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H1821+643

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H1821+643
Chandra X-ray Observatory image of H1821+643
Observation data (Epoch J2000.0)
ConstellationDraco
Right ascension18h 21m 57.2365s
Declination+64° 20′ 36.226″
Redshift0.2970
Distance3.4 gigalight-years (1.0 Gpc)
TypeQuasar
Apparent magnitude (V)14.24
See also: Quasar, List of quasars

H1821+643 is an extraordinarily luminous, radio-quiet quasar in the constellation of Draco. [1] The associated Active Galactic Nucleus (AGN) is situated in the Brightest Central Galaxy (BCG) of a massive (), strong cooling flow cluster, CL 1821+64.[2] Russel et al (2010) spatially isolated its X-ray signal from the surrounding cluster in Chandra X-ray observatory observations and computed from the observed X-ray luminosity. [2]

Supermassive Black Hole

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The SMBH centred in CL 1821+64 is believed to be among the most massive in the known Universe.[2] A variety of techniques have found different values for the mass. 5 studies found values . Kim et al (2004) and Floyd et al (2008) used galactic bulge luminosity fits derived from Hubble data to find and respectively. Russell et al (2010) provided a rough estimate of M.[2] This was an underestimate with . Kolman et al (1991) and Shapovalova (2016) independently modelled the quasar UV spectrum to find . Capellupo et al (2017) found using line emissions. 2 independent X-ray studies found significantly higher values. Reynolds et al (2014) found by modelling reflection from the accretion disc and Walker et al found by modelling the interaction of the black hole with the Intracluster medium (ICM) as a Compton-cooled feeding cycle. is in the range .[2]

The Schwarzschild diameter of this black hole is between 9.4 terametres (63 AU) and 188 terametres (1,260 AU), which is about 16 times the diameter of Pluto's orbit. If the hole were a Euclidean sphere, the average density would be 18 g/m3, the density of air at sea level on Earth.[a]

Footnotes

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  1. ^ Mass 3.0×1010 * 2.0×1030=6.0×1040 kg. Volume at radius 8.6×1013 m is 2.66×1042 m3.

References

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  1. ^ Walker, S. A.; Fabian, A. C.; Russell, H. R.; Sanders, J. S. (2014). "The effect of the quasar H1821+643 on the surrounding intracluster medium: Revealing the underlying cooling flow". Monthly Notices of the Royal Astronomical Society. 442 (3): 2809. arXiv:1405.7522. Bibcode:2014MNRAS.442.2809W. doi:10.1093/mnras/stu1067.
  2. ^ a b c d e Sisk-Reynés, J.; Reynolds, C. S.; Matthews, J. H.; Smith, R. N. (2022). "Evidence for a moderate spin from X-ray reflection of the high-mass supermassive black hole in the cluster-hosted quasar H1821+643". arXiv:1405.7522.
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