Polarization Modes of Gravitational Wave for Viable f(R) Models

TL;DR

This paper investigates the polarization modes of gravitational waves in specific f(R) gravity models, revealing additional scalar modes beyond those predicted by general relativity, classified under E(2) symmetry.

Contribution

It identifies extra scalar polarization modes in certain f(R) models using Newman-Penrose formalism, expanding understanding of gravitational wave properties in modified gravity theories.

Findings

Two scalar polarization modes found in f(R) models

Gravitational waves classified as E(2) class II_{6}

Extra modes include longitudinal and transversal scalar modes

Abstract

In this paper, we study the gravitational wave polarization modes for some particular $f(R)$ models using Newman-Penrose formalism. We find two extra scalar modes of gravitational wave (longitudinal and transversal modes) in addition to two tensor modes of general relativity. We conclude that gravitational waves correspond to class $II_{6}$ under the Lorentz-invariant E(2) classification of plane null waves for these $f(R)$ models.