Paolo Pani – författare

This book focuses on one mechanism in black hole physics which has proven to be universal, multifaceted and with a rich phenomenology: rotational superradiance. This is an energy extraction process, whereby black holes can deposit their rotational energy in their surroundings, leading to Penrose processes, black-hole bombs, and even Hawking radiation. Black holes are key players in star formation mechanisms and as engines to some of the most violent events in our universe. Their simplicity and compactness make them perfect laboratories, ideally suited to probe new fields or modifications to the theory of gravity. Thus, black holes can also be used to probe some of the most important open problems in physics, including the nature of dark matter or the strong CP problem in particle physics.

This second edition stresses the role of ergoregions in superradiance, and completes its catalogue of energy-extraction processes. It presents a unified description of instabilities of spinning black holes in the presence of massive fields. Finally, it covers the first experimental observation of superradiance, and reviews the state-of-the-art in the searches for new light fields in the universe using superradiance as a mechanism.

This volume gives a unified picture of the multifaceted subject of superradiance, with a focus on recent developments in the field, ranging from fundamental physics to astrophysics.

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 mechanics and especially in relativity and astrophysics. In Einstein''s General Relativity, black-hole superradiance is permitted by dissipation at the event horizon, which allows energy extraction from the vacuum, even at the classical level. When confined, this amplified radiation can give rise to strong instabilities known as "blackhole bombs'''', which have applications in searches for dark matter, in physics beyond the Standard Model and in analog models of gravity. This book discusses and draws together all these fascinating aspects of superradiance.

Primordial black holes (PBHs) were proposed more than 50 years ago as black holes possibly formed across a vast mass range in the early universe. They represent a unique probe to access the primordial universe and cosmological inflation. Furthermore, in certain mass ranges, they could comprise the entirety of the dark matter, seed supermassive black holes at high redshift, be responsible for some gravitational-wave events detected so far, and be novel gravitational-wave sources detectable with future instruments. However, detecting PBHs has proved to be extremely challenging and extensive research focused on setting a variety of constraints on the fraction of dark matter composed by these objects.

This book highlights an up-to-date, comprehensive overview on this subject, including pedagogical details on the PBH formation scenarios, cosmological evolution, astrophysical implications, connections with gravitational-wave astronomy, and critical discussion of the latest and future constraints.

At variance with all existing reviews on this subject, this book addresses graduate students and researchers not necessarily familiar with all areas of the topic, providing details on important key results rather than collecting and reviewing the latest literature.

The topic is naturally interdisciplinary and connects areas as diverse as cosmology, particle physics, gravitational-wave astronomy, and numerical simulations. To reflect this diversity, the book includes 25 contributions from key researchers working in these different areas. It provides a unique reference both to approach the topic for the first time and to learn a specific specialized sub-area.