OJ 287

OJ 287 is a BL Lac object located 3.5 billion light-years away that has produced quasi-periodic optical outbursts going back approximately 120 years, as first apparent on photographic plates from 1891. Seen on photographic plates since at least 1887,[3] it was first detected at radio wavelengths during the course of the Ohio Sky Survey. It is a supermassive black hole binary.[4] The intrinsic brightness of the flashes corresponds to over a trillion times the Sun's luminosity, greater than the entire Milky Way galaxy's light output.[5]

OJ 287
Comparisons of large and small black holes in galaxy OJ 287 to the Solar System
Observation data (Epoch J2000)
ConstellationCancer
Right ascension08h 54m 48.9s[1]
Declination+20° 06′ 31″[1]
Redshift0.306000 [1]
Distance3.5 Gly (1.073 Gpc)
TypeBL Lac[1]
Apparent magnitude (V)15.43[2]
Other designations
EGO 0851+202,[1] 3EG J0853+1941,[1] RGB J0854+201[1]
See also: Quasar, List of quasars

Characteristics

Its central supermassive black hole is among the largest known, with a mass of 18.35 billion solar masses,[6][4] more than six times the value calculated for the previous largest object.[7] Its Schwarzschild radius is ~362 AU,[8] about 12 and 0.75 times the semimajor axes of the orbits of Neptune and dwarf planet Sedna, respectively.

The optical light curve shows that OJ 287 has a periodic variation of 11–12 years with a narrow double peak at maximum brightness.[9] This kind of variation suggests that it is a binary supermassive black hole.[10] The double-burst variability is thought to result from the smaller black hole punching through the accretion disc of the larger black hole twice in every 12 years.[5]

The smaller supermassive black hole with a mass of "only" 150 million M☉[4] orbits the larger one with an observed orbital period of ~12 years and a calculated eccentricity of ~0.65.[4] The maximum brightness is obtained when the minor component moves through the accretion disk of the supermassive component at perinigricon. The perinigricon and aponigricon of its orbit are ~3,250 and ~17,500 AU, or about 9 and 48 times the primary's Schwarzschild radius;[8] the latter is also ~0.275 light-year and ~0.085 parsec.

The mass was calculated in 2008 by a team led by Mauri Valtonen of Tuorla Observatory in Finland.[11] 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 Einstein's principles of general relativity (see Kepler problem in general relativity).[7] The timings also provide a test of the black hole no-hair theorem, which so far is consistent with the results.[5][4]

In order to reproduce all the known outbursts, the rotation of the primary black hole has to be 38% of the maximum allowed rotation for a Kerr black hole.[12][4]

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.[7][13][8]

References
  1. "NED results for object OJ +287". NASA/IPAC Extragalactic Database. Retrieved 2008-07-10.
  2. "QSO J0854+2006". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 15 March 2018.
  3. Camille M. Carlisle (13 January 2015). "Black Hole Binary En Route to Merger?". Sky & Telescope.
  4. Laine, S.; Dey, L.; Valtonen, M.; Gopakumar, A.; Zola, S.; Komossa, S.; Kidger, M.; Pihajoki, P.; Gómez, J.L.; Caton, D.; Ciprini, S.; Drozdz, M.; Gazeas, K.; Godunova, V.; Haque, S.; Hildebrandt, F.; Hudec, R.; Jermak, H.; Kong, A.K.H.; Lehto, H.; Liakos, A.; Matsumoto, K.; Mugrauer, M.; Pursimo, T.; Reichart, D.E.; Simon, A.; Siwak, M.; Sonbas, E. (2020). "Spitzer Observations of the Predicted Eddington Flare from Blazar OJ 287" (PDF). The Astrophysical Journal. 894 (1): L1. doi:10.3847/2041-8213/ab79a4. S2CID 216562421.
  5. "Spitzer Telescope Reveals the Precise Timing of a Black Hole Dance". JPL.NASA.gov. Jet Propulsion Laboratory. 28 April 2020. Retrieved 2020-05-03.
  6. Valtonen, M. J.; Lehto, H. J.; Nilsson, K.; et al. (2008). "A massive binary black-hole system in OJ 287 and a test of general relativity" (PDF). Nature. 452 (7189): 851–853. arXiv:0809.1280. Bibcode:2008Natur.452..851V. doi:10.1038/nature06896. PMID 18421348. S2CID 4412396.
  7. Shiga, David (10 January 2008). "Biggest black hole in the cosmos discovered". NewScientist.com news service.
  8. Dey, L.; Gopakumar, A.; Valtonen, M.; Zola, S.; Susobhanan, A.; Hudec, R.; Pihajoki, P.; Pursimo, T.; Berdyugin, A.; Piirola, V.; Ciprini, S.; Nilsson, K.; Jermak, H.; Kidger, M.; Komossa, S. (2019). "The Unique Blazar OJ 287 and Its Massive Binary Black Hole Central Engine". Universe. 5 (5): 108. arXiv:1905.02689. doi:10.3390/universe5050108. S2CID 146808185.
  9. Shi, Weizhao; Liu, Xiang; Song, Huagang (2007). "A new model for the periodic outbursts of the BL Lac object OJ287". Astrophysics and Space Science. 310 (1–2): 59–63. Bibcode:2007Ap&SS.310...59S. doi:10.1007/s10509-007-9413-z. S2CID 121149840.
  10. Valtonen, M. J.; Nilsson, K.; Sillanpää, A.; et al. (2006). "The 2005 November Outburst in OJ 287 and the Binary Black Hole Model". The Astrophysical Journal. 643 (1): L9–L12. Bibcode:2006ApJ...643L...9V. doi:10.1086/505039.
  11. "Huge black hole tips the scales". BBC. 2008-01-10. Retrieved 2008-01-10.
  12. Valtonen, M. J.; Mikkola, S.; Merritt, D.; et al. (February 2010). "Measuring the Spin of the Primary Black Hole in OJ287". The Astrophysical Journal. 709 (1): 725–732. arXiv:0912.1209. Bibcode:2010ApJ...709..725V. doi:10.1088/0004-637X/709/2/725. S2CID 119276181.
  13. Valtonen, M. J.; Lehto, H. J.; Sillanpaa, A.; et al. (2006). "Predicting the Next Outbursts of OJ 287 in 2006–2010". The Astrophysical Journal. 646 (1): 36–48. Bibcode:2006ApJ...646...36V. doi:10.1086/504884..

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