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.

星期五, 二月 07, 2014

Littlejohns 2013 低红移和高红移的暴不一样

主要内容:
通过模拟光变曲线,把低红移的移到高红移去(会包括流量的减少和能段的移动),看和实际观测到的高红移的暴的表现是否一致,用KS检验,发现不一样。

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Title:
Are gamma-ray bursts the same at high redshift and low redshift?
Authors:
Littlejohns, O. M.; Tanvir, N. R.; Willingale, R.; Evans, P. A.; O'Brien, P. T.; Levan, A. J.
Affiliation:
AA(Department of Physics and Astronomy, University of Leicester, Leicester LE1 7RH, UK; School of Earth and Space Exploration, Arizona State University, Tempe, AZ 85287, USA; olittlej@asu.edu), AB(Department of Physics and Astronomy, University of Leicester, Leicester LE1 7RH, UK), AC(Department of Physics and Astronomy, University of Leicester, Leicester LE1 7RH, UK), AD(Department of Physics and Astronomy, University of Leicester, Leicester LE1 7RH, UK), AE(Department of Physics and Astronomy, University of Leicester, Leicester LE1 7RH, UK), AF(Department of Physics, University of Warwick, Coventry CV4 7AL, UK)
Publication:
Monthly Notices of the Royal Astronomical Society, Volume 436, Issue 4, p.3640-3655 (MNRAS Homepage)
Publication Date:
12/2013
Origin:
OUP
Astronomy Keywords:
gamma-ray burst: general
Abstract Copyright:
2013 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society
DOI:
10.1093/mnras/stt1841
Bibliographic Code:
2013MNRAS.436.3640L

Abstract

The majority of Swift gamma-ray bursts (GRBs) observed at z ≳ 6 have prompt durations of T90 ≲ 30 s, which, at first sight, is surprising given that cosmological time dilation means this corresponds to ≲5 s in their rest frames. We have tested whether the high-redshift GRBs are consistent with being drawn from the same population as those observed at low redshift by comparing them to an artificially redshifted sample of 114 z < 4 bursts. This is accomplished using two methods to produce realistic high-z simulations of light curves based on the observed characteristics of the low-z sample. In Method 1 we use the Swift/Burst Alert Telescope (BAT) data directly, taking the photons detected in the harder bands to predict what would be seen in the softest energy band if the burst were seen at higher z. In Method 2 we fit the light curves with a model, and use that to extrapolate the expected behaviour over the whole BAT energy range at any redshift. Based on the results of Method 2, a Kolmogorov-Smirnov test of their durations finds a ˜1 per cent probability that the high-z GRB sample is drawn from the same population as the bright low-z sample. Although apparently marginally significant, we must bear in mind that this test was partially a posteriori, since the rest-frame short durations of several high-z bursts motivated the study in the first instance.

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