Fermion Soliton Black Holes

• Francesco Mattia Carone

We lack certainty about what truly lies inside black holes. Although observational evidence for their existence continues to grow, no robust theoretical framework has yet resolved the problem of the gravitational singularities that may be hidden within them. It is believed that singularities arise as an artifact of the breakdown of classical general relativity at Planckian scales. A pragmatic approach is thus to construct classical effective, singularity-free black hole spacetimes: regular black holes. This was the context of my thesis, which proved the non-existence of a particular class of non-rotating regular black holes: fermion soliton black holes

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Why do we care about Black Holes in cosmology?

• Grégoire Pierra

The LIGO-Virgo-KAGRA collaboration has just wrapped up its fourth observing run, collecting over 250 gravitational-wave candidates, most of them coming from pairs of black holes merging into each other. By looking at the overall properties of these black holes as a population, we can actually learn something about how fast the Universe is expanding, today and in the past. This idea, known as spectral sirens, isnt precise enough yet to compete with other ways of measuring the Hubble constant, one of the biggest tension in cosmology right now, but it is a completely independent method with a lot of potential. In this talk, I ll go over the basic idea and share the latest results from gravitational-wave cosmology.

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