Theoretical Research On IR Modified Horava Gravity

Recently, based on the Lifshitz scale Horava proposed an ultraviolet complete gravity theory. In order to realize renormalizability, this theory abandons Lorentz symmetry which leads to introduce the high derivatives of metric in the UV region. Hence a nonrelativistic power-counting renormalizable gravity is obtained, which is named Horava-Lifshitz (HL) gravity. On the other hand if we want to obtain a Minkowski vacuum in the IR region, we have to deform original HL theory with a relevant operator proportional to the Ricci scalar of the Three-geometry. This idea is proposed firstly by Kehagias-Sfetsos (KS) who obtain a spherically symmetric black hole solution in asymptotically flat spacetime. This solution is also named KS black hole in IR modified Horava gravity which will be discussed in this dissertation.In this paper, we discuss some important attribute property of KS black hole including Hawking radiation, quasinormal modes, light deflection and quantum statistical entropy.In chapter1, we present the background need in this paper which are contained the black hole and Horava gravity.In chapter2, Hawking radiation spectrums at event horizon are obtained firstly by the geodesic method. Our results show that the real spectrums deviate from the pure spectrum which have nothing to do with particle mass. Then, the tunneling rate of fermions at the horizon is analyzed by complex path method. The relationship between the tunneling rate and Hawking temperature are obtained as well.In chapter3, the lower-lying QNM frequencies of fermions field are calculated by the method of third and sixth order WKB approximations, respectively. Results show that for a given gravitational parameter a and angular momentum number k, when the mode number n increases, the oscillating frequency decreases and the damping frequency increases. If we fixed k and n, with the increasing parameter a, the oscillating rate decreases and the damping rate increases also. So comparing usual Schwarzschild black hole, the fermions field in KS black hole will live longer.In chapter4, we use the action analysis of Lagrange method, the analytic expression of light deflection angle is derived in KS black hole. Considering the astronomical observation including long-baseline radio interferometer, Jupiter measurement, Hipparcos satellite, we get the constraints of alpha in solar, Jupiter and Earth systems.In chapter5, the quantum statistical entropies in KS black hole are investigated by Generalized Uncertainty Principle method and't Hooft's Brick wall method, respectively. The results show that if one chooses a suitable ergosphere's thickness or adjusts a right cut-off factor, the entropy can restore the Bekenstein area spectrum.All above results help us to find KS black hole and supply the abundant referenced data to study further KS black hole. This paper also sheds light on the understand of Horava gravity.