标题： 利用微透镜探测孤立的致密遗迹 显示英文标题

标题： Probing isolated compact remnants with microlensing

摘要： 我们研究了孤立的致密遗迹（ICoRs），即那些不处于双星系统中的中子星和黑洞，因此无法作为X射线双星被探测到。 ICoRs可能占银河系恒星质量预算的$\sim\,5$百分比，但它们非常难以探测。 在这里，我们探讨了利用微引力透镜来识别ICoRs的可能性。 在之前的一篇文章中，我们描述了考虑前身分布和形成时反冲的情况下，银河系相空间中中子星演化的模拟。 在这里，我们首先重新考虑中子星和黑洞的演化与分布，并加入了一个核球成分。 从新的分布中，我们计算了微引力透镜光学深度、事件率以及事件时间尺度的分布，比较并对比了ICoRs和“普通恒星”的情况。 我们发现，由于银河系中的蒸发效应，遗迹对光学深度的贡献略微低于无运动学的情况。另一方面，对事件率的相对贡献高出一个因子$\sim\,5$。 总体而言，$\sim\,6-7$百分比的事件可能与ICoRs相关。 特别是，$\sim\,30-40$百分比的持续时间为$>\,100$天的事件可能与黑洞有关。 因此，似乎微引力透镜观测是一种适合探测银河系ICoRs群体的工具。 显示英文摘要

摘要： We consider isolated compact remnants (ICoRs), i.e. neutrons stars and black holes that do not reside in binary systems and therefore cannot be detected as X-ray binaries. ICoRs may represent $\sim\,5$ percent of the stellar mass budget of the Galaxy, but they are very hard to detect. Here we explore the possibility of using microlensing to identify ICoRs. In a previous paper we described a simulation of neutron star evolution in phase space in the Galaxy, taking into account the distribution of the progenitors and the kick at formation. Here we first reconsider the evolution and distribution of neutron stars and black holes adding a bulge component. From the new distributions we calculate the microlensing optical depth, event rate and distribution of event time scales, comparing and contrasting the case of ICoRs and "normal stars". We find that the contribution of remnants to optical depth is slightly lower than without kinematics, owing to the evaporation from the Galaxy. On the other hand, the relative contribution to the rate of events is a factor $\sim\,5$ higher. In all, $\sim\,6-7$ percent of the events are likely related to ICoRs. In particular, $\sim\,30-40$ percent of the events with duration $>\,100$ days are possibly related to black holes. It seems therefore that microlensing observations are a suitable tool to probe the population of Galactic ICoRs.