Quasinormal modes of modified gravity (MOG) black holes

Luciano Manfredi,Jonas Mureika,John Moffat

doi:10.1016/j.physletb.2017.11.006

Luciano Manfredi, Jonas Mureika + Show 1 more

Open Access

https://doi.org/10.1016/j.physletb.2017.11.006

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Abstract

The Quasinormal modes (QNMs) for gravitational and electromagnetic perturbations are calculated in a Scalar–Tensor–Vector (Modified Gravity) spacetime, which was initially proposed to obtain correct dynamics of galaxies and galaxy clusters without the need for dark matter. It is found that for the increasing model parameter α, both the real and imaginary parts of the QNMs decrease compared to those for a standard Schwarzschild black hole. On the other hand, when taking into account the 1/(1+α) mass re-scaling factor present in MOG, Im(ω) matches almost identically that of GR, while Re(ω) is higher. These results can be identified in the ringdown phase of massive compact object mergers, and are thus timely in light of the recent gravitational wave detections by LIGO.

Highlights

We are at the dawn of the era of gravitational wave astronomy
The ringdown phase – in which the final black hole horizon “settles” down through damped oscillations – is in turn characterized by quasinormal mode vibrations (QNMs) [11]
We begin by reviewing the essentials of Modified Gravity (MOG), QNMs, and the Asymptotic Iteration Method (AIM), after which we present the = 2, 3, 4 frequencies of gravitational and = 1, 2, 3 electromagnetic perturbations

Summary

Introduction

We are at the dawn of the era of gravitational wave astronomy. The four binary black hole merger signals observed by LIGO since September 2015 – GW150914 [1], GW-151226 [2], GW-170104 [3] and GW170814 [4] – serve as concrete evidence of the existence of black holes, but allow us to explore classical (and potentially quantum) gravitational physics in a new fashion. Gravitational waves present a novel test of the underlying theory of gravitation, since their characteristics depend uniquely on the background spacetime structure Such data can be a testbed for general relativity (GR) [6], as well as all alternate theories of gravitation [7, 8, 9, 10]. We discuss the distinctions between MOG QNMs and GR QNMs, and consider the experimental detection of QNMs in either LIGO or LISA data, and the possibility of distinguihing GR from MOG QNMs. In the following, we will investigate the ringdown phase of merging black holes producing gravitational waves in the generalized theory of gravitational STVG (MOG) [20].

MOG Black Holes

Calculating Quasinormal Modes

The Asymptotic Iteration Method

Quasinormal Modes of Static MOG Black Holes

Conclusions