Gravitational Wave Dynamics in Modified Gravity Theories

Gravitational waves offer an unprecedented laboratory for probing the fundamental nature of gravity beyond Einstein’s theory. In modified gravity frameworks—such as f(R) extensions, scalar–tensor formulations and teleparallel models—the generation and propagation of waves acquire novel features. These include additional polarizations beyond the familiar “plus” and “cross” tensor modes, dispersion effects arising from non-zero masses of scalar fields, and characteristic phase shifts compared to the predictions of general relativity. Such deviations become most pronounced in the strong-field regime around compact binaries and in the long-distance propagation of signals across cosmological scales. Theoretical studies now link specific waveform signatures to underlying modifications of the gravitational action, enabling advanced interferometric observatories and pulsar timing arrays to place stringent bounds on extra degrees of freedom, test the existence of extra dimensions, and constrain the dynamics of dark energy.

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Gravitational Wave Dynamics in Modified Gravity Theories publication trend

The graph below shows the total number of articles in gravitational wave dynamics in modified gravity theories across all publications each year (not limited to Nature Index journals).

Technical terms

Polarisation modes: Independent vibration patterns of gravitational waves, including tensor (plus and cross), scalar breathing and longitudinal states.

f(R) gravity: A generalisation of Einstein–Hilbert action where the Lagrangian is an arbitrary function of the Ricci scalar R, introducing a scalar degree of freedom.

Teleparallel gravity: An alternative formulation of gravity using torsion instead of curvature, characterised by a torsion scalar T and boundary term B.

Weak-field limit: A linear approximation of gravitational field equations around flat spacetime, used to derive wave solutions and polarisation content.

Pulsar timing array: A network of millisecond pulsars whose pulse arrival times are monitored to detect low-frequency gravitational waves via correlated timing residuals.

References

1. Classification of gravitational waves in higher-dimensional space-time and possibility of observation. European Physical Journal C (2023).
2. Weak field limit and gravitational waves in f(T, B) teleparallel gravity. European Physical Journal C (2020).
3. A new f(R) gravity model and properties of gravitational waves in it. European Physical Journal C (2020).