On Thursday 25th, we have the pleasure to host the Belgian Gravitational Waves meeting. It starts at 2pm, seminar room E349. Our guest speakers are Stefan Antusch and Giulia Cusin.
At 14:00, Stefan Antusch (Basel U.), will be talking about
Oscillons and gravitational waves from preheating after inflation
We discuss the preheating phase after inflation in particle physics motivated models of the early universe. We show that the non-linear dynamics after hilltop-type inflation models, where inflation can be linked to a particle physics phase transition, can lead to the formation of oscillons, comparatively long-lived and strong local fluctuations of the inflaton field. Similar types of scalar field potentials also appear in the KKLT scenario in string phenomenology, and oscillons can form for the modulus field. We argue that when the oscillons are asymmetric for a sufficiently long period, they can generate a peak in the otherwise rather broad gravitational wave spectrum produced during the earlier phases of preheating.
After a coffee break, at 15:30, Giulia Cusin (Oxford U.) will talk about
Astrophysical background of gravitational waves: from cosmology to a new era of precision astrophysics
The astrophysical background of gravitational waves (AGWB) is made up by the incoherent superposition of gravitational wave signals emitted by a large number of resolved and unresolved astrophysical sources from the onset of stellar activity until today, and that we collect at our detectors. I present a theoretical framework to fully characterize the AGWB in terms of energy density anisotropies and polarization and I show the first numerical predictions for the angular power spectra of anisotropies in different frequency bands and for cross-correlations with electromagnetic observables such as weak leaning and galaxy number counts. l then illustrate and discuss the astrophysical implications of this study. By properly modelling the properties of the AGWB, it will be possible to extract for the first time precise data on galactic and stellar physics and on astrophysical processes of GW emission. In the same way as the discovery and study of the cosmic microwave background has represented a turning point for cosmology, the study of the AGWB will represent a true revolution for astrophysics eventually leading to a new era of precision astrophysics.