球状星团内中等质量黑洞的探测

Detection of Intermediate-Mass Black Holes in Globular Clusters

众所周知,恒星质量黑洞和星系内超大质量黑洞之存在已为学界所公认。另一方面,长期以来,关于球状星团中是否存在质量范围介于上述两类黑洞之间的所谓"中等质量黑洞",则始终争议不断。对于银河系球状星团以及河外星系球状星团内,中等质量黑洞的探测和认识现状做了简要的综述性介绍。

Empirical evidence for both stellar-mass black holes （MBH 〈 102Me） and supermassive black holes （SMBHs, MBH 〉 105Mo） is well established. However, it is not the case for intermediate-mass black hole （IMBHs, 102MQ 〈 MBH 〈 105Me）. It is confirmed that the mass of a SMBH is strongly correlated with the central stellar velocity dispersion （7 of its host galaxy, which is called as the MBH --σ relation. Some people have attempted to extrapolate the relation down the mass scale： the case for central IMBHs in globular clusters, and to detect and discover observationally such black holes, for which cusp clusters are often used as candidates. Different approaches can be taken to search central IMBHs in globular clusters, in- cluding kinematics analyses, star density profile, X-ray and radio detections, among which kinematical approach has been used most frequently. In order to obtain kinematical data for member stars of globular clusters, ground-based/space spectroscopic and astrometric ob- servations should be made, from which line-of-sight velocities and proper motions of cluster members can be obtained respectively. So far as the above issue is concerned, the most researches and discussion have been made for three globular clusters： M15 and wCen in the Milky Way Galaxy and G1 in Andromeda. However, in some decades there have been arguments among different viewpoints for all these three clusters and some other globular clusters. Some people hold that, based on observational facts, there exist central IMBHs in the globular clusters, and others consider these observational facts could be explained equally well by the presence of a concentration of stellar remnants （white dwarfs, neutron stars and stellar-mass black holes） near the cluster center without a massive IMBH. In brief, there has not yet got the unanimous and convincing conclusion about the problem whether central IMBHs in globular clusters exist or not.