Geodetic Motion Around Rotating Blackhole in Nonlocal Gravity

Blackhole in Nonlocal Gravity: Comparing Metric from Newmann-Janis Algorithm with Slowly Rotating Solution

The strong gravitational field near massive blackhole is an interesting regime to test General Relativity(GR) and modified gravity theories. The knowledge of spacetime metric around a blackhole is a primary step for such tests. Solving field equations for rotating blackhole is extremely challenging task for the most modified gravity theories. Though the derivation of Kerr metric of GR is also demanding job, the magical Newmann-Janis algorithm does it without actually solving Einstein equation for rotating blackhole. Due to this notable success of Newmann-Janis algorithm in the case of Kerr met…

Nonlocal star as a blackhole mimicker

In the context of ghost-free, infinite derivative gravity, we will provide a quantum mechanical framework in which we can describe astrophysical objects devoid of curvature singularity and event horizon. In order to avoid ghosts and singularity, the gravitational interaction has to be nonlocal, therefore, we call these objects as nonlocal stars. Quantum mechanically a nonlocal star is a self-gravitational bound system of many gravitons interacting nonlocally. Outside the nonlocal star the spacetime is well described by the Schwarzschild metric, while inside we have a non-vacuum spacetime metri…

Modified Gravity Corrections in Fundamental Orbital Frequencies in Kerr Spacetime

As a first step towards the calculation of waveform of Extreme Mass Ratio Inspirals for Modified Gravity theories, we calculate the orbital frequencies of a Small Compact Object inspiralling into a super massive blackhole for a Nonlocal gravity model. The small compact object moves along an orbit which can be approximated to a geodesic of the background spacetime due to large mass ratio of central blackhole to Small Compact Object. In General Relativity, the fundamental orbital frequencies $Ω_r,\;Ω_θ$ and $Ω_ϕ$ can be calculated by solving geodesic equations of the Kerr metric. If we formulate…

Quantum structure of spacetime and blackhole entropy

The gap between a microscopic theory for quantum spacetime and the semiclassical physics of blackholes is bridged by treating the blackhole spacetimes as highly excited states of a class of nonlocal field theories. All the blackhole thermodynamics is shown to arise from asymptotic form of the dispersion relation satisfied by the elementary excitations of these field theories. These models involve, quite generically, fields which are: (i) smeared over regions of the order of Planck length and (ii) possess correlation functions which have universal short distance behaviour.

太阳系实验对非局域引力的约束

Solar-system experimental constraints on nonlocal gravity

利用恒星光偏转、夏皮罗时间延迟等四类高精度太阳系实验，研究Deser-Woodard非局域引力模型参数$(ζ,b)$的约束，明确参数空间允许区域并揭示各实验的约束特性。