标题： 暗弱伽马射线暴在BATSE探测中的强度分布 显示英文标题

标题： The Intensity Distribution of Faint Gamma-ray Bursts Detected with BATSE

摘要： 我们最近完成了对6年档案BATSE数据的搜索，寻找那些太暗弱而无法激活航天器上实时爆发检测系统的伽马射线暴（GRBs）。 这些“未触发”的爆发可以与在航天器上检测到的“触发”爆发结合，产生一个伽马射线暴强度分布，其峰值通量比以前能研究的低两倍。 我们检测到的爆发在欧几里得空间中的V/Vmax统计值为0.177 +/- 0.006。 这个出人意料的低值是因为我们在4.096秒和8.192秒的时间尺度上检测到的爆发非常少（大多数爆发在此时间尺度上具有最高的信噪比），而这些爆发已经在1.024秒的时间尺度上被检测到了。 如果考虑到固有峰值光度的幂律分布，扩展的峰值通量分布与伽马射线暴率的红移分布大致追踪宇宙恒星形成历史的模型是一致的。 我们认为这类模型优于爆发率与红移无关的模型。 我们利用峰值通量分布得出一个限制，即在欧几里得空间中，空间均匀的爆发源子种群（如Ib/c型超新星）可能贡献的总爆发率的比例不超过10%（99%置信度）。 这些结果支持了之前研究的结论，即在BATSE onboard检测阈值以下将很少发现暗弱的“经典”GRBs。 显示英文摘要

摘要： We have recently completed a search of 6 years of archival BATSE data for gamma-ray bursts (GRBs) that were too faint to activate the real-time burst detection system running onboard the spacecraft. These "non-triggered" bursts can be combined with the "triggered" bursts detected onboard to produce a GRB intensity distribution that reaches peak fluxes a factor of 2 lower than could be studied previously. The value of the V/Vmax statistic (in Euclidean space) for the bursts we detect is 0.177 +/- 0.006. This surprisingly low value is obtained because we detected very few bursts on the 4.096 s and 8.192 s time scales (where most bursts have their highest signal-to-noise ratio) that were not already detected on the 1.024 s time scale. If allowance is made for a power-law distribution of intrinsic peak luminosities, the extended peak flux distribution is consistent with models in which the redshift distribution of the gamma-ray burst rate approximately traces the star formation history of the Universe. We argue that this class of models is preferred over those in which the burst rate is independent of redshift. We use the peak flux distribution to derive a limit of 10% (99% confidence) on the fraction of the total burst rate that could be contributed by a spatially homogeneous (in Euclidean space) subpopulation of burst sources, such as type Ib/c supernovae. These results lend support to the conclusions of previous studies predicting that relatively few faint "classical" GRBs will be found below the BATSE onboard detection threshold.