Abstract The Laser Interferometer Space Antenna (LISA) has the potential to reveal wonders
about the fundamental theory of nature at play in the extreme gravity regime, where the …

Very compact objects probe extreme gravitational fields and may be the key to understand
outstanding puzzles in fundamental physics. These include the nature of dark matter, the …

The dark photon is a massive hypothetical particle that interacts with the Standard Model by
kinetically mixing with the visible photon. For small values of the mixing parameter, dark …

The dawn of the twenty-first century came with very positive prospects for gravity, cosmology,
and astrophysics. Technological progress made it possible for cosmology to enter to its …

70 AIM, UMR 7158, CEA/DRF, CNRS, Université Paris Diderot, Irfu/Service d'Astrophysique,
Centre de Saclay, FR-91191 Gif-sur-Yvette, France

For ultra compact objects, light rings and fundamental photon orbits (FPOs) play a pivotal
role in the theoretical analysis of strong gravitational lensing effects, and of BH shadows in …

Ultracompact objects with light rings (LRs) but without an event horizon could mimic black
holes (BHs) in their strong gravity phenomenology. But are such objects dynamically viable …

In this article, I introduce ideas and techniques to extract information about the equation of
state of matter at very high densities from gravitational waves emitted before, during and …

Can a dynamically robust bosonic star (BS) produce an (effective) shadow that mimics that
of a black hole (BH)? We focus on models of spherical BSs with free scalar or vector fields …

In this work, we obtain the shadow images of spherically symmetric scalar boson and Proca
stars using analytical fittings of numerical solutions, when illuminated by a geometrically thin …