Since the detection of the binary neutron star merger GW170817, gravitational waves (GWs) are rapidly entering in the field of cosmology. In this talk I will discuss how GWs can be used to probe deviations from General Relativity (GR) on cosmological scales. In particular I will focus on a modified GW friction term and a modified dispersion relation, while at the same time leaving the Hubble...
The direct detection of gravitational waves in 2015 offered a new probe of the structure of spacetime. The study of the propagation of the gravitational waves from the coalescence of binary systems of black holes detected by LIGO and Virgo already enabled to constrain the dispersive nature of gravitational waves. This talk presents the current work towards probing the birefringent nature of...
We compute gravitational mass and angular momentum multipole moments for four-dimensional black holes and fuzzball geometries thereof. For Kerr and for supersymmetric black holes many multipole moments vanish, but we show that an infinite number of ratios of vanishing multipoles are constant. We calculate these ratios for the first time, using two very different methods; the results agree...
Black-hole microstate (fuzzball) geometries are the only explicit top-down constructions of structure at the scale of the horizon, which is needed to solve the Information Paradox. We compute for the first time the Tidal Love Numbers of certain microstate geometries, and compare them to those of the corresponding black hole. We also discuss the implications for the physics of the structure at...
