Conveners
Gravitational Waves and Scalar perturbations
- Luca Di Luzio (INFN Padova)
Long-lived heavy particles present during the big bang could have a decay channel opened by gravitons. Such decays can produce gravitational waves with large enough abundance to be detectable, and a peculiar narrow spectrum peaked today around optical frequencies. We identify which particles can decay in one or two gravitons. The maximal gravitational wave abundance arises from theories with...
High-frequency gravitational waves (HFGWs) provide a unique probe into early Universe physics and exotic astrophysical objects. While current and future gravitational wave detectors work on lower frequencies, graviton-to-photon conversion in strong magnetic fields offers a complementary detection method suitable for HFGW. Neutron stars, with their extreme magnetic fields ($\sim 10^{13}$...
We discuss the scalar-induced-gravitational-wave (SIGW) signal from primordial black hole (PBH) evaporation. In the monochromatic scenario, a significant signal is generated by the poltergeist mechanism as a result of a sudden transition from matter to radiation dominance. Non-trivial mass distributions affect this mechanism by prolonging the transition period. We show that for realistic mass...
Recently, several papers have claimed that superhorizon curvature perturbations are not conserved at the one-loop level in single-field inflation models if there is a transient ultra-slow-roll period. In this talk, I point out that the contributions from the counterterms were overlooked in the recent papers. I show that the counterterm contributions play a crucial role in canceling the...
In this talk, we investigate the spectral behavior of scalar fluctuations generated by gravity during inflation and reheating, employing a non-perturbative Bogoliubov treatment within the framework of gravitational reheating. We obtain both long and short-wavelength spectra. It highlights that the spectral index in the IR regime varies depending on the post-inflationary equation of state (EoS)...
