟天文相关的一些东西。 Feel free to leave me a message by comments or by email.

星期四, 二月 09, 2012

Puccetti, S. 2011 对有GRB的地方进行XRT的X射线巡天

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Title:
The Swift serendipitous survey in deep XRT GRB fields (SwiftFT). I. The X-ray catalog and number counts
Authors:
Puccetti, S.; Capalbi, M.; Giommi, P.; Perri, M.; Stratta, G.; Angelini, L.; Burrows, D. N.; Campana, S.;Chincarini, G.; Cusumano, G.; Gehrels, N.; Moretti, A.; Nousek, J.; Osborne, J. P.; Tagliaferri, G.
Affiliation:
AA(ASI Science Data Center, via Galileo Galilei, 00044, Frascati, Italy puccetti@asdc.asi.it), AB(ASI Science Data Center, via Galileo Galilei, 00044, Frascati, Italy), AC(ASI Science Data Center, via Galileo Galilei, 00044, Frascati, Italy), AD(ASI Science Data Center, via Galileo Galilei, 00044, Frascati, Italy), AE(ASI Science Data Center, via Galileo Galilei, 00044, Frascati, Italy), AF(NASA/Goddard Space Flight Center, Greenbelt, MD, USA), AG(Department of Astronomy and Astrophysics, Pennsylvania State University, 525 Davey Lab, University Park, PA, 16802, USA), AH(INAF, Osservatorio Astronomico di Brera, via E. Bianchi 46, 23807, Merate (LC), Italy), AI(INAF, Osservatorio Astronomico di Brera, via E. Bianchi 46, 23807, Merate (LC), Italy; Università degli Studi di Milano-Bicocca, Dipartimento di Fisica, Piazza delle Scienze 3, 20126, Milano, Italy), AJ(INAF, Istituto di Astrofisica Spaziale e Fisica Cosmica di Palermo, via U. La Malfa 153, 90146, Palermo, Italy), AK(NASA/Goddard Space Flight Center, Greenbelt, MD, USA), AL(INAF, Osservatorio Astronomico di Brera, via E. Bianchi 46, 23807, Merate (LC), Italy), AM(Department of Astronomy and Astrophysics, Pennsylvania State University, 525 Davey Lab, University Park, PA, 16802, USA), AN(Department of Physics and Astronomy, University of Leicester, Leicester, LE1 7RH, UK), AO(INAF, Osservatorio Astronomico di Brera, via E. Bianchi 46, 23807, Merate (LC), Italy)
Publication:
Astronomy & Astrophysics, Volume 528, id.A122 (A&A Homepage)
Publication Date:
04/2011
Origin:
EDP Sciences
Astronomy Keywords:
X-rays: general, surveys, catalogs, galaxies: active
DOI:
10.1051/0004-6361/201015560
Bibliographic Code:
2011A&A...528A.122P

Abstract


Aims: An accurate census of the active galactic nuclei (AGN) is a key step in investigating the nature of the correlation between the growth and evolution of super massive black holes and galaxy evolution. X-ray surveys provide one of the most efficient ways of selecting AGN. 
Methods: We searched for X-ray serendipitous sources in over 370 Swift-XRT fields centered on gamma ray bursts detected between 2004 and 2008 and observed with total exposures ranging from 10 ks to over 1 Ms. This defines the Swift Serendipitous Survey in deep XRT GRB fields, which is quite broad compared to existing surveys (~33 square degrees) and medium depth, with a faintest flux limit of 7.2 × 10-16 erg cm-2s-1 in the 0.5 to 2 keV energy range (4.8 × 10-15 erg cm-2 s-1 at 50% completeness). The survey has a high degree of uniformity thanks to the stable point spread function and small vignetting correction factors of the XRT, moreover is completely random on the sky as GRBs explode in totally unrelated parts of the sky. 
Results: In this paper we present the sample and the X-ray number counts of the high Galactic-latitude sample, estimated with high statistics over a wide flux range (i.e., 7.2 × 10-16 ÷ ~ 5 × 10-13 erg cm-2 s-1 in the 0.5-2 keV band and 3.4 × 10-15 ÷ ~ 6 × 10-13 erg cm-2 s-1 in the 2-10 keV band). We detect 9387 point-like sources with a detection Poisson probability threshold of ≤ 2 × 10-5, in at least one of the three energy bands considered (i.e. 0.3-3 keV, 2-10 keV, and 0.3-10 keV), for the total sample, while 7071 point-like sources are found at high Galactic-latitudes (i.e. |b| ≥ 20 deg). The large number of detected sources resulting from the combination of large area and deep flux limits make this survey a new important tool for investigating the evolution of AGN. In particular, the large area permits finding rare high-luminosity objects like QSO2, which are poorly sampled by other surveys, adding precious information for the luminosity function bright end. The high Galactic-latitude log N-log S relation is well determined over all the flux coverage, and it is nicely consistent with previous results at 1σ confidence level. By the hard X-ray color analysis, we find that the Swift Serendipitous Survey in deep XRT GRB fields samples relatively unobscured and mildly obscured AGN, with a fraction of obscured sources of ~37% (~15%) in the 2-10 (0.3-3 keV) band.
The survey's acronym remembers the satellite Swift and Francesca Tamburelli (FT), who contributed in a crucial way to the development of the Swift-XRT data reduction software. We dedicate this work to her memory.The full Catalog is only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/528/A122

