| Holmberg 15A | |
|---|---|
 Holmberg 15A (in the center) in X-rays by Chandra X-ray Observatory | |
| Observation data (J2000.0 epoch) | |
| Constellation | Cetus |
| Right ascension | 00h 41m 50.5s[1] |
| Declination | −09° 18′ 11″[1] |
| Redshift | 0.055359±0.000016[1] |
| Heliocentric radial velocity | 16,596±5 km/s[1] |
| Galactocentric velocity | 16,653±5 km/s[1] |
| Distance | 787.3 ± 55.12 Mly (241.4 ± 16.9 Mpc)h−1 0.6774 (Comoving)[1] 753 Mly (230.9 Mpc)h−1 0.6774 (Light-travel) |
| Group or cluster | Abell 85 |
| Apparent magnitude (V) | 14.7[1] |
| Characteristics | |
| Type | cD;BrClG[1] |
| Mass | 7×1013[citation needed] M☉ |
| Number of stars | 5×1012[citation needed] |
| Size | 390,570 ly × 218,720 ly (119.75 kpc × 67.06 kpc) (diameter; 25.0 B-mag arcsec−2)[1][a] 386,170 ly × 301,240 ly (118.40 kpc × 92.36 kpc) (diameter; "total" magnitude)[1][a] |
| Apparent size (V) | 1.3′ × 1.2′[1] |
| Other designations | |
| Abell 85-BCG,[1] PGC 2501[1] | |
Holmberg 15A (abbreviated to Holm 15A) is a supergiant elliptical galaxy and the brightest galaxy of the Abell 85 galaxy cluster in the constellation Cetus, about 241.4 megaparsecs (787.3 million light-years) from Earth.[2] It was discovered c. 1937 by Erik Holmberg.[3] It became well known when it was reported to have the largest core ever observed in a galaxy, spanning some 15,000 light years,[3] however this was subsequently refuted.[4][5]
Supermassive black hole
[edit]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☉),[2][3] 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☉[2][3] 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☉.[3] The paper by Lopez-Cruz et al. stated:[3] "Therefore, we conservatively suggest that Holm 15A hosts an SMBH with a mass of 1010 M☉." 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".[3] This makes it one of the most massive black holes ever discovered, with it being classified as an ultramassive black hole.[6]
See also
[edit]Notes
[edit]- ^ a b The quick-look major axis physical diameters given by NED of 106.19 by 59.47 kiloparsecs (346,000 by 194,000 light-years) and 105.00 by 81.90 kiloparsecs (342,000 by 267,000 light-years) were based on a distance estimate of 214.000 ± 45.016 megaparsecs (698.0 ± 146.8 million light-years). The quoted diameters in this infobox were based on NED's provided scale "Virgo + GA + Shapley" of 1.17 kpc/arcsec multiplied by the given angular diameters.
References
[edit]- ^ a b c d e f g h i j k l m "Detailed Information for Object ABELL 0085 BCG". NASA/IPAC Extragalactic Database. Retrieved September 11, 2023.
- ^ a b c "Astronomers Just Found an Absolutely Gargantuan Black Hole The Mass of 40 Billion Suns". 6 August 2019.
- ^ a b c d e f g López-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. S2CID 1140857.
- ^ Bonfini, Paolo; Dullo, Bililign T.; Graham, Alister W. (2015), Too Big to Be Real? No Depleted Core in Holm 15A
- ^ Madrid, Juan P.; Donzelli, Carlos J. (2016), The Abell 85 BCG: A Nucleated, Coreless Galaxy
- ^ Tangermann, Victor (August 6, 2019). "Astronomers Just Discovered One Of The Biggest Black Holes Ever". Futurism.com. Retrieved August 7, 2019.
Further reading
[edit]- K. Mehrgan; J. Thomas; R. Saglia; X. Mazzalay; P. Erwin; R. Bender; M. Kluge; M. Fabricius (24 July 2019). "A 40 Billion Solar-mass Black Hole in the Extreme Core of Holm 15A, the Central Galaxy of Abell 85". The Astrophysical Journal. 887 (2): 195. arXiv:1907.10608. Bibcode:2019ApJ...887..195M. doi:10.3847/1538-4357/ab5856. S2CID 198899965. Measures SMBH mass as (40±8)×109 M☉.
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