Related papers: Unifying gravitational waves and dark energy
Motivated by some of the recent swampland conjectures, we study a model of dark energy, in which a quintessence axion slowly rolls in a steep potential due to its interactions with a U(1) or an SU(2) gauge field. The gauge fields produced…
The experimental possibility of detecting gravitational waves via their induced time perturbations is explored here, expanding from previous work. The oscillations of the time-time component in the metric are made explicit when working in…
Mixing between photons and low-mass bosons is well considered in the literature. The particular case of interest here is with hypothetical gravitons, as we are concerned with the direct conversion of gravitons into photons in the presence…
The response of a gravitational wave detector to scalar waves is analysed in the framework of the debate on the choice of conformal frames for scalar-tensor theories. A correction to the geodesic equation arising in the Einstein conformal…
Luminosity distance estimates from electromagnetic and gravitational wave sources are generally different in models of dynamical dark energy and gravity beyond the standard cosmological scenario. We show that this leaves a unique imprint on…
Metric perturbations in General Relativity are usually separated into three distinct classes: scalar, vector, and tensor. In many cases these modes are separable, i.e. they satisfy independent equations of motion for each mode. However, in…
In anticipation of upcoming gravitational wave experiments, we provide a comprehensive overview of the spectra predicted by phase transitions triggered by states from a large variety of dark sector models. Such spectra are functions of the…
This paper presents a systematic treatment of the linear theory of scalar gravitational perturbations in the synchronous gauge and the conformal Newtonian (or longitudinal) gauge. It differs from others in the literature in that we give, in…
An additional scalar degree of freedom for a gravitational wave is often predicted in theories of gravity beyond general relativity and can be used for a model-agnostic test of gravity. In this letter, we report the direct search for the…
With focus on the cosmological evolution of linear perturbations of matter and geometry, we calculate the equivalent expressions to that of the Newtonian and Synchronous gauges within the framework of Unimodular Gravity, being these two…
We study the matter one-loop quantum corrections to the gravitational sector in a gravity theory coupled with a nonlocal scalar field. We find that non-renormalizable divergences disappear when the propagator of the scalar field approaches…
We investigate the evolution of cosmological scalar perturbations in the case that the background radiation is weakly coupled to a light scalar field $\phi$. The light scalar $\phi$ is a homogeneous background field with a large initial…
In general relativity, it has been shown that the effective gravitational stress-energy tensor for short-wavelength metric perturbations acts just like that for a radiation fluid, and thus, in particular, cannot provide any effects that…
In general, modified gravity theories are modifications or extensions of Einstein's general relativity. Some of them give rise to additional scalar degrees of freedom in Nature. If these scalar fields exist and are light enough, they should…
The LIGO/VIRGO collaboration has recently announced the detection of gravitational waves from a neutron star-neutron star merger (GW170817) and the simultaneous measurement of an optical counterpart (the gamma-ray burst GRB 170817A). The…
Theories of dark energy and modified gravity can be strongly constrained by astrophysical or cosmological observations, as illustrated by the recent observation of the gravitational wave event GW170817 and of its electromagnetic counterpart…
Scalar perturbations of Friedmann-Lemaitre cosmologies can be analyzed in a variety of ways using Einstein's field equations, the Ricci and Bianchi identities, or the conservation equations for the stress-energy tensor, and possibly…
Basic aspects of the background of gravitational waves and its mathematical characterization are reviewed. The spectral energy density parameter $\Omega(f)$, commonly used as a quantifier of the background, is derived for an ensemble of…
The breakdown of conformal symmetry in a conformally invariant scalar-tensor gravitational model is revisited in the cosmological context. Although the old scenario of conformal symmetry breaking in cosmology containing scalar field has…
The Universe is not just cold dark matter and dark energy, it also contains baryons, radiation and neutrinos. The presence of these components, beyond the pressure-less cold dark matter and the quasi-uniform dark energy ones, imply that the…