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Dokuchaev, V. I. 2011 估算短暴几年前可能有超新星的可能

主要内容:
说每300个短暴里边能在短于2年的时间看到一个超新星“前兆”。

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Title:
Supernovae-optical precursors of short gamma-ray bursts
Authors:
Dokuchaev, V. I.; Eroshenko, Yu. N.
Affiliation:
AA(Institute for Nuclear Research, Russian Academy of Sciences), AB(Institute for Nuclear Research, Russian Academy of Sciences)
Publication:
Astronomy Letters, Volume 37, Issue 2, pp.83-90 (AstL Homepage)
Publication Date:
02/2011
Origin:
SPRINGER
Keywords:
gamma-ray bursts, neutron stars, black holes, supernovae
Abstract Copyright:
(c) 2011: Pleiades Publishing, Ltd.
DOI:
10.1134/S1063773710120035
Bibliographic Code:
2011AstL...37...83D

Abstract

The probability of observing “supernova-gamma-ray burst” (GRB) pair events and recurrent GRBs from one galaxy in a time interval of several years has been estimated. Supernova explosions in binary systems accompanied by the formation of a short-lived pair of compact objects can be the sources of such events. If a short GRB is generated during the collision of a pair, then approximately each of ˜300 short GRBs with redshift z must have an optical precursor—a supernova in the observer’s time interval <2(1 + z) yr. If the supernova explosion has the pattern of a hypernova, then a successive observation of long and short GRBs is possible. The scenario for the generation of multiple GRBs in collapsing galactic nuclei is also discussed.
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van Eerten, Hendrik J. 2011 拟合短暴的余辉光变

主要内容:
他们用数值计算模拟了狂多的长暴短暴的各种辐射。
见:
http://cosmo.nyu.edu/afterglowlibrary/

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Title:
Synthetic Off-axis Light Curves for Low-energy Gamma-Ray Bursts
Authors:
van Eerten, Hendrik J.; MacFadyen, Andrew I.
Affiliation:
AA(Center for Cosmology and Particle Physics, Physics Department, New York University, New York, NY 10003, USA), AB(Center for Cosmology and Particle Physics, Physics Department, New York University, New York, NY 10003, USA)
Publication:
The Astrophysical Journal Letters, Volume 733, Issue 2, article id. L37 (2011). (ApJL Homepage)
Publication Date:
06/2011
Origin:
IOP
Astronomy Keywords:
acceleration of particles, gamma-ray burst: general, hydrodynamics, methods: numerical
DOI:
10.1088/2041-8205/733/2/L37
Bibliographic Code:
2011ApJ...733L..37V

Abstract

We present results for a large number of gamma-ray burst (GRB) afterglow light curve calculations, done by combining high-resolution two-dimensional relativistic hydrodynamics simulations using RAM with a synchrotron radiation code. Results were obtained for jet energies, circumburst medium densities, and jet angles typical for short and underluminous GRBs, different observer angles, and observer frequencies from low radio (75 MHz) to X-ray (1.5 keV). We summarize the light curves through smooth power-law fits with up to three breaks, covering jet breaks for small observer angles, the rising phase for large observer angles, and the rise and decay of the counterjet. All light curve data are publicly available on the Web. The data can be used for model fits to observational data and as an aid for predicting observations by future telescopes such as LOFAR or the Square Kilometer Array and will benefit the study of neutron star mergers using different channels, such as gravitational-wave observations with LIGO or Virgo. For small observer angles, we find jet break times that vary significantly between frequencies, with the break time in the radio substantially postponed. Increasing the observer angle also postpones the measured jet break time. The rising phase of the light curve for large observer angle has a complex shape that cannot always be summarized by a simple power law. Except for very large observer angles, the counterjet is a distinct feature in the light curve, although in practice the signal will be exceedingly difficult to observe by then.
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Larsson, J. 2011 GRB 061007的热谱成分

