标题： 宇宙天体电离辐射与地球：间歇性强烈源的简要综述和统计 显示英文标题

标题： Astrophysical Ionizing Radiation and the Earth: A Brief Review and Census of Intermittent Intense Sources

摘要： 宇宙辐射背景对生命是一种限制，它们的分布将影响银河系宜居带。 地球上的生命是在这些背景条件下发展的，表征事件发生率将阐明其重要影响。 反过来，这可以作为与其他潜在有生命的行星进行比较的基础。 在本综述中，我们估计了由天体物理实体产生的各种强烈辐射爆发的强度和发生率，这些实体从宇宙距离的伽马射线暴到太阳本身。 其中许多对生物圈构成潜在威胁：在与人类历史相比时间尺度较长的情况下，发生足以破坏陆地或海洋生命事件的概率变得很大。 我们列举了已知的辐射源，并表征了它们在地球上的强度以及这些量的速率或上限。 在可能的情况下，我们估计了一个“致死间隔”，即根据目前的知识状态，重大灭绝级别事件发生的概率；我们的估计基于计算或预期的平流层臭氧耗竭。 一般来说，中等水平的事件主要由太阳主导，但更严重且不常发生的事件可能主要由伽马射线暴和超新星主导。 我们首次指出所谓的“短而硬”伽马射线暴是一个相当大的威胁，其规模与超新星相当，大于大多数过去研究中考虑的高光度长爆发。 鉴于它们的前兆，短爆发可能会几乎没有或完全没有预警。 显示英文摘要

摘要： Cosmic radiation backgrounds are a constraint on life, and their distribution will affect the Galactic Habitable Zone. Life on Earth has developed in the context of these backgrounds, and characterizing event rates will elaborate the important influences. This in turn can be a base for comparison with other potential life-bearing planets. In this review we estimate the intensities and rates of occurrence of many kinds of strong radiation bursts by astrophysical entities ranging from gamma-ray bursts at cosmological distances to the Sun itself. Many of these present potential hazards to the biosphere: on timescales long compared with human history, the probability of an event intense enough to disrupt life on the land surface or in the oceans becomes large. We enumerate the known sources of radiation and characterize their intensities at the Earth and rates or upper limits on these quantities. When possible, we estimate a "lethal interval", our best estimate of how often a major extinction-level event is probable given the current state of knowledge; we base these estimates on computed or expected depletion of stratospheric ozone. In general, moderate level events are dominated by the Sun, but the far more severe infrequent events are probably dominated by gamma-ray bursts and supernovae. We note for the first time that so-called "short-hard" gamma-ray bursts are a substantial threat, comparable in magnitude to supernovae and greater than that of the higher-luminosity long bursts considered in most past work. Given their precursors, short bursts may come with little or no warning.