# Traces of chaos in gravitational waves from extreme mass ratio inspirals

**Advisor:** Georgios Loukes Gerakopoulos (AI CAS)

**Funding:** Basic scholarship. Additional grant supplement depends on outcome of pending grant application.

**Website:** http://astro.cas.cz/people/georgios-loukes-gerakopoulos

An Extreme Mass Ratio Inspiral (EMRI) consists of a stellar compact object inspiraling into a supermassive black hole while loosing energy and angular momentum due to gravitational radiation reaction. EMRIs are promising targets for the Laser Interferometer Space Antenna (LISA) and will allow us to trace the spacetime around a black hole to an unrepresented accuracy. This tracing will place strict constraints on any deviation from general relativity and the Kerr hypothesis, i.e. the hypothesis that the Kerr metric describes the spacetime around a black hole. To achieve this we need quite accurate gravitational waveform templates in order to extract detailed information from the gravitational waves.

The beginning of the work is to get acquainted with the generation of gravitational waves during an EMRI. The main tool for this will be to numerically solve the Teukolsky equations. These calculations will be performed by using an existing time-domain solver called Teukode and a under development frequency-domain code. During the dissertation, it might be necessary to further develop both codes.

The aim of this work is to investigate gravitational waves from EMRI systems, in which chaos is present. The main focus will be given on EMRIs with a spinning stellar compact object, which can be modeled by a spinning test particle moving in a Kerr background. To study the orbital dynamics of such a body, tools coming from the field of non-linear dynamics will be adopted and employed.

References:

Maggiore, Gravitational Waves (Volume 1):
Theory and Experiments (Oxford University Press, 2008)

Teukolsky,
Astrophysical Journal 185, 635-648 (1973)

Harms, Lukes-Gerakopoulos, Bernuzzi
and Nagar, Physical Review D 93, 044015 (2016)

Barack and Pound, Reports on
Progress in Physics 82, 016904 (2019)

Zelenka, Lukes-Gerakopoulos, Witzany,
Kopacek, Physical Review D 101, 024037 (2020)

Piovano, Maselli , Pani,
Physical Review D 102, 024041 (2020)