Conveners
Astrophysics
- William Shepherd
We use multimessenger observations of the neutron star merger event GW170817 to derive the first merger constraints on axion-like particles (ALPs) coupling to photons. ALP production from Primakoff and photon coalescence processes is calculated; then, the region of parameter space where ALPs can escape the remnant and decay back into two photons is considered. This gives rise to an ALP-induced...
We initiate a study of the gravitational wave signatures of a phase transition that occurs as the Universe's temperature increases during reheating. The gravitational wave signatures of a heating phase transition are different from those of a cooling phase transition and observation of them would allow us to probe reheating. In the lucky case that the gravitational wave signatures from both...
In the last few years increased precision of experimental data led to challenges to ΛCDM. The dynamics of the expansion and the statistics of the growth of structure appear to be in tension between local measurements and inference from the CMB. I will discuss the H0 and S8 tensions and discuss new physics solutions in the context of dark matter/energy and quantum gravity.
