REM observations of GRB060418 and GRB060607A: the onset of the afterglow and the initial fireball Lorentz factor determination

被引：241

作者：

Molinari, E.

Vergani, S. D.

Malesani, D.

Covino, S.

D'Avanzo, P.

Chincarini, G.

Zerbi, F. M.

Antonelli, L. A.

Conconi, P.

Testa, V.

Tosti, G.

Vitali, F.

D'Alessio, F.

Malaspina, G.

Nicastro, L.

Palazzi, E.

Guetta, D.

Campana, S.

Goldoni, P.

Masetti, N.

Meurs, E. J. A.

Monfardini, A.

Norci, L.

Pian, E.

Piranomonte, S.

Rizzuto, D.

Stefanon, M.

Stella, L.

Tagliaferri, G.

Ward, P. A.

Ihle, G.

Gonzalez, L.

Pizarro, A.

Sinclaire, P.

Valenzuela, J.

机构：

[1] Osserv Astron Brera, INAF, I-23807 Merate, LC, Italy

[2] DIAS, Dunsink Observ, Dublin 15, Ireland

[3] Dublin City Univ, Sch Phys Sci, Dublin 9, Ireland

[4] Dublin City Univ, NCPST, Dublin 9, Ireland

[5] SISSA, ISAS, I-34014 Trieste, Italy

[6] Univ Copenhagen, Niels Bohr Inst, Dark Cosmol Ctr, DK-2100 Copenhagen, Denmark

[7] Univ Insubria, Dipartimento Matemat & Fis, I-22100 Como, Italy

[8] Univ Milan, I-20126 Milan, Italy

[9] Osserv Astron Roma, INAF, I-00040 Monte Porzio Catone, Italy

[10] Univ Perugia, Dipartimento Fis, I-06123 Perugia, Italy

[11] Univ Perugia, Osservatorio Astron, I-06123 Perugia, Italy

[12] IASF Bologna, INAF, I-40129 Bologna, Italy

[13] APC, Lab Astroparticule & Cosmol, UMR 7164, F-75231 Paris 05, France

[14] CEA Saclay, DSM, DAPNIA, Serv Astrophys, F-91191 Gif Sur Yvette, France

[15] CNRS, Inst Nel, F-38042 Grenoble, France

[16] Osserv Astron Trieste, INAF, I-34143 Trieste, Italy

[17] European So Observ, Santiago 19, Chile

来源：

ASTRONOMY & ASTROPHYSICS | 2007年 / 469卷 / 01期

关键词：

gamma rays : bursts; relativity;

D O I：

10.1051/0004-6361:20077388

中图分类号：

P1 [天文学];

学科分类号：

0704 ;

摘要：

Context. Gamma-ray burst (GRB) emission is believed to originate in highly relativistic fireballs. Aims. Currently, only lower limits were securely set to the initial fireball Lorentz factor Gamma(0). We aim to provide a direct measure of Gamma(0). Methods. The early-time afterglow light curve carries information about Gamma(0), which determines the time of the afterglow peak. We have obtained early observations of the near-infrared afterglows of GRB060418 and GRB060607A with the REM robotic telescope. Results. For both events, the afterglow peak could be clearly singled out, allowing a firm determination of the fireball Lorentz of Gamma(0) similar to 400, fully confirming the highly relativistic nature of GRB fireballs. The deceleration radius was inferred to be R-dec approximate to 10(17) cm. This is much larger than the internal shocks radius (believed to power the prompt emission), thus providing further evidence for a different origin of the prompt and afterglow stages of the GRB.

引用

页码：L13 / U16

页数：6

共 61 条

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