Chincarini 2008 伽玛暴的耀发II

主要内容:
主要关于050904和050724的

精彩摘抄:


文章信息:

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· arXiv e-print (arXiv:0809.2151)

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Title:		Flares in Gamma Ray Bursts (II)
Authors:		Chincarini, G.; Margutti, R.; Mao, J.; Pasotti, F.; Guidorzi, C.; Covino, S.; D'avanzo, P.
Publication:		eprint arXiv:0809.2151
Publication Date:		09/2008
Origin:		ARXIV
Keywords:		Astrophysics
Comment:		paper to be published in COSPAR conference at Montreal
Bibliographic Code:		2008arXiv0809.2151C

Abstract

We illustrate some of the preliminary results obtained with a new sample of flares and a new analysis. In these proceedings we deal mainly with the analysis related to the flare energy and describe the work in progress to measure the average flare luminosity curve. We discuss in brief GRB050904 and GRB050724 for matters relevant to this work. In particular we measure the contribution given to the flares by GRB050904 and give a new interpretation for the decaying early XRT light curve of GRB050724. We briefly illustrate the first evidence that the early decay is given by the subsequent emission of events with Width/TPeak <> Bibtex entry for this abstract Preferred format for this abstract (see Preferences)

Malesani 2007 短暴GRB 050724的多波段余辉观测

主要内容:
宿主星系、光谱和多波段光变曲线

精彩摘抄:
position

light curves

文章信息:
arXiv:0706.1273 [ps, pdf, other] : Title: Multicolor observations of the afterglow of the short/hard GRB 050724
Authors: D. Malesani, S. Covino, P. D'Avanzo, V. D'Elia, D. Fugazza, S. Piranomonte, L. Ballo, S. Campana, L. Stella, G. Tagliaferri, L.A. Antonelli, G. Chincarini, M. Della Valle, P. Goldoni, C. Guidorzi, G.L. Israel, D. Lazzati, A. Melandri, P. Romano, G. Stratta, S.D. Vergani
Comments: 8 pages, 5 figures, 4 tables, submitted to A&A following referee comments

New information on short/hard gamma-ray bursts (GRBs) is being gathered thanks to the discovery of their optical and X-ray afterglows. However, some key aspects are still poorly understood, including the collimation level of the outflow, the duration of the central engine activity, and the properties of the progenitor systems. We want to constrain the physical properties of the short GRB 050724 and of its host galaxy, in turn drawing some inferences on the global short GRB population. We present optical observations of the afterglow of GRB 050724 and of its host galaxy, significantly expanding the existing dataset for this event. We compare our results with models, complementing them with available measurements in the literature. Including X-ray data, we study the afterglow light curve and spectrum. We also present observations of the host galaxy. The observed optical emission was likely related to the large flare observed in the X-ray light curve. The apparent steep decay was therefore not due to the jet effect. Available data are indeed consistent with low collimation, in turn implying a large energy release, comparable to that of long GRBs. The flare properties also constrain the internal shock mechanism, requiring a large Lorentz factor contrast between the colliding shells. This implies that the central engine was active at late times, rather than ejecting all shells simultaneously. The host galaxy has red colors and no ongoing star formation, consistent with previous findings on this GRB. However, it is not a pure elliptical, and has some faint spiral structure. GRB 050724 provides the most compelling case for association between a short burst and a galaxy with old stellar population. It thus plays a pivotal role in constraining progenitors models, which must allow long delays between birth and explosion.