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Zeeya Merali: on 5/21/22 at 15:26pm UTC, wrote İzzet Sakallı of Eastern Mediterranean University in Northern Cyprus and...


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June 29, 2022

CATEGORY: Blog [back]
TOPIC: Fingerprints of Invisibles [refresh]
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FQXi Administrator Zeeya Merali wrote on May. 21, 2022 @ 15:26 GMT
İzzet Sakallı of Eastern Mediterranean University in Northern Cyprus and Sara Kanzi of Final International University have published a topical review article, "Greybody Factors and Quasinormal Modes for Black Holes in Various Theories – Fingerprints of Invisibles" in the Turkish Journal of Physics, a scientific journal of Scientific And Technological Research Council Of Turkey, (Turk J Phys (2022) 46: 51 – 103 © TUBİTAK, arXiv preprint (2022).)

From İzzet Sakallı:

Black holes, a generic prediction of Einstein’s General Relativity, are objects of paramount importance both for classical and quantum gravity. Greybody factors and quasinormal modes are two topics related to black hole physics of particular interest. On the one hand, Hawking since it is as a manifestation of a quantum effect in curved spacetime, has always attracted a lot of interest although it has not been detected in the Universe yet. The emitted particles feel an effective potential that back scatters part of the emitted radiation back into the black hole. The greybody factor is a frequency dependent quantity that measures the deviation from the original black body radiation spectrum and provides us with valuable information about the black hole horizon structure. On the other hand, LIGO historical direct detection of gravitational waves from black hole mergers has opened a completely new window to our Universe and allows us to test gravity and probe strong gravitational fields. Consequently, lately there is an increasing interest in black hole perturbations and quasinormal modes of black holes, intimately related to the ring down phase after the formation of the distorted object during the merging of two black holes. When a black hole is perturbed the geometry of spacetime undergoes dumped oscillations, which are characterized by the quasinormal modes with a non-vanishing imaginary part. Chandrasekhar’s famous monograph “The Mathematical Theory of Black Holes” provides us with a comprehensive overview of black hole perturbations.

The study, published April 28 in the Turkish Journal of Physics (doi:10.3906/fiz-2203-15), reviewed the various analytical and numerical methodologies to derive the greybody factors and quasinormal modes of the black holes and black hole like curved spacetimes. The physicists gave specific examples about how one can compute the greybody factors and quasinormal modes. Theoretical findings are also linked to current and possible future observational physics. Stating that it will be a good resource for all physicists interested in these issues, the authors also said that they are going to update their work over the years.

One of the greybody factor results is shown in the figure below:

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