Related papers: Universal Gravitational Waves from Interacting and…
Probing the polarization of gravitational waves (GWs) would provide an evidence of graviton, indicating the quantization of gravity. Motivated by the next generation of gravitational wave detectors, we make an attempt to study the possible…
The low frequency part of the gravitational wave spectrum generated by local physics, such as a phase transition or parametric resonance, is largely fixed by causality, offering a clean window into the early Universe. In this work, this low…
We investigate the gravitational wave background induced by the first order scalar perturbations in the curvaton models. We consider the quadratic and axion-like curvaton potential which can generate the blue-tilted power spectrum of…
Gravitational wave (GW) signals arising from binary neutron star mergers offer new, sensitive probes to ultralight mediators. Here we analyze the GW signals in the GW170817 event detected by the LIGO/Virgo collaboration to impose…
The focus of this Chapter is on describing the prospective sources of the gravitational wave universe accessible to present and future observations, from kHz, to mHz down to nano-Hz frequencies. The multi-frequency gravitational wave…
Oscillons are long-lived nonlinear pseudo-solitonic configurations of scalar fields and many plausible inflationary scenarios predict an oscillon-dominated phase in the early universe. Many possible aspects of this phase remain unexplored,…
We study the propagation of cosmological gravitational wave (GW) backgrounds from the early radiation era until the present day in modified theories of gravity. Comparing to general relativity (GR), we study the effects that modified…
The oscillating pressure of the ultralight scalar dark matter (DM) can induce the oscillation of the local gravitational potential. Similar to the time-dependent frequency shift for the pulse signals of pulsars, the oscillation of the local…
We present an in depth discussion of the production of gravitational waves from an inflationary phase that could have occurred in the early universe, giving derivations for the resulting spectrum and energy density. We also consider the…
The emission of gravitational waves from a system of massive objects interacting on elliptical, hyperbolic and parabolic orbits is studied in the quadrupole approximation. Analytical expressions are then derived for the gravitational wave…
The cosmological dynamics of gravitational clustering satisfies an approximate invariance with respect to the cosmological parameters that is often used to simplify analytical computations. We describe how this approximate symmetry gives…
Gravitational wave (GW) backgrounds of cosmological origin are expected to be nearly isotropic, with small anisotropies resembling those of the cosmic microwave background. We analyse the case of a scalar-induced GW background and clarify…
Phase transitions in the early universe can readily create an observable stochastic gravitational wave background. We show that such a background necessarily contains anisotropies analogous to those of the cosmic microwave background (CMB)…
We study the cosmological propagation of gravitational waves (GWs) beyond general relativity (GR) across homogeneous and isotropic backgrounds. We consider scenarios in which GWs interact with an additional tensor field and use a…
Current bounds from the polarization of the CMB predict the scale-invariant gravitational wave (GW) background of inflation to be out of reach for upcoming GW interferometers. This prospect dramatically changes if the inflaton is a…
After inflation, a period of preheating may have produced a stochastic background of high frequency gravitational waves (GWs) that would persist until today. The nature of the inflaton's coupling to Standard Model or other fields is…
We investigate the generation of gravitational waves due to the gravitational instability of primordial density perturbations in an early matter-dominated era which could be detectable by experiments such as LIGO and LISA. We use…
The cosmological background of gravitational waves can be tuned by the higher-order corrections to the gravitational Lagrangian. In particular, it can be shown that assuming $R^{1+\epsilon}$, where $\epsilon$ indicates a generic (eventually…
It is widely believed that the standard model is a low energy effective theory which may have higher dimensional non-renormalizable operators. The existence of these new operators can lead to interesting dynamics for the evolution of the…
We propose a new strategy to probe non-tensorial polarizations in the stochastic gravitational-wave (GW) background. Averaging over polarization angles, we find that three-point correlations of the GW signal vanish for tensor and vector…