Evolution of the low-energy photon spectra in gamma-ray bursts

被引:205
作者
Crider, A
Liang, EP
Smith, IA
Preece, RD
Briggs, MS
Pendleton, GN
Paciesas, WS
Band, DL
Matteson, JL
机构
[1] UNIV ALABAMA,DEPT PHYS,HUNTSVILLE,AL 35899
[2] UNIV CALIF SAN DIEGO,CTR ASTROPHYS & SPACE SCI 0111,LA JOLLA,CA 92093
基金
美国国家航空航天局;
关键词
gamma rays; bursts; observations; methods; statistical; BATSE OBSERVATIONS;
D O I
10.1086/310574
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
We report evidence that the asymptotic low-energy power-law slope ct (below the spectral break) of BATSE gamma-ray burst (GRB) photon spectra evolves with time rather than remaining constant. We find that 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 an alpha(max) equal to 1.6 +/- 0.3. These findings challenge GRB spectral models in which alpha must be negative or remain constant.
引用
收藏
页码:L39 / L42
页数:4
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