Analytical expression for a class of spherically symmetric solutions in Lorentz breaking massive gravity

Abstract

We present a detailed study of the spherically symmetric solutions in Lorentz breaking massive gravity. There is an undetermined function $\mathcal{F}(X, w_1, w_2, w_3)$ in the action of St\"{u}ckelberg fields $S_{\phi}=\Lambda^4\int{d^4x\sqrt{-g}\mathcal{F}}$, which should be resolved through physical means. In the general relativity, the spherically symmetric solution to the Einstein equation is a benchmark and its massive deformation also play a crucial role in Lorentz breaking massive gravity. $\mathcal{F}$ will satisfy the constraint equation $T_0^1=0$ from the spherically symmetric Einstein tensor $G_0^1=0$, if we maintain that any reasonable physical theory should possess the spherically symmetric solutions. The St\"{u}ckelberg field $\phi^i$ is taken as a 'hedgehog' configuration $\phi^i=\phi(r)x^i/r$, whose stability is guaranteed by the topological one. Under this ans\"{a}tz, $T_0^1=0$ is reduced to $d\mathcal{F}=0$. The functions $\mathcal{F}$ for $d\mathcal{F}=0$ form a commutative ring $R^{\mathcal{F}}$. We obtain a general expression of solution to the functional differential equation with spherically symmetry if $\mathcal{F}\in R^{\mathcal{F}}$. If $\mathcal{F}\in R^{\mathcal{F}}$ and $\partial\mathcal{F}/\partial X=0$, the functions $\mathcal{F}$ form a subring $S^{\mathcal{F}}\subset R^{\mathcal{F}}$. We show that the metric is Schwarzschild, AdS or dS if $\mathcal{F}\in S^{\mathcal{F}}$. When $\mathcal{F}\in R^{\mathcal{F}}$ but $\mathcal{F}\notin S^{\mathcal{F}}$, we will obtain some new metric solutions. Using the general formula and the basic property of function ring $R^{\mathcal{F}}$, we give some analytical examples and their phenomenological applications. Furthermore, we also discuss the stability of gravitational field by the analysis of Komar integral and the results of QNMs.