Graviton Mass in the Era of Multi-Messenger Astronomy

Aleksandra Piórkowska-Kurpas

doi:10.3390/universe8020083

Abstract

The idea of massive graviton plays a fundamental role in modern physics as a landmark of most scenarios related to modified gravity theories. Limits on graviton mass can be obtained through different methods, using all the capabilities of multi-messenger astronomy available today. In this paper, we consider some emerging opportunities. In particular, modified relativistic dispersion relations of massive gravitons may lead to changes in the travel time of gravitational waves (GWs) emitted from distant astrophysical objects. Strong gravitational lensing of signals from a carefully selected class of extra-galactic sources such as compact object binaries (actually, binary neutron stars) is predicted to play an important role in this context. Comparing time delays between images of the lensed GW signal and its electromagnetic (EM) counterpart may be a new model-independent strategy (proposed by us in X.-L. Fan et al., 2017), which is especially promising in light of the fruitful observing runs of interferometric GW detectors, resulting in numerous GW signals. In addition to this direct, kinematic method, one can use an indirect, static method. In this approach, the non-zero graviton mass would modify estimates of the total cluster mass via a Yukawa term, influencing the Newtonian potential. In A. Piórkowska-Kurpas et al., 2022, using the X-COP galaxy cluster sample, we obtained mg<(4.99−6.79)×10−29 eV (at 95% C.L.), which is one of the best available constraints.

Highlights

If our understanding that all fundamental interactions, including gravity, really do have their quantum versions is correct, the carrier of gravity—a massless particle of spin 2—should exist
Would be able to detect 50–100 lensed gravitational waves (GWs) events per year; DECihertz Interferometer Gravitational wave Observatory (DECIGO)/B-DECIGO could register about 50 lensed GW events each year
These would be mainly binary black hole systems, especially in the DECIGO/B-DECIGO case, in which the contamination of unresolved double compact object systems dramatically lowers the ability for the detection of the lensed binary neutron star or mixed, neutron star-black hole coalescences

Summary

Introduction

If our understanding that all fundamental interactions, including gravity, really do have their quantum versions is correct, the carrier of gravity—a massless particle of spin 2 (the graviton)—should exist. Experimental confirmation of the graviton has not yet taken place (this is a highly difficult task), which opens up room for discussion concerning the real nature of the phenomenon of gravity In this light, the idea of a massive graviton may play a fundamental role as a landmark of most scenarios related to the modification (or replacement) of general relativity as a theory of gravity. Due to the lack of conclusive data allowing one to uncover the true nature of the dark energy phenomenon, it is reasonable to describe it phenomenologically as a cosmological constant within the standard cosmological model for a flat Universe, with cold dark matter being taken into account [1,2,3,4,6] This so-called ΛCDM scenario shows strong agreement with observational data and seems to be the simplest and the most useful one, incorporating dark energy and dark matter phenomena within a single framework. The most recent upper limit on the graviton’s mass obtained using this method with the data for the X-COP cluster sample is shown

Time Delay Technique in Probing Graviton Mass

Constraints on Graviton Mass with GW Signals

Gravitational Lensing of GWs for Graviton Mass Estimates

Graviton Mass from Dynamical Properties of Galaxy Clusters

Summary and Discussion of Perspectives