2011A&A...535A..57F


C.D.S. - SIMBAD4 rel 1.7 - 2019.07.18CEST22:25:59

2011A&A...535A..57F - Astronomy and Astrophysics, volume 535A, 57-57 (2011/11-1)

GRB 091127: the cooling break race on magnetic fuel.

FILGAS R., GREINER J., SCHADY P., KRUEHLER T., UPDIKE A.C., KLOSE S., NARDINI M., KANN D.A., ROSSI A., SUDILOVSKY V., AFONSO P.M.J., CLEMENS C., ELLIOTT J., NICUESA GUELBENZU A., OLIVARES E.F. and RAU A.

Abstract (from CDS):

Using high-quality, broad-band afterglow data for GRB 091127, we investigate the validity of the synchrotron fireball model for gamma-ray bursts (GRBs), and infer physical parameters of the ultra-relativistic outflow. We used multi-wavelength (NIR to X-ray) follow-up observations obtained with GROND simultaneously in the g'r'i'z'JH filters and the XRT onboard the Swift satellite in the 0.3 to 10 keV energy range. The resulting afterglow light curve is of excellent accuracy with relative photometric errors as low as 1%, and the spectral energy distribution (SED) is well-sampled over 5 decades in energy. These data present one of the most comprehensive observing campaigns for a single GRB afterglow and allow us to test several proposed emission models and outflow characteristics in unprecedented detail. Both the multi-color light curve and the broad-band SED of the afterglow of GRB 091127 show evidence of a cooling break moving from high to lower energies. The early light curve is well described by a broken power-law, where the initial decay in the optical/NIR wavelength range is considerably flatter than at X-rays. Detailed fitting of the time-resolved SED shows that the break is very smooth with a sharpness index of 2.2±0.2, and evolves towards lower frequencies as a power-law with index -1.23±0.06. These are the first accurate and contemporaneous measurements of both the sharpness of the spectral break and its time evolution. The measured evolution of the cooling break (νc∝t~–1.2) is not consistent with the predictions of the standard model, wherein νc∝t~–0.5 is expected. A possible explanation for the observed behavior is a time dependence of the microphysical parameters, in particular the fraction of the total energy in the magnetic field εB. This conclusion provides further evidence that the standard fireball model is too simplistic, and time-dependent micro-physical parameters may be required to model the growing number of well-sampled afterglow light curves.

Abstract Copyright:

Journal keyword(s): ISM: jets and outflows - X-rays: bursts - X-rays: individual: GRB 091127

VizieR on-line data: <Available at CDS (J/A+A/535/A57): phot.dat table5.dat>

Simbad objects: 15

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Number of rows : 15

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2019
#notes
1 GRB 021004 gB 00 26 54.68 +18 55 41.6           ~ 507 1
2 NAME SMC G 00 52 38.0 -72 48 01   2.79 2.2     ~ 8998 1
3 GRB 041218 gB 01 39 07.6 +71 20 30           ~ 32 0
4 GRB 040924 gB 02 06 22.52 +16 08 48.8           ~ 145 1
5 SN 2009nz SN* 02 26 19.87 -18 57 08.6           SN.? 217 1
6 GSC 00048-01015 * 02 57 21.2100302481 +00 18 38.643655747 12.136 12.028 11.725 11.549 11.363 A2 31 0
7 NAME Magellanic Clouds GrG 03 00 -71.0           ~ 5298 1
8 NAME LMC G 05 23 34.6 -69 45 22     0.4     ~ 14182 1
9 GRB 060729 gB 06 21 31.850 -62 22 12.69           ~ 238 0
10 SN 2003dh SN* 10 44 50.030 +21 31 18.15     16.2     SN.IcPec 1097 2
11 GRB 050408 gB 12 02 17.320 +10 51 10.00           ~ 140 0
12 GRB 050502A gB 13 29 46.250 +42 40 27.50           ~ 55 0
13 GRB 990510 gB 13 38 07.64 -80 29 48.8           ~ 461 1
14 GRB 080319B gB 14 31 41.04 +36 18 09.2           ~ 414 0
15 GRB 050525A gB 18 32 32.560 +26 20 22.34 14.19 15.17 13.91     SN.Ic: 340 1

    Equat.    Gal    SGal    Ecl

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2019.07.18-22:25:59

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