主要内容:
这个暴用热谱拟合和用Band谱拟合一样好。

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Title:
Spectral components in the bright, long GRB 061007: properties of the photosphere and the nature of the outflow
Authors:
Larsson, J.; Ryde, F.; Lundman, C.; McGlynn, S.; Larsson, S.;
Affiliation:
AA(Department of Astronomy, Stockholm University,
Publication:
Monthly Notices of the Royal Astronomical Society, Volume 414, Issue 3, pp. 2642-2649. (MNRAS Homepage)
Publication Date:
07/2011
Origin:
WILEY
Astronomy Keywords:
radiation mechanisms: general, gamma-ray burst: individual: GRB 061007
Abstract Copyright:
© 2011 The Authors Monthly Notices of the Royal Astronomical Society © 2011 RAS
DOI:
10.1111/j.1365-2966.2011.18582.x
Bibliographic Code:
2011MNRAS.414.2642L

Abstract

We present a time-resolved spectral analysis of the bright, long GRB 061007 (z= 1.261) using Swift and Suzaku data. We find that the prompt emission of the burst can be equally well explained by a photospheric component together with a power law as by a Band function, and we explore the implications of the former model. The photospheric component, which we model with a multicolour blackbody, dominates the spectra and has a very stable shape throughout the burst. This component provides a natural explanation for the hardness-intensity correlation seen within the burst and also allows us to estimate the bulk Lorentz factor and the radius of the photosphere. The power-law component dominates the fit at high energies and has a nearly constant slope of -1.5. We discuss the possibility that this component is of the same origin as the high-energy power laws recently observed in some Fermi bursts.
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Ryde, Felix 2011 伽马暴光球层的辐射的贡献

主要内容:
认为光球辐射对非热成分的贡献也很大。

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Title:
Observational evidence of dissipative photospheres in gamma-ray bursts
Authors:
Ryde, Felix; Pe'Er, Asaf; Nymark, Tanja; Axelsson, Magnus; ...
Affiliation:
AA(Department of Physics, Royal Institute of Technology
Publication:
Monthly Notices of the Royal Astronomical Society, Volume 415, Issue 4, pp. 3693-3705. (MNRAS Homepage)
Publication Date:
08/2011
Origin:
WILEY
Astronomy Keywords:
radiation mechanisms: thermal, gamma-ray burst: general
Abstract Copyright:
© 2011 The Authors Monthly Notices of the Royal Astronomical Society © 2011 RAS
DOI:
10.1111/j.1365-2966.2011.18985.x
Bibliographic Code:
2011MNRAS.415.3693R

Abstract

The emission from a gamma-ray burst (GRB) photosphere can give rise to a variety of spectral shapes. The spectrum can retain the shape of a Planck function or it can be broadened and have the shape of a Band function. This fact is best illustrated by studying GRB090902B. The main gamma-ray spectral component is initially close to a Planck function, which can only be explained by emission from the jet photosphere. Later, the same component evolves into a broader Band function. This burst thus provides observational evidence that the photosphere can give rise to a non-thermal spectrum. We show that such a broadening is most naturally explained by subphotospheric dissipation in the jet. The broadening mainly depends on the strength and location of the dissipation, the magnetic field strength and the relation between the energy densities of thermal photons and electrons. We suggest that the evolution in spectral shape observed in GRB090902B is due to a decrease in the bulk Lorentz factor of the flow, leading to the main dissipation becoming subphotospheric. Such a change in the flow parameters can also explain the correlation observed between the peak energy of the spectrum and low-energy power-law slope, α, a correlation commonly observed in GRBs. We conclude that photospheric emission could indeed be a ubiquitous feature during the prompt phase in GRBs and play a decisive role in creating the diverse spectral shapes and spectral evolutions that are observed.
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Beniamini, P. 2011 通过假设GeV和MeV光子的比例,来限制GeV的流量

