2007A&A...469L..13M

Query : 2007A&A...469L..13M

2007A&A...469L..13M - Astronomy and Astrophysics, volume 469, L13-16 (2007/7-1)

REM observations of GRB 060418 and GRB 060607A: the onset of the afterglow and the initial fireball. Lorentz factor determination.

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. and VALENZUELA J.

Abstract (from CDS):

Gamma-ray burst (GRB) emission is believed to originate in highly relativistic fireballs. Currently, only lower limits were securely set to the initial fireball Lorentz factor Γ₀. We aim to provide a direct measure of Γ₀. The early-time afterglow light curve carries information about Γ₀, 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. For both events, the afterglow peak could be clearly singled out, allowing a firm determination of the fireball Lorentz of Γ₀∼400, fully confirming the highly relativistic nature of GRB fireballs. The deceleration radius was inferred to be R_dec≃10¹⁷cm. 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.

Abstract Copyright: ∼

Journal keyword(s): gamma rays: bursts - relativity

Simbad objects: 14

Full paper

View the references in ADS

Number of rows : 14

N	Identifier	Otype	ICRS (J2000) RA	ICRS (J2000) DEC	Mag U	Mag B	Mag V	Sp type	#ref 1850 - 2023	#notes
1	GRB 041219	gB	00 24 27.7	+62 50 34				~	223	1
2	GRB 021004	gB	00 26 54.68	+18 55 41.6				~	539	0
3	GRB 050904	gB	00 54 50.794	+14 05 09.42				~	460	0
4	GRB 060210	gB	03 50 57.370	+27 01 34.40		20.27		~	249	0
5	GRB 060124	gB	05 08 25.900	+69 44 26.98		18.91	17.35	~	258	0
6	SN 2002lt	SN*	08 08 59.858	+06 43 37.52				SNIc:	348	1
7	GRB 030418	gB	10 54 33.69	-07 01 40.8				~	68	0
8	GRB 060206	gB	13 31 43.420	+35 03 03.60		19.99	17.09	~	308	0
9	GRB 050801	gB	13 36 35.000	-21 55 41.00	15.03	15.82	15.46	~	155	0
10	GRB 050730	gB	14 08 17.090	-03 46 18.90		20.32	17.68	~	306	0
11	GRB 990123	gB	15 25 29	+44 45.0			8.95	~	984	1
12	GRB 060418	gB	15 45 42.600	-03 38 20.00	15.73	16.19	14.98	~	354	0
13	GRB 060607	gB	21 58 50.400	-22 29 46.70	18.49	16.67	15.09	~	291	0
14	GRB 050820A	gB	22 29 38.110	+19 33 37.10	18.33	19.00	18.47	~	379	0

To bookmark this query, right click on this link: simbad:objects in 2007A&A...469L..13M and select 'bookmark this link' or equivalent in the popup menu