It is now well-established that a dark, compact object, very likely a massive black hole (MBH) of around four million solar masses is lurking at the centre of the Milky Way. While a consensus is emerging about the origin and growth of supermassive black holes (with masses larger than a billion solar masses), MBHs with smaller masses, such as the one in our galactic centre, remain understudied and enigmatic. The key to understanding these holes—how some of them grow by orders of magnitude in mass—lies in understanding the dynamics of the stars in the galactic neighbourhood. Stars interact with the central MBH primarily through their gradual inspiral due to the emission of gravitational radiation. Also stars produce gases which will subsequently be accreted by the MBH through collisions and disruptions brought about by the strong central tidal field. Such processes can contribute significantly to the mass of the MBH and progress in understanding them requires theoretical work in preparation for future gravitational radiation millihertz missions and X-ray observatories. In particular, a unique probe of these regions is the gravitational radiation that is emitted by some compact stars very close to the black holes and which could be surveyed by a millihertz gravitational-wave interferometer scrutinizing the range of masses fundamental to understanding the origin and growth of supermassive black holes. By extracting the information carried by the gravitational radiation, we can determine the mass and spin of the central MBH with unprecedented precision and we can determine how the holes “eat” stars that happen to be near them.

现在已经确定的是，银河系中心潜伏着一个黑暗致密的物体，很可能是一个质量约为 400 万个太阳质量的大质量黑洞 (MBH)。虽然关于超大质量黑洞（质量超过十亿个太阳质量）的起源和生长的共识正在形成，但质量较小的MBH（例如我们银河系中心的黑洞）仍然未被充分研究且神秘莫测。了解这些空洞（其中一些空洞的质量如何以数量级增长）的关键在于了解银河系附近恒星的动力学。恒星与中央MBH的相互作用主要是通过由于引力辐射的发射而逐渐吸气。恒星也会产生气体，这些气体随后会通过强烈的中央潮汐场带来的碰撞和破坏而被MBH吸积。这些过程可以对MBH的质量做出重大贡献，并且在理解它们方面取得进展需要为未来的引力辐射毫赫兹任务和X射线天文台做准备的理论工作。特别是，这些区域的独特探测器是一些非常靠近黑洞的致密恒星发出的引力辐射，可以通过毫赫兹引力波干涉仪进行测量，仔细检查质量范围，这对于理解起源和生长至关重要超大质量黑洞。通过提取引力辐射携带的信息，我们可以以前所未有的精度确定中心MBH的质量和自旋，并且可以确定这些黑洞如何“吃掉”恰好在它们附近的恒星。