Observations of the Prompt Gamma-Ray Emission of GRB 070125

Abstract

The long, bright gamma-ray burst GRB 070125 was localized by the Interplanetary Network. We present light curves of the prompt gamma-ray emission as observed by Konus-WIND, RHESSI, Suzaku-WAM, and \textit{Swift}-BAT. We detail the results of joint spectral fits with Konus and RHESSI data. The burst shows moderate hard-to-soft evolution in its multi-peaked emission over a period of about one minute. The total burst fluence as observed by Konus is $1.79 \times 10^{-4}$ erg/cm$^2$ (20 keV--10 MeV). Using the spectroscopic redshift $z=1.548$, we find that the burst is consistent with the ``Amati'' $E_{peak,i}-E_{iso}$ correlation. Assuming a jet opening angle derived from broadband modeling of the burst afterglow, GRB 070125 is a significant outlier to the ``Ghirlanda'' $E_{peak,i}-E_\gamma$ correlation. Its collimation-corrected energy release $E_\gamma = 2.5 \times 10^{52}$ ergs is the largest yet observed.Comment: 25 pages, 6 figures; accepted for publication in ApJ. Improved spectral fits and energetics estimate