1996/12/11 by A. Crider, Edison Liang, E. P. Liang +8 · 4 citations
Physics and Astronomy · #Gamma-ray bursts and supernovae #Pulsars and Gravitational Waves Research #astro-ph
paper · pdf · doi:10.1086/310574
published as Astrophys.J. 479 (1997) 39 · 12 pages (including 6 figures), accepted to ApJ
arxiv created 1996/12/11 · openalex publication_date 1997/04/10 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
We report evidence that the asymptotic low-energy power law slope alpha (below the spectral break) of BATSE gamma-ray burst photon spectra evolves with time rather than remaining constant. We find a high degree of positive correlation exists between the time-resolved spectral break energy Epk and alpha. In samples of 18 "hard-to-soft" and 12 "tracking" pulses, evolution of alpha was found to correlate with that of the spectral break energy Epk at the 99.7% and 98% confidence levels respectively. We also find that in the flux rise phase of "hard-to-soft" pulses, the mean value of alpha is often positive and in some bursts the maximum value of alpha is consistent with a value > +1. BATSE burst 3B 910927, for example, has a alphamax equal to 1.6 +/- 0.3. These findings challenge GRB spectral models in which alpha must be negative of remain constant.