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arXiv · astro-ph/9612118

Evolution of the Low-Energy Photon Spectra in Gamma-Ray Bursts

A. Crider·E. P. Liang·I. A. Smith·R. D. Preece·M. S. Briggs·G. N. Pendleton·W. S. Paciesas·D. L. Band·J. L. Matteson
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Abstract

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 E_pk 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 E_pk 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 alpha_max equal to 1.6 +/- 0.3. These findings challenge GRB spectral models in which alpha must be negative of remain constant.

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A. Crider, E. P. Liang, I. A. Smith, R. D. Preece, M. S. Briggs, G. N. Pendleton, W. S. Paciesas, D. L. Band, J. L. Matteson. 1996-12-11. Evolution of the Low-Energy Photon Spectra in Gamma-Ray Bursts. https://doi.org/10.1086/310574

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