GRB990123: Evidence that the Gamma Rays Come from a Central Engine

Details GRB990123: Evidence that the Gamma Rays Come from a Central Engine GRB990123: Evidence that the Gamma Rays Come from a Central Engine

1999-02-02

arxiv.org/abs/astro-ph/9902007v1

Astronomy and Astrophysics

Astrophysics

14 pages, 3 embedded figues, Latex, Submitted to ApJL

Scientific paper

10.1086/312075

GRB990123 was a long complex gamma-ray burst with an optical transient that started early within the gamma-ray phase. The peak and power law decay of the early optical emission strongly indicates the presence of a decelerating relativistic shell during that phase. Prior to this burst, it was not known if the shell decelerated during the burst, so an external shock origin for the gamma rays was still possible. If the gamma-rays are produced in the external shock, then the pulse widths should reflect the observed deceleration of the shell and increase by about 2.3. We analyze the fine time structure observed in the gamma-ray data from BATSE and determine that the width of the peaks do not increase as expected for a decelerating shell; the later pulses are, at most, a factor of 1.15 longer than the earlier pulses. We also analyze the variability to determine what fraction of the shell's surface could be involved in the production of the gamma rays, the so-called surface filling factor. For GRB990123 we find a filling factor of 0.008. The lack of pulse width evolution eliminates the only remaining kinematically acceptable external shock explanation for the gamma-ray phase and, thus, the gamma rays must originate at a central engine.

Affiliated with

Also associated with

No associations

Rating

GRB990123: Evidence that the Gamma Rays Come from a Central Engine does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with GRB990123: Evidence that the Gamma Rays Come from a Central Engine, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and GRB990123: Evidence that the Gamma Rays Come from a Central Engine will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-457785