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arXiv 2103.10593astro-ph.SRastro-ph.EP
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利用\textit{Gaia}资料建立质量-速度频散关系及其对解释短持续和简并微透镜事件的作用

Mass-velocity dispersion relation by using the \textit{Gaia} data and its effect on interpreting short-duration and degenerate microlensing events

Sedighe Sajadian, Sohrab Rahvar, Fatemeh Kazemian

摘要:

引力微透镜,即银河系中的恒星与其他恒星之间的透镜效应,已被用于探索致密的暗物质、系外行星和黑洞。微透镜事件的持续时间,即所谓的爱因斯坦穿越时间,是透镜物体的距离、质量和速度的函数。不同年龄和质量的透镜在星系内可能有不同的特征速度,这可能导致我们对微透镜事件的误解。在这项工作中,我们使用\gaia ~存档的数据,找到速度色散和质量之间的关系,和恒星的年龄。这种质量-速度频散关系证实了已知的早期型和大质量恒星的年龄-速度关系,并在$2$ - $3$ sigma水平上揭示了低质量和晚期型恒星的恒星速度频散对质量的依赖性。通过考虑这种相关性,我们模拟短时间微透镜事件由于褐矮星。从这个模拟中,我们得出结论,晶状体质量被低估的$\sim 2.5$ - $5.5\%$,而建模短时间和退化的微透镜事件与贝叶斯分析。

英文摘要:

Gravitational microlensing, the lensing of stars in the Milky Way galaxy with other stars, has been used for exploring compact dark matter objects, exoplanets, and black holes. The duration of microlensing events, the so-called Einstein crossing time, is a function of distance, mass, and velocities of lens objects. Lenses with different ages and masses might have various characteristic velocities inside the galaxy and this might lead to our misinterpretation of microlensing events. In this work, we use the \gaia~archived data to find a relation between the velocity dispersion and mass, and the age of stars. This mass-velocity dispersion relation confirms the known age-velocity relation for early-type and massive stars, and additionally reveals a dependence of stellar velocity dispersion on the mass for low-mass and late-type stars at $2$-$3$ sigma level. By considering this correlation, we simulate short-duration microlensing events due to brown dwarfs. From this simulation, we conclude that lens masses are underestimated by $\sim 2.5$-$5.5\%$ while modeling short-duration and degenerate microlensing events with the Bayesian analysis.

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