Nicuesa Guelbenzu 2001 短暴GRB 090426的喷流拐折

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时间是0.4天

精彩摘抄:

x射线和光学的光变，有拐折

红色的是短暴，灰色的是长暴

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Title:		GRB 090426: Discovery of a jet break in a short burst afterglow
Authors:		Nicuesa Guelbenzu, A.; Klose, S.; Rossi, A.; Kann, D. A.; Krühler, T.; Greiner, J.; Rau, A.;Olivares E., F.; Afonso, P. M. J.; Filgas, R.; Küpcü Yoldaş, A.; McBreen, S.; Nardini, M.; Schady, P.;Schmidl, S.; Updike, A. C.; Yoldaş, A.
Affiliation:		AA(Thüringer Landessternwarte Tautenburg, Sternwarte 5, 07778, Tautenburg, Germany ana@tls-tautenburg.de), AB()
Publication:		Astronomy & Astrophysics, Volume 531, id.L6 (A&A Homepage)
Publication Date:		07/2011
Origin:		EDP Sciences
Keywords:		gamma-ray burst: individual: GRB 090426
DOI:		10.1051/0004-6361/201116657
Bibliographic Code:		2011A&A...531L...6N

Abstract

Context. The link between the duration of GRBs and the nature of their progenitors remains disputed. Short bursts (with durations of less than ~2 s) are less frequently observed, technically more difficult to localize, and exhibit significantly fainter afterglows.
Aims: It is of critical importance to establish whether the burst duration can reliably distinguish the different GRB population models of collapsars and compact stellar mergers. The Swift GRB 090426 provides an unique opportunity to address this question. Its duration (T₉₀ = 1.28 s) places GRB 090426 firmly in the short burst population, while the high redshift (z = 2.609), host galaxy properties, and prompt emission spectral characteristics are more similar to those of long-duration GRBs.
Methods: On the basis of data obtained with the Tautenburg 2 m telescope (Germany) and the 7-channel imager GROND (La Silla, Chile), we compiled the most finely sampled light curve available for a short burst optical/NIR afterglow. The light curve was then analysed in a standard fashion. GROND and XRT data were used to determine the broad-band spectral energy distribution of the afterglow across more than three orders of magnitude.
Results: Our data show that a light curve break exists at 0.4 days, which is followed by a steep decay. This light curve decay is achromatic in the optical/NIR bands, and interpreted as a post-jet break phase. The X-ray data do not disagree with this interpretation.
Conclusions: The half-opening angle of the suspected jet as well as the luminosity of the optical afterglow provide additional evidence that GRB 090426 is probably linked to the death of a massive star rather than to the merger of two compact objects.Appendix A is available in electronic form at http://www.aanda.org

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