It has been postulated that the primary component of the galactic core is a supermassive black hole with a mass of 40 billion solar masses (M☉),[1][2] although no direct measurement has yet been made. Previous estimates by Lauer et al. have jointed a mass value as high as 310 billion M☉[1][2] using the gamma ray point break radius method. Kormendy and Bender gave a value of 260 billion M☉ in a 2009 paper. Lower estimates were given by Kormendy and Ho et al. in 2013 at 2.1 and 9.2 billion M☉.[2] The paper by Lopez-Cruz et al. stated:[2] "Therefore, we conservatively suggest that Holm 15A hosts an SMBH with a mass of ~1×1010M☉." Kormendy and Ho et al derived these equations using the M–sigma relation and the size of the outer bulge of the galaxy, which are indirect estimates. Rusli et al derived a value of 170 billion M☉ using break radius methodology. In addition, Abell 85 has its velocity dispersion of dark matter halo at ~750 km/s, which could be explained only by a black hole with a mass greater than 150 billion M☉, although Kormendy and Ho et al stated that "dark matter halos are scale-free, and the SMBH-dark matter coevolution is independent from the effects of baryons".[2] This makes it one of the most massive black holes ever discovered, with it being classified as an ultramassive black hole.[5]
^ abcdefgLópez-Cruz, O.; Añorve, C.; Birkinshaw, M.; Worrall, D. M.; Ibarra-Medel, H. J.; Barkhouse, W. A.; Torres-Papaqui, J. P.; Motta, V. (2014). "The Brightest Cluster Galaxy in Abell 85: The Largest Core Known So Far". The Astrophysical Journal. 795 (2): L31. arXiv:1405.7758. Bibcode:2014ApJ...795L..31L. doi:10.1088/2041-8205/795/2/L31. S2CID1140857.
