Speaker
Description
Small perturbations of spherical symmetric Schwarzschild backgrounds in General Relativity have been already discussed since 1957 by Regge and Wheeler [1] and the quasinormal frequencies of relativistic stars and black holes that emit gravitational waves have been investigated by Nollert [2], Kokkotas and Schmidt [3] as well since 1999. Considering the quite recent detection of gravitational waves in 2015 [4], it is interesting to go back to the topic of quasinormal modes. General Relativity -though a quite successful theory of gravity- is not able to address several issues like the nature of dark matter and dark energy and the accelerated expansion of the universe. Modified theories of gravity appear to be better candidates. We consider in particular the metric teleparallel theory where the gravitational field is not mediated by the curvature as in GR but instead by the torsion [5]. We discuss how we approach the topic of quasinormal modes in this theory following the recent master thesis work by Asuküla [6]. [1] T. Regge and J. A. Wheeler, "Stability of a Schwarzschild Singularity", Phys. Rev. 108, 1063–1069 (1957) [2] K. D. Kokkotas and B. G. Schmidt, "Quasi-Normal Modes of Stars and Black Holes", Living Reviews in Relativity 2 (1999) [3] H.-P. Nollert, "Quasinormal modes: the characteristic ’sound’ of black holes and neutron stars", Classical and Quantum Gravity 16, R159–R216 (1999) [4] B. P. Abbott et al. (LIGO Scientific Collaboration and Virgo Collaboration), "Observation of Gravitational Waves from a Binary Black Hole Merger", Phys. Rev. Lett. 116, 061102 (2016) [5] K. Hayashi and T. Shirafuji, "New general relativity", Phys. Rev. D 19, 3524–3553 (1979) [6] H. Asuküla, "Quasinormal modes of Schwarzschild black holes in 1-parameter New General Relativity" (2021) (Master Thesis, Institute of Physics, University of Tartu)
