Lunch Session LS2  27 June 2022

Quasi-periodic signals from active galactic nuclei

Aims and scope

Search for periodic signals from active galactic nuclei (AGN, especially radio-loud ones) has become widely discussed topic in recent years. Such periodic changes, most likely originating from the innermost regions of the sources, bear imprints of the processes occurring near the central engine, which is mostly inaccessible to our direct view. For the reasons the periodic signals could provide unique diagnostics into various aspect of quasar/blazar studies such as disk-jet connection, magnetic field configuration and, more importantly, strong gravity near the supermassive black holes and release of gravitational waves from the binary supermassive black hole systems. However, a number of challenges associated with searching quasi-periodic oscillations (QPO) in AGN e.g., red-noise dominance, modest significance of the detection and periodic modulation lasting for only a couple of cycles, make it difficult to estimate the true significance of the detection. Moreover, there seems to be no consensus methods that are used to estimate the significance of the QPO features against spurious detection. As a result, it is hard to make meaningful inferences about the nature of the processes thought to be responsible for QPOs. For the reasons, we bring experts in the related fields together to generate a rich discussion the discussion that aims to resolves these issues and pave the way for the further advancement of the field.

Programme

In this session, we plan to cover a broader range of topics related to the quasi-periodic oscillations in AGN including:

  • Red-noise nature of AGN of MWL light curves
  • methods of time series analysis and estimation of significance
  • Several AGN models that can give rise to QPOs
  • origin of high energy emission from from the supermassive binary black hole systems
  • accretions processed around supermassive black holes under extreme gravity leading to QPOs
  • instabilities at the accretion disk and relativistic jet interface leading to QPOs

Invited speakers

Scientific organisers

Gopal Bhatta, Institute of Nuclear Physics, PAN (Co-chair)

Contact

gopal.bhatta @ ifj.edu.pl

Updated on Tue Jan 18 17:19:37 CET 2022