van der Horst, AJ;
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The rapidly flaring afterglow of the very bright and energetic GRB 070125.
361 - 375.
We report on multiwavelength observations, ranging from X-ray to radio wave bands, of the IPN-localized gamma-ray burst GRB 070125. Spectroscopic observations reveal the presence of absorption lines due to O I, Si II, and C IV, implying a likely redshift of z = 1.547. The well-sampled light curves, in particular from 0.5 to 4 days after the burst, suggest a jet break at 3.7 days, corresponding to a jet opening angle of similar to 7.0 degrees, and implying an intrinsic GRB energy in the 1-10,000 keV band of around E-gamma = (6.3-6.9) x 10(51) ergs (based on the fluences measured by the gamma-ray detectors of the IPN). GRB 070125 is among the brightest afterglows observed to date. The SED implies a host extinction of A(V) < 0. 9 mag. Two rebrightening episodes are observed, one with excellent time coverage, showing an increase in flux of 56% in similar to 8000s. The evolution of the afterglow light curve is achromatic at all times. Late-time observations of the afterglow do not show evidence for emission from an underlying host galaxy or supernova. Any host galaxy would be subluminous, consistent with current GRB host galaxy samples. Evidence for strong Mg II absorption features is not found, which is perhaps surprising in view of the relatively high redshift of this burst and the high likelihood for such features along GRB-selected lines of sight.
|Title:||The rapidly flaring afterglow of the very bright and energetic GRB 070125|
|Keywords:||gamma rays : bursts, GAMMA-RAY-BURST, 29 MARCH 2003, AUTOMATIC IMAGING TELESCOPE, BLAST WAVE PHYSICS, 28 FEBRUARY 1997, OPTICAL AFTERGLOW, HOST-GALAXY, LIGHT-CURVE, COSMIC REIONIZATION, SUPERNOVA LIGHT|
|UCL classification:||UCL > School of BEAMS > Faculty of Maths and Physical Sciences > Space and Climate Physics|
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