Jia 2008 BATSE hardness ratio with GRB light curves

主要内容:
According to the properties (the peak of HR curves and light curves didn't occur the same time mainly), they divided the burst into 4 classes.

精彩摘抄:

an example


文章信息:
On the trend of the hardness ratio evolutionary curve
of gamma-ray bursts
Lan-Wei Jia1,2

1National Astronomical Observatories/Yunnan Observatory, Chinese Academy of
Sciences, P. O. Box 110, Kunming 650011, China
2The Graduate School of the Chinese Academy of Sciences
Received month day; accepted month day
Abstract We analyzed a sample of 66 gamma-ray bursts (GRBs) and
statistically confirmed the prediction on the hardness ratio evolutionary
curve of GRBs made by Qin et al. (2006) based on the curvature effect. In
their analysis, GRB pulses are divided into three groups according to the
profile of their raw hardness ratio (RHR) curves. They defined RHR curve
by adding the background counts to the signal counts so that the hardness
ratio of counts within small time intervals can be evaluated. Among the
three types, very hard sources exhibit a perfect pulse-like profile (type 1),
hard bursts possess a pulse-like profile with a sinkage in its decaying phase
(type 2), and soft bursts show no pulse-like profile but have only a sinkage
profile (type 3). When analyzing type 3 sources in terms of the conventional
hardness ratio, they are indeed generally softer than those of type 1 and type
2, which is in agreement with the prediction. In addition, we found that the
minimum value of RHR is sensitive in distinguishing pulses of different
types. We propose that GRB pulses can be divided by the minimum value
of RHR and sources of different types might probably connect with different
strengthes of the shock or/and the magnetic field.

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