A comprehensive study of GRB 070125, a most energetic gamma-ray burst

Poonam Chandra, S. Bradley Cenko, Dale A. Frail, Roger A. Chevalier, Jean Pierre Macquart, Shri R. Kulkarni, Douglas C.J. Bock, Frank Bertoldi, Mansi Kasliwal, Derek B. Fox, Paul A. Price, Edo Berger, Alicia M. Soderberg, Fiona A. Harrison, Avishay Gal-Yam, Eran O. Ofek, Arne Rau, Brian P. Schmidt, P. Brian Cameron, Lennox L. CowieAntoinette Cowie, Katherine C. Roth, Michael Dopita, Bruce Peterson, Bryan E. Penprase

Research output: Contribution to journalArticlepeer-review

62 Scopus citations

Abstract

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 × 1017 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%).

Original languageEnglish (US)
Pages (from-to)924-942
Number of pages19
JournalAstrophysical Journal
Volume683
Issue number2
DOIs
StatePublished - Aug 20 2008

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

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