主要内容:
通过假设GeV的能量是MeV的0.1,Le T., & Dermer C. D., 2009, ApJ, 700, 1026.他们得到过GeV的流量,不过和观测有些不符。

他们应该是用一个更加复杂一点的办法(没看明白,但大意应该是和上面类似),得到GeV辐射的上限,也就是给出二者比例的上限。这个上限还可以和观测到了GeV流量的暴比较,见下图,红色部分,都还吻合呢。

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Title:
Limits on the GeV Emission from Gamma-Ray Bursts
Authors:
Beniamini, P.; Guetta, D.; Nakar, E.; Piran, T.
Publication:
eprint arXiv:1103.0745
Publication Date:
03/2011
Origin:
ARXIV
Keywords:
Astrophysics - High Energy Astrophysical Phenomena
Comment:
Accepted for publication in MNRAS
Bibliographic Code:
2011arXiv1103.0745N

Abstract

The Large Area Telescope (LAT) on board of the Fermi satellite detected emission above 30 MeV only in a small fraction of the long gamma-ray bursts (GRBs) detected by the Fermi Gamma-ray Burst Monitor (GBM) at 8 keV - 10 MeV. Those bursts that were detected by the LAT were among the brightest GBM bursts. We examine a sample of the most luminous GBM bursts with no LAT detection and obtain upper limits on their high energy fluence. We find an average upper limit of LAT/GBM fluence ratio of 0.13 for GeV fluence during $T_{90}$ and an average upper limit ratio of 0.45 for GeV fluence during the first 600 seconds after the trigger. These ratios strongly constrain various emission models and in particular rule out SSC models for the prompt emission. In about a third of both LAT detected and LAT non-detected bursts, we find that the extrapolation of the MeV range Band spectrum to the GeV range is larger than the observed GeV fluence (or its upper limit). While this excess is not highly significant for any specific burst, the overall excess in a large fraction of the bursts suggests a decline in the high energy spectral slope in at least some of these bursts. Possibly an evidence for the long sought after pair creation limit.
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Giovanna Dainotti, Maria 2011 暴本身光度和余辉光度的统计关系

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说这个的Spearman系数达到了0.95



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Title:
Toward a standard Gamma Ray Burst: tight correlations between the prompt and the afterglow plateau phase emission
Authors:
Giovanna Dainotti, Maria; Ostrowski, Michal; Willingale, Richard
Publication:
eprint arXiv:1103.1138
Publication Date:
03/2011
Origin:
ARXIV
Keywords:
Astrophysics - High Energy Astrophysical Phenomena
Comment:
The Data Table will appear after the paper will be accepted
Bibliographic Code:
2011arXiv1103.1138G

Abstract

To reveal and understand astrophysical processes responsible for the Gamma Ray Burst (GRB) phenomenon, it is crucial to discover and understand relations between their observational properties. The presented study is performed in the GRB rest frames and it uses a sample of 62 long GRBs from our sample of 77 Swift GRBs with known redshifts. Following the earlier analysis of the afterglow {\it characteristic luminosity $L^*_a$ -- break time $T^*_a$} correlation for a sample of long GRBs \citep{Dainotti2010} we extend it to correlations between the afterglow and the prompt emission GRB physical parameters. We reveal a tight physical scaling between the mentioned afterglow luminosity $ L^*_a$ and the prompt emission {\it mean} luminosity $<L^*_p>_{45} \equiv E_{iso}/T^*_{45}$. The distribution, with the Spearman correlation coefficient reaching 0.95 for the data subsample with most regular light curves, can be fitted with approximately $L^*_a \propto {<L^*_p>_{45}}^{0.7}$. We also analyzed correlations of $L^*_a$ with several other prompt emission parameters, including the isotropic energy $E_{iso}$, the peak energy in the $\nu F_{\nu}$ spectrum, $E_{peak}$, and the variability parameter, $V$, defined by \cite{N000}. As a result, we reveal significant correlations also between these quantities, with an exception of the variability parameter. The main result of the present study is the discovery that the highest correlated GRB subsample in the \citet{Dainotti2010} afterglow analysis, for the GRBs with canonical X\,-\,ray light curves, leads also to the highest {\it prompt-afterglow} correlations and such events can be considered to form a sample of standard GRBs for astrophysics and cosmology.
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