伽马射线暴对地球生命的威胁
Gamma-Ray Bursts as a Threat to Life on Earth
摘要：
伽马射线暴（GRB）在过去的10亿年中可能对地球产生了许多重大影响。在几千秒差距内爆发的伽马辐射将迅速耗尽地球的大部分保护臭氧层，使到达地表的太阳紫外线辐射增加。这种辐射对生命有害，破坏DNA并导致晒伤。此外，大气中产生的NO2会导致到达地表的可见阳光减少，并可能导致全球变冷。硝酸雨可能会对生物圈的某些部分造成压力，但硝酸盐沉积的增加可能有助于陆地植物。我们已经使用了一个二维的大气模型，以研究在地球大气中的伽玛射线暴提供一系列的注量，在不同的纬度，在分点和至点，并在不同的时间一天的影响。我们已经估计了DNA损伤水平所造成的增加太阳UVB辐射，减少太阳可见光，由于NO2不透明，和硝酸盐的沉积通过雨出HNO3。在本文中，我简要回顾了这项工作，并讨论了目前和未来的工作，扩大和改善我们的估计地面的伽玛射线暴的影响。
英文摘要：
Gamma-ray bursts (GRBs) are likely to have made a number of significant impacts on the Earth during the last billion years. The gamma radiation from a burst within a few kiloparsecs would quickly deplete much of the Earth's protective ozone layer, allowing an increase in solar ultraviolet radiation reaching the surface. This radiation is harmful to life, damaging DNA and causing sunburn. In addition, NO2 produced in the atmosphere would cause a decrease in visible sunlight reaching the surface and could cause global cooling. Nitric acid rain could stress portions of the biosphere, but the increased nitrate deposition could be helpful to land plants. We have used a two-dimensional atmospheric model to investigate the effects on the Earth's atmosphere of GRBs delivering a range of fluences, at various latitudes, at the equinoxes and solstices, and at different times of day. We have estimated DNA damage levels caused by increased solar UVB radiation, reduction in solar visible light due to NO2 opacity, and deposition of nitrates through rainout of HNO3. In this paper I give a concise review of this work and discuss current and future work on extending and improving our estimates of the terrestrial impact of a GRB.
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