Gravitational theories differing from General Relativity may explain the accelerated expansion of the Universe without a cosmological constant. However, their viability crucially depends on a “screening mechanism” needed to suppress, on small scales, the fifth force driving the cosmological acceleration. I will discuss a scalar-tensor theory with first-order derivative self-interactions...
I will present extreme mass ratio inspirals (EMRIs), during which a small body spirals into a supermassive black hole, in gravity theories with additional scalar fields. No-hair theorems and properties of known theories that manage to circumvent them introduce a drastic simplification to the problem: the effects of the scalar on supermassive black holes, if any, are mostly negligible for EMRIs...
In this talk I present three recent works [1,2,3] that aim to enhance our understanding of reconstructing black hole space-times from different type of observations. While gravitational wave detectors like LIGO/Virgo allow to perform black hole spectroscopy of stellar mass black holes, images such as those produced by the Event Horizon Telescope provide information of the shadow from super...
Gravitational waves from the coalescence of compact binaries provide a unique opportunity to test gravity in strong field regime. In particular, the postmerger phase of the gravitational signal is a proxy for the nature of the remnant.
This is of particular interest in view of some quantum-gravity models which predict the existence of horizonless compact objects that overcome the paradoxes...
In gravity theories that exhibit spontaneous scalarization, astrophysical objects are identical to their general relativistic counterpart until they reach a certain threshold in compactness or curvature. Beyond this threshold, they acquire a non-trivial scalar configuration, which also affects their structure. The onset of scalarization is controlled only by terms that contribute to linear...
Effective field theories (EFTs) facilitate what might otherwise be completely untenable calculations by helping us focus on only the most relevant physics at hand. Applied to general relativity, these techniques have famously improved our handle on post-Newtonian theory over the last decade, and extensions of these ideas are now also being developed to study how binary systems evolve when they...
