Gravitational waves induced by scalar perturbations during a gradual transition from an early matter era to the radiation era

By Keisuke Inomata, K. Kohri, T. Nakama, T. Terada. Journal of Physics, Conference Series, 2019

144 citations recorded by the source corpus.

We revisit the effects of an early matter-dominated era on gravitational waves induced by scalar perturbations. We carefully take into account the evolution of the gravitational potential, the source of these induced gravitational waves, during a gradual transition from an early matter-dominated era to the radiation-dominated era, where the transition timescale is comparable to the Hubble time at that time. Realizations of such a gradual transition include the standard perturbative reheating with a constant decay rate. Contrary to previous works, we find that the presence of an early matter-dominated era does not necessarily enhance the induced gravitational waves due to the decay of the gravitational potential around the transition from an early matter-dominated era to the radiation-dominated era.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/d935cb0a24817626bcd15ed2495f57bd2e152f03

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In Astronomy and Astrophysics

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Citations in the corpus

• Primordial black holes and gravitational waves from parametric amplification of curvature perturbations (2019, background): “On the other hand, those large curvature perturbations, as source of the tensor perturbations, would result in an isotropic stochastic gravitational wave (GW) background observable today [23–43].”
• Challenges and opportunities of gravitational-wave searches at MHz to GHz frequencies (2020, background): “(Second order GWs are also produced in an early matter era, Inomata et al. 2019a, b.) The amplitude of this signal is quadratic in the scalar perturbations, and scale-invariant O 10 5 perturbations, as measured on large scales by the CMB, result in unobservable GWs due to too small amplitude.”
• Gravitational waves from a universe filled with primordial black holes (2020, background): “Although an accurate assessment of the signal would require to properly resolve the dynamics of the induced gravitational waves during the gradual transition between the PBH-dominated and the radiation-dominated era [64], let us note that since we have found that the energy spectrum peaks at the Hub”