Experimental Particle and Astro-Particle Physics Seminar

Stefanos Leontsinis (Universitaet Zuerich (CH))


Blazars are active galactic nuclei with relativistic jets. They are highly variable sources, often undergoing rapid and dramatic fluctuations in brightness and these outbursts are very difficult to predict. However, certain observed outbursts from an exceptional Blazar OJ 287 can be explained due to the presence of a massive black hole(BH) binary in its central region. Detailed General Relativistic modeling allowed us to predict major optical outbursts during September 2007, November 2015 and finally during 31, July 2019. Multi-wavelength observational campaigns confirmed occurrences of secondary BH impact-induced bremsstrahlung flares from OJ 287 in these epochs.

I will detail how these efforts  allowed us to establish the presence of a spinning supermassive black hole binary that spirals in due to the emission of nano-Hertz gravitational waves in the central engine of OJ287. Our on-going efforts, relevant to both the Event Horizon Telescope consortium and the International Pulsar Timing Array consortium for detecting GWs from such massive BH systems in the coming years, will be listed. These efforts should be helpful to inaugurate the era of persistent multi-messenger nano-Hz GW astronomy in the SKA,ngEHT and KM3NeT era.

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Zoom room link

Meeting ID: 912 1383 7955
Passcode: 069577

    • 2:00 PM 3:00 PM
      Blazar OJ287 and its nano-Hertz GW emitting massive Black Hole binary central engine 1h
      Speaker: A. Gopakumar (TIFR, Mumbai)