Study of Spin Precession Frequencies and Quasi-Periodic Oscillations around Rotating Spacetimes

Abstract

Singularity theorems suggest that under certain conditions, gravitational collapse inevitably leads to a singularity formation. Weak cosmic censorship conjecture proposed by R. Penrose states that singularity is always enclosed within event horizon. Various studies have shown that the gravitational collapse of inhomogeneous matter clouds leads to naked singularity formation. Establishing criteria to distinguish naked singularities and black holes is vital for understanding their physical characteristics. This thesis comprehensively reviews the existing literature and distinguishes between Kerr black holes and naked singularities using spin precession frequency. We also found the constraints on the parameters of the Kerr black hole which were shown to be consistent with the prior studies. Further, we investigate the spin precession frequency of a test gyroscope attached to a stationary observer in a rotating naked singularity spacetime. In the asymptotic limit, Lense-Thirring precession for rotating naked singularity and geodetic precession for null naked singularity are found to be equal to that of a Kerr black hole and a Schwarzschild black hole respectively. In addition, we can distinguish rotating naked singularity and Kerr naked singularity for an observer in the equatorial plane using spin precession. To this end, we have found the constraints on the parameters of rotating naked singularity by employing Monte Carlo Markov Chain simulation and using the observation from five quasi-periodic sources within the relativistic precession model. Our analysis shows that the measurement of spin parameter estimate for GRO J1655-40 is in disagreement with the value found from the continuum-fitting method, while for XTEJ1859+226 and GRS 1915+105, it is inconsistent with spectral analysis results.