Cenko, S. B. and Kasliwal, M. and Harrison, F. A. and Pal'shin, V. and Frail, D. A. and Cameron, P. B. and Berger, E. and Fox, D. B. and Gal-Yam, A. and Kulkarni, S. R. and Moon, D.-S. and Nakar, E. and Ofek, E. O. and Penprase, B. E. and Price, P. A. and Sari, R. and Schmidt, B. P. and Soderberg, A. M. and Aptekar, R. and Frederiks, D. and Golenetskii, S. and Burrows, D. N. and Chevalier, R. A. and Gehrels, N. and McCarthy, P. J. and Nousek, J. A. and Piran, T. (2006) Multiwavelength observations of GRB 050820A : an exceptionally energetic event followed from start to finish. Astrophysical Journal, 652 (1). pp. 490-506. ISSN 0004-637X http://resolver.caltech.edu/CaltechAUTHORS:CENapj06
- Published Version
Restricted to Repository administrators only
See Usage Policy.
Use this Persistent URL to link to this item: http://resolver.caltech.edu/CaltechAUTHORS:CENapj06
We present observations of the unusually bright and long γ-ray burst GRB 050820A, one of the best sampled broadband data sets in the Swift era. The γ-ray light curve is marked by a soft precursor pulse some 200 s before the main event; the lack of any intervening emission suggests that it is due to a physical mechanism distinct from the GRB itself. The large time lag between the precursor and the main emission enabled simultaneous observations in the γ-ray, X-ray, and optical bandpasses, something only achieved for a handful of events to date. While the contemporaneous X-rays are the low-energy tail of the prompt emission, the optical does not directly track the γ-ray flux. Instead, the early-time optical data appear consistent with the forward shock synchrotron peak passing through the optical and are therefore likely the beginning of the afterglow. On hour timescales after the burst, the X-ray and optical light curves are inconsistent with an adiabatic expansion of the shock into the surrounding region, but rather indicate that there is a period of energy injection. Observations at late times allow us to constrain the collimation angle of the relativistic outflow to 6°.8 ≾ θ ≾ 9°.3. Our estimates of both the kinetic energy of the afterglow (EKE = 5.2^(+7.9)_(4.1) × 10^(51) ergs) and the prompt γ-ray energy release (Eγ = 7.5^(+6.7)-(2.4) × 10^(51) ergs) make GRB 050820A one of the most energetic events for which such values could be determined.
|Additional Information:||© 2006 The American Astronomical Society. Received 2006 May 18; accepted 2006 August 2. We would like to thank the anonymous referee for helpful comments on this manuscript. S. B. C. and A. M. S. are supported by the NASA Graduate Student Research Program. E. B. is supported by NASA through Hubble Fellowship grant HSTHF- 01171.01 awarded by STScI, which is operated by the Association of Universities for Research in Astronomy, Inc., for NASA, under contract NAS5-26555. A. G. acknowledges support by NASA through Hubble Fellowship grant HST-HF-01158.01 awarded by STScI. The Konus-Wind experiment is supported by Russian Space Agency contract and RFBR grant 06-02-16070. GRB research at Caltech is supported through NASA. This publication has made use of data obtained from the Swift interface of the High-Energy Astrophysics Archive (HEASARC), provided by NASA’s Goddard Space Flight Center. This publication makes use of data products from the Two Micron All Sky Survey, which is a joint project of the University of Massachusetts and the Infrared Processing and Analysis Center/California Institute of Technology, funded by the National Aeronautics and Space Administration and the National Science Foundation. The Digitized Sky Survey was produced at the Space Telescope Science Institute under US Government grant NAG W-2166. The images of these surveys are based on photographic data obtained using the Oschin Schmidt Telescope on Palomar Mountain and the UK Schmidt Telescope. The plates were processed into the present compressed digital form with the permission of these institutions.|
|Group:||Space Radiation Laboratory|
|Subject Keywords:||gamma rays: bursts; X-rays: individual (GRB 050820A)|
|Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||Tony Diaz|
|Deposited On:||09 Jul 2009 18:11|
|Last Modified:||04 Mar 2013 18:53|
Repository Staff Only: item control page