Lecture on Cosmic Rays and Gamma Ray Bursts
Astroparticle Physics revolves around phenomena that involve
(astro)physics under the most extreme conditions.
Black holes with masses a billion times greater than the mass
of the Sun, accelerate particles to velocities close to the speed
of light.
The produced high-energy particles may be detected on Earth and as
such provide us insight in the physical processes underlying these
cataclysmic events. This is the arena of Cosmic Ray physics.
The current understanding is that protons and electrons are the
primary particles that are accelerated by electromagnetic fields at
a cosmic accelerator site.
Candidates for the production of the most energetic cosmic rays are
Active Galactic Nuclei (AGN) and Gamma Ray Bursts (GRBs).
The current perception is that the majority of these objects have a
similar inner engine, in which infalling matter and the likely presence
of a strong magnetic field gives rise to relativistic shock wave acceleration
in two back to back jets.
One of the main objectives in cosmic ray studies is the detection of
extraterrestrial high-energy neutrinos.
Having no electrical charge and interacting only weakly with matter,
neutrinos are special astronomical messengers. Only they can carry
information from violent cosmological events at the edge of the Universe
directly towards the Earth.
Furthermore, since they are hardly hindered by intervening matter, they are
the only messengers that can provide information about the central cores of
the cosmic accelerators.
As such, this new field of research, called Neutrino Astronomy, is poised to
provide new discoveries now that large scale neutrino observatories like
IceCube at the South Pole have become operational.
The current situation may be compared with the advent of radio astronomy,
which has led to unexpected discoveries like pulsars and many new insights.
In this course we will focus on the identification of high-energy neutrinos from
transient phenomena, i.e. Gamma Ray Bursts and flares of Active Galactic Nuclei,
which are believed to be the most violent cosmic events.
This high-energy neutrino component in the emitted fluxes allows us to investigate
the nature of the progenitors and inner engines of these mysterious phenomena.