A Correlation of Spectral Lag Evolution with Prompt Optical Emission in GRBs?
We report on observations of correlated behavior between the prompt γ-ray and optical emission from GRB080319B, which (i) strongly suggest that they occurred within the same astrophysical source region and (ii) indicate thattheir respective radiation mechanisms were most likely dynamically coupled. Our preliminary results, based upon a newcross-correlation function (CCF) methodology for determining the time-resolved spectral lag, are summarized as follows.First, the evolution in the arrival offset of prompt γ-ray photon counts between Swirl-BAT 15-25 keV and 50-100 keV energybands (intrinsic γ-ray spectral lag) appears to be anti-correlated with the arrival offset between prompt 15-350 keV γ-raysand the optical emission observed by TORTORA (extrinsic γ-ray/optical lag), thus effectively partitioning the burst into twomain episodes at∽T + 28±2 see. Second, prompt optical emission is nested within intervals of both (a) trivial intrinsic γ-rayspectral lag (∽T + 12 ±2 and∽T + 50 ±2 sec) with (b) discontinuities in the hard to soft evolution of the photon indexfor a power law fit to 15-150 keV Swift-BAT data (∽T + 8 ±2 and∽T + 48 ±1 sec), both of which coincide with the rise(∽T + 10 ±1 sec) and decline (∽T + 50±1 sec) of prompt optical emission. This potential discovery, robust across heuristicpermutations of BAT energy channels and varying temporal bin resolution, provides the first observational evidence for animplicit connection between spectral lag and the dynamics of shocks in the context of canonical fireball phenomenology.
gamma rays bursts,radiation mechanisms non-thermal,temporal aaalysis
Michael Stamatikos Tilan N.Ukwatta Taka Sakamoto Kalvir S.Dhuga
Astroparticle Physics Laboratory,Code 661,NASA/Goddard Space Flight Center Greenbelt,MD 20771 USA The George Washington University,Washington,DC 20052 USA CRESST,University of Maryland,Baltimore County,Baltimore,MD 21250 SA
国际会议
2008 NanJing Gamma-Ray Burst Conference(2008年伽马暴国际研讨会)
南京
英文
55-58
2008-06-23（万方平台首次上网日期，不代表论文的发表时间）