Massive unseen compact companions to hot subluminous stars

中子星和恒星质量的黑洞是大质量恒星在超新星爆炸中结束生命的残余物。探测这些奇异的物体通常只可能在双星系统中，当物质从发光的星星转移到致密的物体时，明亮的X射线从强烈加热的吸积物质中发射出来。然而，在分离的双星系统中，它们只能从可见星星的多普勒反射运动中被探测到。在我们对分离的热亚矮星双星的初步研究中，我们利用了它们的轨道同步性，发现我们的51个样本中至少有3个必须有非常大的质量，但看不见的同伴，即中子星甚至黑洞。这个比例出乎意料的大，因为这些对象被认为是罕见的。我们银河系中数量众多的热亚矮星与大质量致密天体之间的这种新联系可能会导致已知中子星和黑洞数量的巨大增加。然而，我们的分析受到选择效应，这是无法量化的。这只能通过更大的样本来实现。因此，我们已经开始了一项大规模的调查，以寻找热subwarfs与大质量的同伴在一个更大的空间体积比以前。调查的有效目标预选策略确保了对大量同伴的高灵敏度。确凿的证据将是一个高振幅、短周期的双星系统，因为它将排除对伴星性质的任何怀疑。这些结果将揭示出中子星和黑洞作为分离双星中的同伴的种群，以及它们与X射线双星种群的进化联系。该项目还将揭示热次矮星晕群的性质，并允许探测银河系引力势。

Neutron stars and stellar-mass black holes are the remnants of massive stars ending their lifes in supernova explosions. Detecting these exotic objects is usually only possible in a binary, when matter is transferred from the luminous star to the compact object and bright X-rays are emitted from the strongly heated accreted material. In a detached binary, however, they can only be detected from the Dopper-reflex motion of the visible star. In our pilot study of detached hot subdwarf binaries we took advantage of their orbital synchronisation and found that at least three out of our sample of 51 must have very massive, but invisible companions, i.e. neutron stars or even black holes. This fraction is unexpectedly large because these objects are considered to be rare. This new connection between hot subdwarfs, which are numerous in our Galaxy, and massive compact objects may lead to a tremendous increase in the number of known neutron stars and black holes. However, our analysis suffers from selection effects which can not be quantified yet. This can only be achieved by a much larger sample. Therefore, we have initiated a large survey to search for hot subwarfs with massive companions in a much bigger space volume than before. High sensitivity to massive companions is ensured by the survey s efficient target pre-selection strategy. The smoking gun will be a high-amplitude, short-period binary system, because it will exclude any possibility of doubt about the nature of the companion. The results will shed light on the population of neutron stars and black holes as companions in detached binaries and their evolutionary link to the X-ray binary population. The project will also reveal the properties of the halo population of hot subdwarfs and allow the Galactic gravitational potential to be probed.