Using the Earth as a neutrino converter, tau neutrino fluxes from astrophysical point sources can be detected by tau-lepton-induced extensive air showers (EASs). Both muon neutrino and tau neutrino induced upward-going EAS signals can be detected by terrestrial, sub-orbital and satellite-based instruments. The sensitivity of these neutrino telescopes can be evaluated with the nuSpaceSim package, which includes the nuPyProp simulation package. The nuPyProp package propagates neutrinos (νμ, ντ) through the Earth to produce the corresponding charged leptons (muons and tau-leptons). We use nuPyProp to quantify the uncertainties from Earth density models, tau depolarization effects and photo-nuclear electromagnetic energy loss models in the charged lepton exit probabilities and their spectra. The largest uncertainties come from electromagnetic energy loss modeling, with as much as a 20-50% difference between the models. We compare nuPyProp results with other simulation package results.

Using the Earth as a neutrino converter, tau neutrino fluxes from astrophysical point sources can be detected by tau-lepton-induced extensive air showers (EASs). Both muon neutrino and tau neutrino induced upward-going EAS signals can be detected by terrestrial, sub-orbital and satellite-based instruments. The sensitivity of these neutrino telescopes can be evaluated with the nuSpaceSim package, which includes the nuPyProp simulation package. The nuPyProp package propagates neutrinos ($\nu_\mu$, $\nu_\tau$) through the Earth to produce the corresponding charged leptons (muons and tau-leptons). We use nuPyProp to quantify the uncertainties from Earth density models, tau depolarization effects and photo-nuclear electromagnetic energy loss models in the charged lepton exit probabilities and their spectra. The largest uncertainties come from electromagnetic energy loss modeling, with as much as a 20-50% difference between the models. We compare nuPyProp results with other simulation package results.

Ultra-high-energy neutrinos serve as messengers of some of the highest energy astrophysical environments. Given that neutrinos are neutral and only interact via weak interactions, neutrinos can emerge from sources, traverse astronomical distances, and point back to their origins. Their weak interactions require large target volumes for neutrino detection. Using the Earth as a neutrino converter, terrestrial, sub-orbital, and satellite-based instruments are able to detect signals of neutrino-induced extensive air showers. In this paper, we describe the software code nuPyProp that simulates tau neutrino and muon neutrino interactions in the Earth and predicts the spectrum of the τ-leptons and muons that emerge. The nuPyProp outputs are lookup tables of charged lepton exit probabilities and energies that can be used directly or as inputs to the nuSpaceSim code designed to simulate optical and radio signals from extensive air showers induced by the emerging charged leptons. We describe the inputs to the code, demonstrate its flexibility and show selected results for τ -lepton and muon exit probabilities and energy distributions. The nuPyProp code is open source, available on github.

The neutrino interaction length scales with energy, and becomes comparable to Earth's diameter above 10's of TeV energies. Over terrestrial distances, the tau's short lifetime leads to an energetic regenerated tau neutrino flux, tau neutrino to tau to tau neutrino, within the Earth. The next generation of neutrino experiments aim to detect ultra-high energy neutrinos. Many of them rely on detecting either the regenerated tau neutrino, or a tau decay shower. Both of these signatures can be affected by the polarization of the tau through the energy distribution of the secondary particles produced from the tau's decay. While taus produced in weak interactions are nearly 100 percent polarized, it is expected that taus experience some depolarization due to electromagnetic interactions in the Earth. In this paper, for the first time we quantify the depolarization of taus in electromagnetic energy loss. We find that tau depolarization has only small effects on the final energy of tau neutrinos or taus produced by high energy tau neutrinos incident on the Earth. Tau depolarization can be directly implemented in Monte Carlo simulations such as nuPyProp and TauRunner.

VTSCat is the catalog of high-level data products from all publications of the VERITAS collaboration. The VTSCat data collection contains: high-level data like spectral flux points, light curves, spectral fits in human- and machine-readable yaml and ecsv file format tabled data like upper limits tables from dark matter searches or results on the extragalactic background in ecsv file format sky maps (wherever available) in FITS file format The data collection contains results from gamma-ray measurements only. This is a pre-release for testing and early publications. A forthcoming research note will provide more details on the catalog. Please check the README file and all documentation linked to the README. VTSCat supplements the HEASARC catalogue of VERITAS results (to be published). VTSCat is inspired and derived from gamma-cat. Access: GitHub: https://github.com/VERITAS-Observatory/VERITAS-VTSCat References: VERITAS: https://veritas.sao.arizona.edu/ VER Dictionary of Nomenclature: https://cds.u-strasbg.fr/cgi-bin/Dic-Simbad?/17350620

Tau neutrinos are the least studied particle in the Standard Model. This whitepaper discusses the current and expected upcoming status of tau neutrino physics with attention to the broad experimental and theoretical landscape spanning long-baseline, beam-dump, collider, and astrophysical experiments. This whitepaper was prepared as a part of the NuTau2021 Workshop.

