2011A&A...526A.154A


C.D.S. - SIMBAD4 rel 1.7 - 2020.08.07CEST11:41:36

2011A&A...526A.154A - Astronomy and Astrophysics, volume 526A, 154-154 (2011/2-1)

GRB 050502B optical afterglow: a jet-break at high redshift.

AFONSO P., GREINER J., PIAN E., COVINO S., MALESANI D., KUEPCUE YOLDAS A., KRUEHLER T., CLEMENS C., McBREEN S., RAU A., GIANNIOS D. and HJORTH J.

Abstract (from CDS):

Swift GRB050502B is well known for the very bright flare displayed in its X-ray light curve. Despite extensive studies, however, the optical light curve has never been discussed and its redshift is unconstrained. Possible correlations between optical and X-ray data are analysed. Photometric data from TNG in the R and I bands were used to compare the optical afterglow with the X-ray light curve. The HyperZ package and a late-time VLT host observation were used to derive redshift estimates. The I-band afterglow decay followed a power law of index α=2.1±0.6, after a late break at ∼1.3x105s. The R-I colour is remarkably red and the broadband spectral index βOX=0.9±0.1 is consistent with the X-ray spectral slope βX. Although a photometric redshift of z>4 is the most conservative result to consider, a photometric redshift of z=5.2±0.3 is suggested with no extinction in the host, based on which an isotropic energy Eγ,iso=(3.8±0.7)x1052erg and a jet opening angle θ∼3.7° are subsequently derived. The combined X-ray and optical data suggest an achromatic break, which we interpret as a jet-break. The post jet-break slope roughly obeys the closure relation for the jet's slow cooling model. Because of the afterglow's very red colour, in order for the redshift to be low (z<1), extinction must be significantly high if present in the host. Since the optical-to-X-ray index is consistent with the X-ray spectrum, and there is no XRT evidence for excess NH, GRB 050502B was likely at high redshift.

Abstract Copyright:

Journal keyword(s): gamma-ray burst: general - gamma-ray burst: individual: GRB 050502B

Simbad objects: 6

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Number of rows : 6

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2020
#notes
1 NAME SMC G 00 52 38.0 -72 48 01   2.79 2.2     ~ 9476 1
2 GRB 080916C gB 07 59 23.24 -56 38 16.8           ~ 317 0
3 GRB 050502B gB 09 30 10.024 +16 59 48.07           ~ 150 0
4 GRB 070306 gB 09 52 23.220 +10 28 55.20           ~ 178 1
5 GRB 060923A gB 16 58 28.150 +12 21 38.90           ~ 58 0
6 GRB 071010A gB 19 12 14.42 -32 24 06.2           ~ 106 0

    Equat.    Gal    SGal    Ecl

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2020.08.07-11:41:36

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