A binary super massive black hole in a system has been discovered by an international collaboration of astronomers, which will be a strong aspirant for future recognition of gravitational waves (GWs).
A group of astronomers from various countries like India, Spain, Italy, USA and Argentina are associated in the discovery of binary super massive black hole system. It is a gravitationally lensed blazer named AO 0235+164 using extensive optical photometric observations carried out around the globe during last 4 decades (1982 – 2019). It has been discovered in periodic double-peaked flaring events at an interval of around 8 years, and the separations between two peaks of these flares are around 2 years.
Five such periodic patterns were detected, and it was predicted that the next such flaring event will occur between November 2022 and May 2025. To confirm the next periodic pattern, a global optical photometric monitoring campaign has been initiated under WEBT (Whole Earth Blazar Telescope) consortium. The observational campaign will be led by Dr. Alok C. Gupta, Senior Scientist from Aryabhatta Research Institute of Observational Sciences (ARIES), Nainital. The study was led by Mr. Abhradeep Roy, a Ph.D. student of the Department of High Energy Physics (DHEP), Tata Institute of Fundamental Research (TIFR), Mumbai. The other members of the Indian team include Prof. V. R. Chitnis, Dr. Anshu Chatterjee and Dr. Arkadipta Sarkar from TIFR, Mumbai. The team detected five sets of double-peaked flaring activities during time ranges  January 1982 – October 1984, March 1989 – July 1993, April 1996 – March 2001, June 2006 – June 2009 and May 2014 – May 2017.
The Blazars, which are super massive black holes (SMBH) feeding on gas in the heart of a very distant galaxy, are among the most luminous and energetic objects in the Universe. When the jet, composed of ionized matter traveling at nearly the speed of light, is pointed towards an observer, it is called a blazar. The blazar AO 0235+164 is unique as it is gravitationally lensed by intervening galaxies (phenomenon by which light shining from far away to be bent and pulled by the gravity of an object between its source and the observer).
The blazar AO 0235+164 is the first binary SMBH gravitationally lensed system, which will be a strong candidate of its kind for future detection of gravitational waves (GWs) using the pulsar timing array and future space-based GW detectors. They expect the next such 2 years long flaring episode to happen between November 2022 and May 2025. An intensive multi-wavelength WEBT campaign will be conducted during this period to test the persistence of this apparent nearly-periodic oscillation (QPO) in AO 0235+164.
What is Binary black hole?
A binary black hole is a super-massive black hole system which consists of two black holes in a close orbit and moving around each other. The binary black holes are often divided into a stellar binary black holes which are formed either as remnants of high-mass binary star systems or by dynamic processes. It is believed to be a result of galactic mergers of black holes.
How it occurs:
The Super-massive black-holes are found in binaries, which are believed to form during the mergers of galaxies.
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