A Comparison of the Afterglows of Short- and Long-Duration Gamma-Ray Bursts

Understand

We present a comparative study of the observed properties of the optical and X-ray afterglows of short- and long-duration gamma-ray bursts (GRBs).

• Using a large sample of 37 short and 421 long GRBs, we find a strong correlation between the afterglow brightness measured after 11 hours and the observed fluence of the prompt emission.
• Both the optical (R band) and X-ray flux densities (F_R and F_X) scale with the gamma-ray fluence, F_gamma.
• For bursts with a known redshift, a tight correlation exists between the afterglow flux densities at 11 hours (rest-frame) and the total isotropic gamma-ray energy, Egi: F_{R,X} ~ Egi^{alpha}, with alpha ~ 1.