Neutrinos Besson, Dave; Cowen, Doug; Selen, Mats ...
Proceedings of the National Academy of Sciences - PNAS,
12/1999, Volume:
96, Issue:
25
Journal Article
Peer reviewed
Open access
Neutrinos represent a new "window" to the Universe, spanning a large range of energy. We discuss the science of neutrino astrophysics and focus on two energy regimes. At "lower" energies (≈ 1 MeV), ...studies of neutrinos born inside the sun, or produced in interactions of cosmic rays with the atmosphere, have allowed the first incontrovertible evidence that neutrinos have mass. At energies typically one thousand to one million times higher, sources further than the sun (both within the Milky Way and beyond) are expected to produce a flux of particles that can be detected only through neutrinos.
In the standard picture of galactic cosmic rays, a diffuse flux of high-energy gamma-rays and neutrinos is produced from inelastic collisions of cosmic ray nuclei with the interstellar gas. The ...neutrino flux is a guaranteed signal for high-energy neutrino observatories such as IceCube, but has not been found yet. Experimental searches for this flux constitute an important test of the standard picture of galactic cosmic rays. Both the observation and non-observation would allow important implications for the physics of cosmic ray acceleration and transport. We present CRINGE, a new model of galactic diffuse high-energy gamma-rays and neutrinos, fitted to recent cosmic ray data from AMS-02, DAMPE, IceTop as well as KASCADE. We quantify the uncertainties for the predicted emission from the cosmic ray model, but also from the choice of source distribution, gas maps and cross-sections. We consider the possibility of a contribution from unresolved sources. Our model predictions exhibit significant deviations from older models. Our fiducial model is available at https://doi.org/10.5281/zenodo.7373010 .
In this contribution the current observational results for the diffuse flux of high-energy astrophysical neutrinos are reviewed. In order to understand the science implications, the measurements in ...different detection channels are discussed and results are compared. The discussion focuses is the energy spectrum, the flavor ratio and large scale anisotropy.
NuCraft (nucraft.hepforge.org) is an open-source Python project that calculates neutrino oscillation probabilities for neutrinos from cosmic-ray interactions in the atmosphere for their propagation ...through Earth. The solution is obtained by numerically solving the Schr\"odinger equation. The code supports arbitrary numbers of neutrino flavors including additional sterile neutrinos, CP violation, arbitrary mass hierarchies, matter effects with a configurable Earth model, and takes into account the production height distribution of neutrinos in the Earth's atmosphere.
In this work we investigate and parameterize the amount and angular distribution of Cherenkov photons which are generated by electromagnetic cascades in water or ice. We simulate electromagnetic ...cascades with Geant4 for primary electrons, positrons and photons with energies ranging from 1 GeV to 10 TeV. We parameterize the total Cherenkov light yield as a function of energy, the longitudinal evolution of the Cherenkov emission along the cascade-axis and the angular distribution of photons. Furthermore, we investigate the fluctuations of the total light yield, the fluctuations in azimuth and changes of the emission with increasing age of the cascade.
The IceCube Neutrino Observatory has discovered a diffuse all-flavor flux of high-energy astrophysical neutrinos. However, the corresponding astrophysical sources have not yet been identified. ...Neither significant point sources nor significant angular correlations of event directions have been observed by IceCube or other instruments to date. We present a new method to interpret the non-observation of angular correlations in terms of exclusions on the strength and number of point-like sources in generic astrophysical scenarios. Additionally, we constrain the presence of these sources taking into account the measurement of the diffuse high-energy neutrino flux by IceCube. We apply the method to two types of astrophysically motivated source count distributions: The first type is obtained by considering the cosmological evolution of the co-moving density of active galaxies, while the second type is directly derived from the gamma ray source count distribution observed by Fermi-LAT. As a result, we constrain the possible parameter space for both types of source count distributions.
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