This book, designed as a tool for young researchers and graduate students, reviews the main open problems and research lines in various fields of astroparticle physics: cosmic rays, gamma rays, neutrinos, cosmology, and gravitational physics. The opening section discusses cosmic rays of both galactic and extragalactic origin, examining experimental results, theoretical models, and possible future developments. The basics of gamma-ray astronomy are then described, including the detection methods and techniques. Galactic and extragalactic aspects of the field are addressed in the light of recent discoveries with space-borne and ground-based detectors. The review of neutrinos outlines the status of the investigations of neutrino radiation and brings together relevant formulae, estimations, and background information. Three complementary issues in cosmology are examined: observable predictions of inflation in the early universe, effects of dark energy/modified gravity in the large-scale structure of the universe, and neutrinos in cosmology and large-scale structures. The closing section on gravitational physics reviews issues relating to quantum gravity, atomic precision tests, space-based experiments, the strong field regime, gravitational waves, multi-messengers, and alternative theories of gravity.

This book, designed as a tool for young researchers and graduate students, reviews the main open problems and research lines in various fields of astroparticle physics: cosmic rays, gamma rays, neutrinos, cosmology, and gravitational physics. The opening section discusses cosmic rays of both galactic and extragalactic origin, examining experimental results, theoretical models, and possible future developments. The basics of gamma-ray astronomy are then described, including the detection methods and techniques. Galactic and extragalactic aspects of the field are addressed in the light of recent discoveries with space-borne and ground-based detectors. The review of neutrinos outlines the status of the investigations of neutrino radiation and brings together relevant formulae, estimations, and background information. Three complementary issues in cosmology are examined: observable predictions of inflation in the early universe, effects of dark energy/modified gravity in the large-scale structure of the universe, and neutrinos in cosmology and large-scale structures. The closing section on gravitational physics reviews issues relating to quantum gravity, atomic precision tests, space-based experiments, the strong field regime, gravitational waves, multi-messengers, and alternative theories of gravity.

This book covers the field of neutrino physics and astrophysics, providing an up-to-date presentation of the different research topics on the frontier of the field. It starts with a historical description to understand how the different aspects of our knowledge about the neutrinos evolved up to the present state. The main required elements of the Standard Model of electroweak interactions are introduced, and the different neutrino interactions and detection techniques are presented. We introduce the various ways to give neutrinos a mass and the phenomenon of neutrino oscillations which provides the main evidence for non-vanishing neutrino masses. We then consider the neutrinos produced in the Sun, what we have learned from them, and how they can also be useful to study our star. The geoneutrinos produced by the radioactivity in the Earth are discussed and the status of their detection is presented. We survey the neutrino production in the supernova explosions at the end of the life of very massive stars, what has been observed in SN1987A, and what could be learned from a future supernova or from the observation of the diffuse supernova neutrino background. We describe in detail the neutrino production by cosmic rays interacting in the atmosphere, the evidence for their flavor oscillations, and the oscillograms to describe their flavor change in terrestrial matter. The different mechanisms of production of high-energy astrophysical neutrinos and the observations achieved with the IceCube detector are presented, also discussing their flavor content by means of the flavor triangle. We then examine the cosmological neutrino background, its impact on Big Bang nucleosynthesis and on the CMB observations, with the associated bound on their masses and effective number. Finally, we review the basics of the leptogenesis scenarios, which provide an attractive explanation for the observed baryon asymmetry of the Universe.