Limits on the Anomalous Speed of Gravitational Waves From Binary Pulsars

Hermano Velten,Federico Piazza,Jose Beltrán Jiménez

doi:10.1142/s2010194517600163

Abstract

A large class of modified theories of gravity used as models for dark energy predict a propagation speed for gravitational waves which can differ from the speed of light. This difference of propagations speeds for photons and gravitons has an impact in the emission of gravitational waves by binary systems. Thus, we revisit the usual quadrupolar emission of binary system for an arbitrary propagation speed of gravitational waves and obtain the corresponding period decay formula. We then use timing data from the Hulse-Taylor binary pulsar and obtain that the speed of gravitational waves can only differ from the speed of light at the percentage level. This bound places tight constraints on dark energy models featuring an anomalous propagations speed for the gravitational waves.

Highlights

The direct detection of gravitational waves by the Laser Interferometer Gravitational-Wave Observatory (LIGO) has inaugurated the era of Gravitational Waves (GWs) astronomy.[1]
A large class of modified theories of gravity used as models for dark energy predict a propagation speed for gravitational waves which can differ from the speed of light
We have obtained the constraints imposed by the Hulse-Pulsar binary system measurements on a modification of the radiative sector of gravity

Summary

Introduction

The direct detection of gravitational waves by the Laser Interferometer Gravitational-Wave Observatory (LIGO) has inaugurated the era of Gravitational Waves (GWs) astronomy.[1] This breakthrough in the observation of the universe This is an Open Access article published by World Scientific Publishing Company. We need dark matter in order to explain, e.g., weak lensing and structures formation Another major discovery in modern cosmology is the late-time accelerating expansion of the universe, what is broadly called dark energy. In both cases, efforts have been made to explain the observations without additional components, but by modifying the gravitational interaction on the appropriate scales. It is very important to notice that, for a large class of theories, our bounds will apply even to models featuring screening mechanismsa la Vainshtein because the anomalous GW speed persists even inside screened environments.[3]

Modifying the Radiative Sector of Gravitational Theories

Binary Pulsar Constraints

Discussion