ESO 444-46 (Shapley 8-1, A3558-M1 or ESO 444-G 046) is a class E4 supergiant elliptical galaxy; the dominant and brightest member of the Abell 3558 galaxy cluster around away in the constellation Centaurus. It lies within the core of the massive Shapley Supercluster (Shapley Concentration), one of the closest neighboring superclusters. It is one of the largest galaxies in the local universe, and possibly contains one of the most massive black holes known. The black hole's mass is very uncertain of solar masses (), (with estimates ranging from as low as , to as high as ) based on the break radius of the host galaxy.
Physical characteristics
Globular clusters
ESO 444-46 has an estimated population of about 27,000 globular clusters which may be one of the largest populations ever studied. This is in contrast to 15,000 globular clusters in Messier 87 (M87), and 200 in the Milky Way. However, this large number may be due to the addition of Intracluster globular clusters since the galaxy lies about 1 arcmin of the center of Abell 3558.
Supermassive black hole
A calculation using the spheroidal luminosity method (Lsph) by estimating the stellar density of the central region using its brightness, yielded an initial mass of (1010.89 ± 0.54) (with the range being to ) (1010.35 to 1011.43). This would make it one of the most massive black holes known – nearly twelve times the mass of the black hole in Messier 87 (M87*), and 18,000 times more massive than Sagittarius A* (Sgr A*), the Milky Way's central black hole. A black hole of this mass has a Schwarzschild radius of 1,531 (with the range being 868.6 to 10,660) AU (about 458 billion km (with the range being 130 billion km to 1.59 trillion km) in diameter) or 102 (with the range being 28.8 to 354.8) times the distance between Neptune and the Sun.
Alternative calculations using the M-sigma relation (Mσ) and the newer core break radius method (Rb) yielded estimates of (108.70 ± 0.41) and (1010.43 ± 0.44), respectively.
See also List of galaxies List of nearest galaxies List of NGC objects (4001–5000) List of spiral galaxies NGC 4889 NGC 4874 IC 1101 ESO 383-76
Notes
References
External links