A note on Harmonic Gauge(s) in Massive Gravity

The Effect of Higher Harmonic Corrections on the Detection of massive black hole binaries with LISA

Massive black hole binaries are key targets for the space based gravitational wave interferometer LISA. Several studies have investigated how LISA observations could be used to constrain the parameters of these systems. Until recently, most of these studies have ignored the higher harmonic corrections to the waveforms. Here we analyze the effects of the higher harmonics in more detail by performing extensive Monte Carlo simulations. We pay particular attention to how the higher harmonics impact parameter correlations, and show that the additional harmonics help mitigate the impact of having tw…

A note on "symmetric" vielbeins in bimetric, massive, perturbative and non perturbative gravities

We consider a manifold endowed with two different vielbeins $E^{A}{}_μ$ and $L^{A}{}_μ$ corresponding to two different metrics $g_{μν}$ and $f_{μν}$. Such a situation arises generically in bimetric or massive gravity (including the recently discussed version of de Rham, Gabadadze and Tolley), as well as in perturbative quantum gravity where one vielbein parametrizes the background space-time and the other the dynamical degrees of freedom. We determine the conditions under which the relation $g^{μν} E^{A}{}_μ L^{B}{}_ν = g^{μν} E^{B}{}_μ L^{A}{}_ν$ can be imposed (or the "Deser-van Nieuwenhuize…

Note on the thermal history of decoupled massive particles

This note provides an alternative approach to the momentum decay and thermal evolution of decoupled massive particles. Although the ingredients in our results have been addressed in Ref.\cite{Weinberg}, the strategies employed here are simpler, and the results obtained here are more general.

A note on the pp-wave solution of Minimal Massive 3D Gravity coupled with Maxwell-Chern-Simons theory

In this work, we examine a family of $pp$-wave solutions of Minimal Massive 3d Gravity (MMG) minimally coupled with the Maxwell-Chern-Simons theory. An elaborate investigation of the field equations shows that the theory admits $pp$-wave solutions provided that there exist an anti-self duality relation between the electric and the magnetic components of the Maxwell 2-form field. By employing Noether-Wald formalism, we also construct Noether charges of the theory within exterior algebra formalism.

A note on inflation in dRGT massive gravity

Although the dRGT massive gravity successfully explains the late-time cosmic acceleration, it cannot justify inflation. On the other hand, and in the frameworks of General Relativity and modified gravity, the interests and attempts to describe dark energy and inflation by using Lagranginas, which may have pole, have recently been enhanced. Subsequently, we are going to show that this kind of Lagrangian may justify inflation in the framework of dRGT massive gravity. The study is done focusing on the power and exponential potentials, and the results show a plausible consistency with the Planck 2…

Note on black hole no hair theorems for massive forms and spin-1/2 fields

We give a proof of the non-perturbative no hair theorems for a massive 2-form field with 3-form field strength for general stationary axisymmetric and static (anti)-de Sitter or asymptotically flat black hole spacetimes with some suitable geometrical properties. The generalization of this result for higher form fields is discussed. Next, we discuss the perturbative no hair theorems for massive spin-1/2 fields for general static backgrounds with electric or magnetic charge. Some generalization of this result for stationary axisymmetric spacetimes are also discussed. All calculations are done in…

A note on the uniqueness of the dRGT massive gravity theory

We revisit the problem of gravity coupled to a background metric $η_{μν}$, looking for ghost free interactions. It is known that elimination of the Boulware-Desewr ghost is equivalent to a certain Hessian condition on the interacting potential. We elaborate on this equation and provide a proof that dRGT potential is the unique interaction between the spacetime metric and a background field $η_{μν}$ which is both Lorentz invariant and ghost free. Our approach is fully non-perturbative using only the ADM formulation of general relativity.

A Note on Coherent States with Quantum Gravity Effects

Existence of a minimal measurable length and an upper bound for the momentum fluctuations are the casting reasons for generalization of uncertainty principle and then reformulation of Hilbert space representation of quantum mechanics. In this paper, we study the consequences of the Generalized Uncertainty Principle (GUP) in the presence of both minimal length and maximal momentum. We consider a simple harmonic oscillator in the framework of GUP by introducing it's energy eigenstates and energy spectrum. Investigation of coherent states for a generalized harmonic oscillator and it's generic beh…

Gravitational Waves Notes, Issue #3 : "Stellar cusps in galactic nuclei - How stars distribute around a massive black hole"

GW Notes was born from the need for a journal where the distinct communities involved in gravitation wave research might gather. While these three communities - Astrophysics, General Relativity and Data Analysis - have made significant collaborative progress over recent years, we believe that it is indispensable to future advancement that they draw closer, and that they speak a common idiom. For this GW Notes issue we have approached Miguel Preto (Heidelberg University) to expand a recent work on how stars distribute around massive black holes for our highlight article.

Linear Degeneracy of the First-Order Generalized-Harmonic Einstein System

The purpose of this note is to clarify the conditions under which the first-order generalize-harmonic representation of the vacuum Einstein evolution system is linearly degenerate.

Gravitational Waves Notes, Issue #5 : "The Capra research programme for capture of small compact objects by massive black holes"

GW Notes was born from the need for a journal where the distinct communities involved in gravitation wave research might gather. While these three communities - astrophysics, general relativity and data analysis - have made significant collaborative progress over recent years, we believe that it is indispensable to future advancement that they draw closer, and that they speak a common idiom. In this 6th GW Note (since we started numbering with #0), we present the work of Jonathan Thornburg, who has been fully-refereed, on the Capra research programme for capture of small compact objects by mas…

Note on the effect of a massive accretion disk in the measurements of black hole spins

The spin measurement of black holes has important implications in physics and astrophysics. Regardless of the specific technique to estimate the black hole spin, all the current approaches assume that the space-time geometry around the compact object is exactly described by the Kerr solution. This is clearly an approximation, because the Kerr metric is a stationary solution of the vacuum Einstein equations. In this paper, we estimate the effect of a massive accretion disk in the measurement of the black hole spin with a simple analytical model. For typical accretion disks, the mass of the disk…

关于脉冲星定时阵列相关函数由 peculiar velocities 引起的注记

Note on pulsar timing array correlation functions induced by peculiar velocities

本文通过谐波空间计算验证了脉冲星定时阵列重叠减少函数受 peculiar velocities 影响的结果，并展示了其在spin-1引力波和天体测量学相关性中的应用。