Chandra, Poonam and Cenko, S. Bradley and Frail, Dale A. and Chevalier, Roger A. and Macquart, Jean-Pierre and Kulkarni, Shri R. and Bock, Douglas C.-J. and Bertoldi, Frank and Kasliwal, Mansi and Fox, Derek B. and Price, Paul A. and Berger, Edo and Soderberg, Alicia M. and Harrison, Fiona A. and Gal-Yam, Avishay and Ofek, Eran O. and Rau, Arne and Schmidt, Brian P. and Cameron, P. Brian and Cowie, Lennox L. and Cowie, Antionette and Roth, Katherine C. and Dopita, Michael and Peterson, Bruce and Penprase, Bryan E. (2008) A comprehensive study of GRB 070125, a most energetic gamma-ray burst. Astrophysical Journal, 689 (2). pp. 924-942. ISSN 0004-637X http://resolver.caltech.edu/CaltechAUTHORS:20090618-204832185
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We present a comprehensive multiwavelength analysis of the bright, long-duration gamma-ray burst GRB 070125, comprised of observations in gamma-ray, X-ray, optical, millimeter, and centimeter wave bands. Simultaneous fits to the optical and X-ray light curves favor a break on day 3.78, which we interpret as the jet break from a collimated outflow. Independent fits to optical and X-ray bands give similar results in the optical bands but shift the jet break to around day 10 in the X-ray light curve. We show that for the physical parameters derived for GRB 070125, inverse Compton scattering effects are important throughout the afterglow evolution. While inverse Compton scattering does not affect radio and optical bands, it may be a promising candidate to delay the jet break in the X-ray band. Radio light curves show rapid flux variations, which are interpreted as due to interstellar scintillation and used to derive an upper limit of 2.4 × 10^(17) cm on the radius of the fireball in the lateral expansion phase of the jet. Radio light curves and spectra suggest a high synchrotron self-absorption frequency indicative of the afterglow shock wave moving in a dense medium. Our broadband modeling favors a constant density profile for the circumburst medium over a windlike profile (R^(−2)). However, keeping in mind the uncertainty of the parameters, it is difficult to unambiguously distinguish between the two density profiles. Our broadband fits suggest that GRB 070125 is a burst with high radiative efficiency (>60%).
|Additional Information:||© 2008 American Astronomical Society. Received 2008 January 18, accepted for publication 2008 April 30. Print publication: Issue 2 (2008 August 20). P. C. thanks the VLA staff for making radio observations, without which this work was not possible. P. C. is a Jansky Fellow at the National Radio Astronomy Observatory. The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc. We thank Sarah Yost for providing us with the GRB broadband modeling code and helping out in running the code. P. C. used the fussy calculator (http://fussy.googlecode.com) for error propagation calculations and wishes to thank its author, Sanjay Bhantagar. R. A. C. was supported in part by NASA grant NNG06GJ33G.|
|Group:||Space Radiation Laboratory|
|Subject Keywords:||gamma rays: bursts; gamma rays: observations; radiation mechanisms: general; techniques: radar astronomy; X-rays: bursts|
|Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||Joy Painter|
|Deposited On:||12 Aug 2009 22:04|
|Last Modified:||04 Mar 2013 18:55|
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