Astronomy:H1821+643
| H1821+643 | |
|---|---|
| Observation data (Epoch J2000.0) | |
| Constellation | Draco |
| Right ascension | 18h 21m 57.2365s |
| Declination | +64° 20′ 36.226″ |
| Redshift | 0.2970 |
| Distance | 3.4 gigalight-years (1.0 Gpc) |
| Type | Quasar |
| 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 ([math]\displaystyle{ \sim 6.3 \times 10^{14} M_\odot }[/math]), 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 [math]\displaystyle{ L_\odot = 10^{47} erg/s }[/math] from the observed X-ray luminosity. [2]
Supermassive Black Hole
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 [math]\displaystyle{ M_{BH} \sim 10^9 M_\odot }[/math]. Kim et al (2004) and Floyd et al (2008) used galactic bulge luminosity fits derived from Hubble data to find [math]\displaystyle{ 10^9 M_\odot }[/math] and [math]\displaystyle{ 3 \times 10^9 M_\odot }[/math] respectively. Russell et al (2010) provided a rough estimate of [math]\displaystyle{ M_{BH} \sim 3 \times 10^9 }[/math]M☉.[2] This was an underestimate with [math]\displaystyle{ \log(\Delta M_{BH}/M_\odot) \geq 1 }[/math]. Kolman et al (1991) and Shapovalova (2016) independently modelled the quasar UV spectrum to find [math]\displaystyle{ M_{BH} \sim 3 \times 10^9 M_\odot }[/math]. Capellupo et al (2017) found [math]\displaystyle{ M_{BH} \sim 3 \times 10^9 }[/math] using [math]\displaystyle{ H\beta }[/math] line emissions. 2 independent X-ray studies found significantly higher values. Reynolds et al (2014) found [math]\displaystyle{ 6\times10^9 M_\odot }[/math] by modelling reflection from the accretion disc and Walker et al found [math]\displaystyle{ 3\times10^{10} M_\odot }[/math] by modelling the interaction of the black hole with the Intracluster medim (ICM) as a Compton-cooled feeding cycle. [math]\displaystyle{ M_{BH} }[/math] is in the range [math]\displaystyle{ \log(M_{BH}/M_\odot) \sim 9.2 - 10.5 }[/math].[2]
The Schwarzschild diameter of this black hole is between 9.4 terametres (63 astronomical unit|AU) and 188 terametres (1,260 astronomical unit|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, [math]\displaystyle{ \sim 1 \% }[/math] the density of air at sea level on Earth.[lower-alpha 1]
Footnotes
References
- ↑ 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. doi:10.1093/mnras/stu1067. Bibcode: 2014MNRAS.442.2809W.
- ↑ 2.0 2.1 2.2 2.3 2.4 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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