Cosmic Rays
Describe (in order of magnitude) the average deflections that charged particles experience in the Galactic magnetic field as a function of Z & E
deflection parameter ~ 10 degrees * Z (E / 10 EeV)^-1
Order of magnitude of cross section for astrophysical neutrinos
around 1e-34 cm^2
how do IACTs detect gamma rays?
through the Cherenkov radiation observed at each telescope, combine them and compare image with MC-simulated gamma-ray air shower
List all second-generation GW detectors
LIGO, VIRGO, KAGRA
How does Xmax depend on zenith angle?
Larger zenith angle => more atmospheric depth => lower Xmax
At which energies do astrophysical neutrinos reside?
from 1e3 to 1e7 GeV
1e-12 m onwards (no lower limit)
explain how a gravitational wave is measured through interferometry
observe the interference pattern from two lasers at very large distances, the optical path will be shifted from the amplitude of the GW that locally changes space-time
Why havent we found UHECR sources yet, despite having over 50 events > 100 EeV?
their distribution is isotropic and do not pinpoint to any source (e.g. Amaterasu shows that it comes from the local void)
How can we measure neutrino oscillations?
an example: induce an interaction far away that we know the neutrino flavour of. Then in a far away detector, observe the appearance / disappearance of flavours
How is the direction reconstruction for gamma rays typically performed?
using a point-spread function (triple Gaussian or Kings function) to compare the true and reconstructed direction
describe the motivation of building the Einstein telescope
to test the limits of general relativity in strong field conditions, current GW detectors dont have the sensitivity to do so
Apart from deflections, what propagation effect affects our ability to detect UHECR sources? Explain the main mechanism related to this propagation effect.
Due to photo-nuclear disintegration. The Giant Dipole Resonance occurs due to interaction of nuclei with CMB / EBL photons, producing lighter nuclei in this process. This happens throughout -> mass composition changes throughout propagation
Explain the see-saw mechanism in the context of neutrino oscillations
possible explanation of the origin of neutrino mass, that the RH counterpart of neutrinos which are very heavy (& interact with the Higgs field) and induces small amount of mass to the LH neutrino
Explain how pulsar wind nebulae produce gamma rays
rotating magnetic field around pulsar accelerate charged particles -> production of e+e- pairs -> gamma rays produced at wind acceleration region
describe the observable objects in each regime of the GW frequency spectrum (1e-10 - 1e-6, 1e-4 - 1e0, 1e0 - 1e4) and examples of detectors that can be used to detect it
1e-10 - 1e-6 : stochastic background, PTA
1e-4 - 1e0 : massive binaries / inspirals, LISA
1e0 - 1e4 : compact binaries / core collapse SN, LIGO/VIRGO