An accurate modeling of neutrino flux attenuation and the distribution of leptons they produce in transit through the Earth is an essential component to determine neutrino flux sensitivities of underground, sub-orbital and space-based detectors. Through neutrino oscillations over cosmic distances, astrophysical neutrino sources are expected to produce nearly equal fluxes of electron, muon and tau neutrinos. Of particular interest are tau neutrinos that interact in the Earth at modest slant depths to produce tau-leptons. Some g-leptons emerge from the Earth and decay in the atmosphere to produce extensive air showers. Future balloon-borne and satellite-based optical Cherenkov neutrino telescopes will be sensitive to upward air showers from tau neutrino induced tau-lepton decays. We present nuPyProp, a python code that is part of the nuSpaceSim package. nuPyProp generates look-up tables for exit probabilities and energy distributions for nu(tau) -> tau and nu(mu) -> mu propagation in the Earth. This flexible code runs with either stochastic or continuous electromagnetic energy losses for the lepton transit through the Earth. Current neutrino cross section models and energy loss models are included along with templates for user input of other models. Results from nuPyProp are compared with other recent simulation packages for neutrino and charged lepton propagation. Sources of modeling uncertainties are described and quantified.

We describe a new comprehensive, end-to-end simulation package for the modeling of the extensive air shower (EAS) signals from very-high energy (above a PeV) cosmic neutrinos applicable to sub-orbital and space-based observations. The goal is to provide an efficient and practical cosmic neutrino EAS signal generation modeling package to the community that will provide a standard to gauge the neutrino measurement performance of these experiments and aid in their development. The modeling will be performed in such a way to easily be used to provide the neutrinoinduced EAS signals delivered to a specific altitude for a given instrumental field-of-view and orientation. In this paper, we discuss the modeling of tau neutrino interactions inside the Earth, propagating the tau-leptons into the atmosphere, modeling the decays, forming composite EASs, generating the air fluorescence, Cherenkov, and radio signals, and the propagation through the atmosphere. Future work on the modeling of atmospheric transmission and scattering effects will include consideration of the uncertainties and more robust modeling of atmospheric and UHECR backgrounds. Additionally, the framework will allow for the calculation of the sky coverage, the pointing requirements for target-of-opportunity follow up observations of transients, and the inclusion of different neutrino interaction cross-sections to allow for the modeling of non-standard physical processes.

This work looks at some definitive signatures of magnetars, in particular of period closures accompanied by a decline of X-ray radiation in two models. We review some of the previous works which are based on the well-known dynamo model in which the star is born with a period of a few milliseconds at high temperatures. In such a convection regime, the dynamo mechanism can amplify the magnetic fields to the magnetar value. This is in contrast to a screened core model which posits that a high-density phase transition occurs in the inner core of magnetars that dynamically aligns all the neutron magnetic moments producing a large magnetic field in the core. The accompanying change of flux gives rise to shielding or screening currents in the surrounding high conductivity plasma that do not permit the field to exit to the surface. Ambipolar diffusion then transports the field to the crust dissipating energy in neutrinos and X-rays. The upwelling field cleaves the crust resulting in flares and X-ray radiation from Ohmic dissipation in the crust till the screening currents are damped and the surface polar field attains its final value. In the dynamo model, the polar magnetic field decreases with time, whereas in our screened model it increases to its final value. One consequence of this is that in the latter model, as a function of time and period, the ratio of the dipole radiation loss,. E to the X-ray luminosity, L-X, is a 'U' curve, indicating that it is the exponential decline in L-X that brings closure to the spin periods that are observed for magnetars.

This work looks at some definitive signatures of magnetars, in particular of period closures accompanied by a decline of X-ray radiation in two models. We review some of the previous works which are based on the well known dynamo model in which the star is born with a period of a few milliseconds at high temperatures. In such a convection regime the dynamo mechanism can amplify the the magnetic fields to the magnetar value. This is in contrast to a screened core model which posits that a high density phase transition occurs in the inner core of magnetars that dynamically aligns all the neutron magnetic moments producing a large magnetic field in the core. The accompanying change of flux gives rise to shielding or screening currents in the surrounding high conductivity plasma that do not permit the field to exit to the surface. Ambipolar diffusion then transports the field to the crust dissipating energy in neutrinos and X-rays. The up-welling field cleaves the crust resulting in flares and X-ray radiation from ohmic dissipation in the crust till the screening currents are spent and the surface polar field attains its final value. In the dynamo model the polar magnetic field decreases with time whereas in our screened model it increases to its final value. One consequence of this is that in the latter model, as a function of time and period, the ratio of the dipole radiation loss, Ė to the X-ray luminosity, LX , is a ‘U’ curve, indicating that it is the exponential decline in LX , that brings closure to the periods that are observed for magnetars.