标题： 在DESI中寻找从银河系中心弹出的恒星 显示英文标题

标题： Searching for stars ejected from the Galactic Centre in DESI

摘要： 星体与银河系中心（GC）的超大质量黑洞Sgr A*之间的动力学相互作用可能会将星体抛入银河晕中。 尽管最近通过Sgr A*的快速抛射已被识别为高速星体（数百至数千公里/秒），但也预计银河晕中包含较慢的星体，这些星体是在过去数十亿年内被抛射出去的。 在本研究中，我们使用DESI的第一数据发布来寻找这些较慢的GC抛射物，这些抛射物因其综合的高金属度（${\rm [Fe/H]}\gtrsim0$）和垂直角动量的小值（$L_Z$）而应从星体晕群体中突出，其分布应在零处达到峰值。 我们的搜索没有得到检测结果，但使我们能够对过去约5 Gyr内GC抛射星体的速率设定上限为$\sim2.8\times10^{-3}$yr$^{-1}$，这一结果与抛射模型无关。 这意味着我们的结果可以用于对不同的抛射模型施加限制，包括那些涉及Sgr A*在过去数十亿年内与其他大质量黑洞合并的模型。 显示英文摘要

摘要： Dynamical interactions between stars and the super massive black hole Sgr A* at the Galactic Centre (GC) may eject stars into the Galactic halo. While recent fast ejections by Sgr A* have been identified in the form of hypervelocity stars (hundreds to thousands km/s), it is also expected that the stellar halo contains slower stars, ejected over the last few billion years. In this study, we use the first data release of DESI to search for these slower GC ejecta, which are expected to stand out from the stellar halo population for their combined high metallicity (${\rm [Fe/H]}\gtrsim0$) and small values of their vertical angular momentum ($L_Z$), whose distribution should peak at zero. Our search does not yield a detection, but allows us to place an upper limit on the ejection rate of stars from the GC of $\sim2.8\times10^{-3}$ yr$^{-1}$ over the past ~5 Gyr, which is ejection model independent. This implies that our result can be used to put constraints on different ejection models, including that invoking mergers of Sgr A* with other massive black holes in the last last few billion years.