[vsnet-grb-info 12258] GRB 120804A: Possible temporal break in the X-ray light-curve

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  13643
SUBJECT: GRB 120804A: Possible temporal break in the X-ray light-curve
DATE:    12/08/14 20:56:06 GMT
FROM:    Wen-fai Fong at CFA  <wfong at cfa.harvard.edu>

R. Margutti, W. Fong, and E. Berger (Harvard) report:

"We analyzed the Swift-XRT and Chandra observations of the short GRB
120804A (Lien et al. GCN 13573; Troja et al., GCN 13640). Using the data at
t>10^4 sec, when the light curve appears less susceptible to variability,
we find moderate evidence for a temporal break with a pre-break index of
alpha1= 0.7 +\- 0.1, a post-break index of alpha2= 1.9 +\- 0.5, and a break
time of about 2x10^5 sec. The F-test indicates 5% probability of chance
improvement with respect to a single power-law fit.  Plots are available
from:

https://www.cfa.harvard.edu/~rmargutt/flux_lightcurvefitBPL.pdf
https://www.cfa.harvard.edu/~rmargutt/flux_lightcurvefitSPL.pdf

Further X-ray observations are required to clarify the nature/presence of
the temporal break."