OJ 287

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Observation data (J2000.0 epoch)
OJ 287
Constellation	Cancer
Right ascension	08^h 54^m 48.88^s
Declination	+20° 06′ 30.6″
Redshift	0.307
Distance	3.5 billion
Type	BL Lac object
Apparent magnitude (V)	13–16
See also: Galaxy, List of galaxies

OJ 287 is a BL Lac object, about 18 billion solar masses,^[1] with exceptionally long observational data. Being first apparent on photographic plates from 1891 its lightcurve contains photometric data over 100 years period. This makes it an especially delicate target in extragalactic astronomy. As of 2008, its central supermassive black hole is the largest to have its mass accurately measured, more than six times the value calculated for the previous largest object.^[1]

Optical light curve shows that OJ 287 has a periodic variation of 11-12 years with a narrow double peak at maximum brightness. This kind of variation suggests that an engine is a supermassive binary black hole where a smaller black hole with a mass of only 100 million M_Sun orbits the larger one with an observed 11-12 year orbital period. The maximum brightness is obtained when minor component moves through the accretion disk of the supermassive component at perinigricon.

The mass was calculated by a team led by Mauri Valtonen of Tuorla Observatory in Finland, and the group's results were presented to the public at the 211th meeting of the American Astronomical Society (AAS).^[2] The timing of these outbursts allows the precession of the companion's elliptical orbit to be measured (39° per orbit), which allows the mass of the central black hole to be calculated using Albert Einstein's principles of General relativity (see Kepler problem in general relativity).^[1]

The accuracy of this measurement has been called into question due to the limited number and precision of observed companion orbits, but the calculated value will be further refined using future measurements. The companion's orbit is decaying via the emission of gravitational radiation and it is expected to merge with the central black hole within approximately 10,000 years.^[1]

The study has been published in the Astrophysical Journal.^[3]

[edit] References

^ ^a ^b ^c ^d Shiga, David. "Biggest black hole in the cosmos discovered", NewScientist.com news service, 10 January 2008.
^ "Huge black hole tips the scales", BBC, 2008-01-10. Retrieved on 2008-01-10.
^ Valtonen, M. J.; Lehto, H. J.; Sillanpää, A.; Nilsson, K.; Mikkola, S.; Hudec, R.; Basta, M.; Teräsranta, H.; Haque, S.; Rampadarath, H. (07 2006). "Predicting the Next Outbursts of OJ 287 in 2006-2010". The Astrophysical Journal 646 (1): 36–48. doi:10.1086/504884. .

Valtonen, M. J.; Nilsson, K.; Sillanpää, A.; Takalo, L. O.; Lehto, H. J.; Keel, W. C.; Haque, S.; Cornwall, D.; Mattingly, A. (05 2006). "The 2005 November Outburst in OJ 287 and the Binary Black Hole Model". The Astrophysical Journal 643 (1): L9–L12. doi:10.1086/505039.