The Broken Light Curves of Gamma-Ray Bursts GRB 990123 and GRB 990510

Details The Broken Light Curves of Gamma-Ray Bursts GRB 990123 and GRB 990510 The Broken Light Curves of Gamma-Ray Bursts GRB 990123 and GRB 990510

2000-10-10

arxiv.org/abs/astro-ph/0010196v2

Astron.Astrophys.364:467-478,2000

Astronomy and Astrophysics

Astrophysics

13 pages, 10 encapsulated postscript figures, uses aa.cls (v4.05) Published in Astronomy & Astrophysics Replacement, minor typ

Scientific paper

We have collected all of the published photometry for GRB 990123 and GRB 990510, the first two gamma-ray bursts where breaks were seen in the light curves of their optical afterglows, and determined the shapes of their light curves and the break times. These parameters were used to investigate the physical mechanisms responsible for the breaks and the nature of the ambient medium that the bursts occurred in. The light curve for GRB 990123 is best fit by a broken power law with a break 1.68 +/- 0.19 days after the burst, a slope of alpha1 = -1.12 +/- 0.08 before the break, and a slope of alpha2 = -1.69 +/- 0.06 after the break. This is consistent with a collimated outflow with a fixed opening angle (theta0) of approximately five degrees. In this case the break in the light curve is due to the relativistic fireball slowing to a gamma factor of approximately 1 / theta0. The light curve for GRB 990510 is best fit by a continuous function with an early-time slope of alpha1 = -0.54 +/- 0.14, a late-time slope of alpha2 = -1.98 +/- 0.19, and a slow transition between the two regimes approximately one day after the burst. This is consistent with a collimated outflow with an opening angle of approximately five degrees that is initially radiative, but undergoes a sideways expansion that begins approximately one day after the burst. This sideways expansion is responsible for the slow break in the light curve.

Affiliated with

Also associated with

No associations

Rating

The Broken Light Curves of Gamma-Ray Bursts GRB 990123 and GRB 990510 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 The Broken Light Curves of Gamma-Ray Bursts GRB 990123 and GRB 990510, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and The Broken Light Curves of Gamma-Ray Bursts GRB 990123 and GRB 990510 will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-722588