Tau neutrinos are unique cosmic messengers, especially at extreme energies. When they undergo a charged-current interaction, the short lifetime of the produced tau gives rise to secondary tau ...neutrinos that carry a significant fraction of the primary neutrino energy. Here we apply this effect, known as tau neutrino regeneration, to extremely high energy neutrinos passing through Earth. We find that for most column depths, with the exception of propagation through the core, Earth-traversing tau neutrinos emerge at (PeV) energies. We use these secondaries to estimate the expected signal from cosmogenic fluxes at IceCube and find a non-negligible contribution to the astrophysical component above 1 PeV . We also constrain the anomalous ANITA observations via the accompanying secondaries expected at IceCube. We calculate that ANITA should see fewer than 10−7 events in the reported direction, regardless of assumed source energy spectrum, ruling out the possibility that these events are astrophysical in origin under Standard Model assumptions.
In the past decade IceCube's observations have revealed a flux of astrophysical neutrinos extending to 107GeV. The forthcoming generation of neutrino observatories promises to grant further insight ...into the high-energy neutrino sky, with sensitivity reaching energies up to 1012GeV. At such high energies, a new set of effects becomes relevant, which was not accounted for in the last generation of neutrino propagation software. Thus, it is important to develop new simulations which efficiently and accurately model lepton behavior at this scale. We present TauRunner, a Python-based package that propagates neutral and charged leptons. TauRunner supports propagation between 10GeV and 1012GeV. The package accounts for all relevant secondary neutrinos produced in charged-current tau neutrino interactions. Additionally, tau energy losses of taus produced in neutrino interactions are taken into account, and treated stochastically. Finally, TauRunner is broadly adaptable to divers experimental setups, allowing for user-specified trajectories and propagation media, neutrino cross sections, and initial spectra.
Program title:TauRunner
CPC Library link to program files:https://doi.org/10.17632/82nyd9skhj.1
Developer's repository link:https://github.com/icecube/TauRunner
Licensing provisions: GNU General Public License 3
Programming language:Python
Nature of problem: Propagation of ultra-high energy neutrinos in dense media accounting for various effects associated with ντ and τ± energy losses.
Solution method: Monte Carlo methods.
The Distributed Electronic Cosmic-ray Observatory (DECO) is a cell phone app
that uses a cell phone camera image sensor to detect cosmic-ray particles and
particles from radioactive decay. Images ...recorded by DECO are classified by a
convolutional neural network (CNN) according to their morphology. In this
project, we develop a GEANT4-derived simulation of particle interactions inside
the CMOS sensor using the Allpix$^2$ modular framework. We simulate muons,
electrons, and photons with energy range 10 keV to 100 GeV, and their deposited
energy agrees well with expectations. Simulated events are recorded and
processed in a similar way as data images taken by DECO, and the result shows
both similar image morphology with data events and good quantitative data-Monte
Carlo agreement.
Realtime analyses are necessary to identify the source of high energy neutrinos. As an observatory with a 4\(\pi\) steradian field of view and near-100% duty cycle, the IceCube Neutrino Observatory ...is a unique facility for investigating transients. In 2016, IceCube established a pipeline that uses low-latency data to rapidly respond to astrophysical events that were of interest to the multi-messenger observational community. Here, we describe this pipeline and summarize the results from all of the analyses performed since 2016. We focus not only on those analyses which were performed in response to transients identified using other messengers such as photons and gravitational waves, but also on how this pipeline can be used to constrain populations of astrophysical neutrino transients by following up high-energy neutrino alerts.
On 22 September 2017, IceCube reported a high-energy neutrino event which was found to be coincident with a flaring blazar, TXS 0506+056. This multi-messenger observation hinted at blazars ...contributing to the observed high-energy astrophysical neutrinos and raised a need for extensive correlation studies. Recent work shows that the internal absorption of gamma rays, and their interactions intrinsic to the source and with the extragalactic background, will cause a lack of energetic gamma-ray and neutrino correlation while hinting towards a correlation between neutrinos and lower photon energy observations in the X-ray and radio bands. Studies based on published IceCube alerts and radio observations report a possible radio-neutrino correlation in both gamma-ray bright and gamma-ray dim active galactic nuclei (AGN). However, they have marginal statistical significance due to limited available data. We present a correlation analysis between 15 GHz radio observations of AGN reported in the MOJAVE XV catalog and 10 years of IceCube detector data and discuss the results derived from a time-averaged stacking analysis.
In the past decade IceCube's observations have revealed a flux of astrophysical neutrinos extending to \(10^{7}~\rm{GeV}\). The forthcoming generation of neutrino observatories promises to grant ...further insight into the high-energy neutrino sky, with sensitivity reaching energies up to \(10^{12}~\rm{GeV}\). At such high energies, a new set of effects becomes relevant, which was not accounted for in the last generation of neutrino propagation software. Thus, it is important to develop new simulations which efficiently and accurately model lepton behavior at this scale. We present TauRunner a PYTHON-based package that propagates neutral and charged leptons. TauRunner supports propagation between \(10~\rm{GeV}\) and \(10^{12}~\rm{GeV}\). The package accounts for all relevant secondary neutrinos produced in charged-current tau neutrino interactions. Additionally, tau energy losses of taus produced in neutrino interactions is taken into account, and treated stochastically. Finally, TauRunner is broadly adaptable to divers experimental setups, allowing for user-specified trajectories and propagation media, neutrino cross sections, and initial spectra.
Recent observations of GeV gamma-rays from novae have led to a paradigm shift in the understanding of these objects. While it is now believed that shocks contribute significantly to the energy budget ...of novae, it is still unknown if the emission is hadronic or leptonic in origin. Neutrinos could hold the key to definitively differentiating between these two scenarios, though the energies of such particles would be much lower than are typically targeted with neutrino telescopes. IceCube's densely instrumented DeepCore sub-array provides the ability to reduce the threshold for observation from 1 TeV down to approximately 10 GeV. We will discuss recent measurements in this low energy regime, details of a new sub-TeV selection, and prospects for future searches for transient neutrino emission.
The IceCube DeepCore is a dense infill array of the IceCube Neutrino Observatory at the South Pole. While IceCube is best suited for detecting neutrinos with energies of several 100 GeV and above, ...DeepCore allows to probe neutrinos with lower energies. We focus on a sample of neutrinos with energies above approximately 10 GeV, which was originally optimised for oscillation experiments. Recently, it has been adapted to enable searches for transient sources of astrophysical neutrinos in the sky. In particular, this low-energy dataset can be used to conduct follow-up searches of gravitational wave transients detected by the LIGO-Virgo instruments. A study of this, which complements IceCube's follow-up of gravitational wave events using high-energy neutrino samples, will be discussed here.
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