# Non-linear aspects and symmetries of black hole perturbation theory

The thesis will study theoretical aspects and symmetries of black hole perturbation theory, with applications to future gravitational-wave observations.

The discovery of astrophysical neutrino signal by IceCube neutrino telescope has extended the energy frontier of astronomy into Peta-electronvolt energy range. The nature of astronomical sources is currently uncertain. A breakthrough toward understanding of the nature of these sources can be achieved via detection of the gamma-ray counterpart of the astrophysical neutrino signal. Gamma-ray signal at 100 TeV is now detectable by the HAWC, Tibet and LHAASO telescopes. Further powerful observational facilities, like CTA and SWGO telescopes are under construction or planned.

Astronomical observations through the new 100 TeV gamma-ray observational window by HAWC, Tibet and LHAASO air shower arrays, and, in the near future, by the Cherenkov Telescope Array CTA open a range of completely new possibilities for the study of highest energy galactic cosmic ray sources. These sources, dubbed "PeVatrons" (yet to be identified) produce particles with energies in excess of Peta-electronVolt, three orders of magnitude higher than those attained in the most powerful human-made accelerator LHC.

Neutrinos are elementary massive particles with mixings. They change their flavor while propagating. The vacuum oscillations discovered in 1998 by the Super-Kamiokande Collaboration is a breakthrough, with an impact in particle physics, astrophysics and cosmology.

The aim of this thesis is the study of the quantum to classical transition

with a particular interest to quantum to classical gravity.

Of fundamental importance are the imprints left from quantum phenomenon

in the observed signal, such as CMB anisotropies and gravitational waves.

Quantum gravity is a hard task to tackle head-on.

Electromagnetism however is a case in which such a transition is well grounded this is the reason why,

as a starting point, we will consider the well known case of the electromagnetic field.

with a particular interest to quantum to classical gravity.

Of fundamental importance are the imprints left from quantum phenomenon

in the observed signal, such as CMB anisotropies and gravitational waves.

Quantum gravity is a hard task to tackle head-on.

Electromagnetism however is a case in which such a transition is well grounded this is the reason why,

as a starting point, we will consider the well known case of the electromagnetic field.

Study of the Quantum to classical transition (Directeur de these E.

Huguet APC UMR 7164, Univ. Paris Cité, co-encadrant J. Quéva, SPE UMR

6134, Univ. de Corse)

Quantum gravity is a hard task to tackle head-on.

Huguet APC UMR 7164, Univ. Paris Cité, co-encadrant J. Quéva, SPE UMR

6134, Univ. de Corse)

The aim of this thesis is the study of the quantum to classical transition

with a particular interest to quantum to classical gravity.

Of fundamental importance are the imprints left from quantum phenomenon

in the observed signal, such as CMB anisotropies and gravitational waves.

with a particular interest to quantum to classical gravity.

Of fundamental importance are the imprints left from quantum phenomenon

in the observed signal, such as CMB anisotropies and gravitational waves.

Quantum gravity is a hard task to tackle head-on.