Combining results from Schmidt for the local cosmic rate and mean peak luminosity of γ-ray bursts (GRBs) with results on the history of the cosmic star formation rate (SFR), we provide estimates for the local GRB rate per unit blue luminosity in galaxies. For a moderate increase in SFR with redshift, we find a GRB rate per unit B luminosity of 2.4 x 10~(-17) h_(70)~2 solr luminosity~(-1) yr~(-1). The corresponding mean γ-ray lumi-nosity density in the Milky Way is 1.6 x 10~(29) ergs s~(-1) pc~(-2), and the total rate is 5.5 x 10~7 h_(70)~2 yr~(-1). These values are used to examine a number of phenomena with the following conclusions: (1) The ratio of supernova rate to isotropic equivalent GRB rate is large: approx>6000 SNe Ibc per GRB, approx> 30,000 SNe Ⅱ per GRB. With no correction for collimation, it is difficult to maintain that more than a small fraction of neutron star- or black hole-forming events produce GRBs. GRBs could arise in a large fraction of black hole- or magnetar-forming events only with collimation in the range ΔΩ/4π ～ 0.01-0.001 and a steep enough slope of the initial mass function. (2) Without substantial collimation, the GRB rate is small; with collimation, the energy input is small. The net effect is that it is impossible to use these events to account for the majority of large H Ⅰ holes observed in our own and other galaxies. (3) Modeling the GRB events in the Milky Way as a spatial Poisson process and allowing for modest enhancement in the star formation rate due to birth in a spiral arm, we find that the probability that the solar system was exposed to a fluence large enough to melt the chondrules during the first 10~7 yr of solar system history is negligibly small, independent of collimation effects. This is especially true considering that there is strong evidence that the chondrules were melted more than once. (4) We calculate the probability that surfaces of planets and satellites have been subjected to irradiation from GRBs at fluence levels exceeding those required for DNA alterations during a given period of time. Downscattering to energies at which photoelectric absorption occurs results in a transmission factor for ionizing radiation that is an exponential function of the atmospheric column density. Even for very opaque atmospheres, a significant fraction of the GRB energy is transmitted as UV lines because of excitation by secondary electrons. For eukaryotic-like organisms in thin atmospheres (e.g., contemporary Mars) or for UV line exposure in thick atmospheres (e.g., Earth), biologically significant events occur at a rate of ～ 100-500 Gyr~(-1). The direct contribution of these "jolts" to mutational evolution may, however, be negligible because of the short duration of the GRBs. Evolutionary effects due to partial sterilizations and to longer lived disruptions of atmospheric chemistry should be more important.
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机译：将施密特（Schmidt）的局部宇宙率和γ射线爆发（GRBs）的平均峰值发光度与宇宙恒星形成率（SFR）的历史结果相结合，我们提供了星系中每单位蓝色发光度的局部GRB率估计值。对于伴随红移的SFR的适度增加，我们发现每单位B发光度的GRB率为2.4 x 10〜（-17）h_（70）〜2 solr发光度〜（-1）yr〜（-1）。银河系中相应的平均γ射线发光密度为1.6 x 10〜（29）ers s〜（-1）pc〜（-2），总速率为5.5 x 10〜7 h_（70） 〜2年〜（-1）。这些值用于检验许多现象，并得出以下结论：（1）超新星速率与各向同性等效GRB速率之比很大：每个GRB大约> 6000 SNe Ibc，每个GRB大约> 30,000 SNeⅡ。如果不进行准直校正，则很难维持产生一小部分中子星或黑洞形成事件产生GRB。仅在ΔΩ/4π〜0.01-0.001范围内的准直度和初始质量函数的足够陡峭的斜率下，GRB才可能出现在很大一部分的黑洞或磁场形成事件中。 （2）没有大量准直，GRB率很小;准直时，能量输入很小。最终结果是，不可能使用这些事件来解释在我们自己的星系和其他星系中观察到的大多数HⅠ大孔。 （3）将银河系中的GRB事件建模为空间泊松过程，并考虑到由于旋臂中的诞生而使恒星形成率适度提高，我们发现太阳系受到足够大的通量的概率在太阳系历史的前10到7年中，融化软骨是很小的，与准直效应无关。考虑到有充分的证据表明软骨的融化不止一次，这一点尤其正确。 （4）我们计算出在给定的时间内，行星和卫星表面受到能量密度超过DNA改变所需能量密度的GRB辐射的概率。向下散射到发生光电吸收的能量会导致电离辐射的透射率，这是大气柱密度的指数函数。即使对于非常不透明的大气，由于二次电子的激发，GRB能量的很大一部分仍会作为UV线传输。对于在稀薄大气中（如当代火星）的真核生物，或在厚大气层（如地球）中的紫外线辐射，生物学上重要的事件发生的速率约为100-500 Gyr〜（-1）。但是，由于GRB持续时间短，这些“颠簸”对突变进化的直接贡献可以忽略不计。由于部分灭菌和大气化学作用的长期破坏而产生的进化效应应该更为重要。
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