The exploration of the universe has recently entered a new era thanks to the multi-
messenger paradigm, characterized by a continuous increase in the quantity and quality of …

Clouds of ultralight bosons—such as axions—can form around a rapidly spinning black
hole, if the black hole radius is comparable to the bosons' wavelength. The cloud rapidly …

Ultralight bosons can form clouds around rotating black holes if their Compton wavelength is
comparable to the black hole size. The boson cloud spins down the black hole through a …

Superradiant instabilities may create clouds of ultralight bosons around rotating black holes,
forming so-called “gravitational atoms “. It was recently shown that the presence of a binary …

Black-hole superradiance has been used to place very strong bounds on a variety of models
of ultralight bosons such as axions, new light scalars, and dark photons. It is common lore to …

Superradiance is a radiation enhancement process that involves dissipative systems. With a
60 year-old history, superradiance has played a prominent role in optics, quantum …

Ultralight bosons are a class of hypothetical particles that could potentially solve critical
problems in fields ranging from cosmology to astrophysics and fundamental physics. If …

A plethora of theoretical arguments and experimental observations suggest evidence for
new physics beyond the standard model and general relativity. A promising way to detect …

The theory of quantum gravity (QG) still eludes us. To start with, it is not even clear if gravity
can be quantized like the rest of the fundamental interactions in Nature. For instance, gravity …

Abstract The Standard Model successfully codifies the fundamental particles and
interactions that are amenable to observation. Together with the general theory of relativity …