标题： 使用Gaia DR3和VLT/FORS2光谱学寻找新的超高速星 显示英文标题

标题： Searching for new Hypervelocity Stars with Gaia DR3 and VLT/FORS2 Spectroscopy

摘要： 高速恒星是独特天体，在银河系中以超过本地逃逸速度的速度运动，为研究银河系引力势和其中心超大质量黑洞的特性提供了有价值的见解。盖亚DR3的出现提供了前所未有的天体测量精度，使得发现新的高速恒星并促进其特征分析成为可能。本研究旨在利用盖亚DR3数据识别和表征高速恒星候选者，重点关注缺乏径向速度测量的恒星。我们的目标是估计这些恒星的总速度，并在可能的情况下确定它们在银河系框架内的起源。我们对盖亚DR3数据应用了严格的选择标准，重点关注视差不确定性较低且天体测量保真度高的源。得到了银河系静止参考系中总速度的分布，并用于识别候选者。使用VLT/FORS2进行光谱后续观测，为这些候选者的一部分提供了径向速度测量。我们评估了在不同银河系势模型下恒星超过本地逃逸速度的概率，并追踪它们的过去轨道以确定可能的起源。从盖亚DR3中，我们识别出149个高速恒星候选者，其Pesc超过本地逃逸速度的50%。我们对其中23个源的后续光谱观测确认，所选目标正在以高速运动，许多似乎取决于采用的银河系势而逃离银河系。我们的分析表明，近三分之一的恒星可能具有银河系外的起源。这些发现突显了需要更精确的天体测量和光谱数据，以明确确定高速恒星的起源并改进银河系势模型。 显示英文摘要

摘要： Hypervelocity stars are unique objects moving through the Milky Way at speeds exceeding the local escape velocity, providing valuable insights into the Galactic gravitational potential and the properties of its central supermassive black hole. The advent of Gaia DR3 offers an unprecedented astrometric precision, enabling the discovery of new hypervelocity stars and facilitating their characterization. This study seeks to identify and characterize hypervelocity star candidates using Gaia DR3 data, focusing on stars lacking radial velocity measurements. Our goal was to estimate the total velocities of these stars and establish their origin within the Galactic framework, if possible. We applied strict selection criteria to Gaia DR3 data, focusing on sources with low parallax uncertainties and high astrometric fidelity. The distributions of the total velocities in the Galactic rest frame were derived and used to identify candidates. Spectroscopic follow-up with VLT/FORS2 provided radial velocity measurements for a subset of these candidates. We evaluated the probabilities of stars exceeding local escape velocities under different Galactic potential models and traced their past orbits to identify possible origins. From Gaia DR3, we identified 149 hypervelocity star candidates with Pesc > 50% of exceeding local escape velocities. Our follow-up spectroscopy for 23 of those sources confirms that the selected targets are traveling at high velocities, with many appearing to escape the Galaxy, depending on the Galactic potential adopted. Our analysis suggests that nearly one-third of the stars may have an extra-Galactic origin. These findings highlight the need for more precise astrometric and spectroscopic data to conclusively determine the origins of hypervelocity stars and improve models of the Galactic potential.