12 research outputs found
A search for ultrahigh-energy neutrinos associated with astrophysical sources using the third flight of ANITA
The ANtarctic Impulsive Transient Antenna (ANITA) long-duration balloon experiment is sensitive to interactions of ultrahigh-energy (E>1018 eV) neutrinos in the Antarctic ice sheet. The third flight of ANITA, lasting 22 days, began in December 2014. We develop a methodology to search for energetic neutrinos spatially and temporally coincident with potential source classes in ANITA data. This methodology is applied to several source classes: the potential IceCube-identified neutrino sources TXS 0506+056 and NGC 1068, flaring high-energy blazars reported by the Fermi All-Sky Variability Analysis, gamma-ray bursts, and supernovae. Among searches within the five source classes, one candidate was identified as associated with SN 2015D, although not at a statistically significant level. We proceed to place upper limits on the source classes. We further comment on potential application of this methodology to more sensitive future instruments
An analysis of a tau-neutrino hypothesis for the near-horizon cosmic-ray-like events observed by ANITA-IV
We present the results of a simulation of the acceptance of the Antarctic Impulsive Transient Antenna (ANITA) to possible υτ point source fluxes detected via τ-lepton-induced air showers. This investigation is framed around the detection of four upward-going extensive air shower events observed very close to the horizon in ANITA-IV. These four events as well as the overall diffuse and point source exposure to Earth-skimming υτ are also compared against published ultrahigh-energy neutrino limits from the Pierre Auger Observatory. We find that while these four events were detected at sky coordinates close to ANITA’s maximum υτ sensitivity and were not simultaneously visible by Auger, the implied fluence necessary for ANITA to observe these events is in tension with limits set by Auger across a wide range of energies and is additionally in tension with ANITA’s Askaryan in-ice neutrino channel above 1019 eV
Analysis of a tau neutrino origin for the near-horizon air shower events observed by the fourth flight of the Antarctic Impulsive Transient Antenna
We study in detail the sensitivity of the Antarctic Impulsive Transient Antenna (ANITA) to possible Formula Presented point source fluxes detected via Formula Presented-lepton-induced air showers. This investigation is framed around the observation of four upward-going extensive air shower events very close to the horizon seen in ANITA-IV. We find that these four upgoing events are not observationally inconsistent with Formula Presented-induced EASs from Earth-skimming Formula Presented both in their spectral properties as well as in their observed locations on the sky. These four events as well as the overall diffuse and point source exposure to Earth-skimming Formula Presented are also compared against published ultrahigh-energy neutrino limits from the Pierre Auger Observatory. While none of these four events occurred at sky locations simultaneously visible by Auger, the implied fluence necessary for ANITA to observe these events is in strong tension with limits set by Auger across a wide range of energies and is additionally in tension with ANITA’s Askaryan in-ice neutrino channel above Formula Presented. We conclude by discussing some of the technical challenges with simulating and analyzing these near horizon events and the potential for future observatories to observe similar events
The simulation of the sensitivity of the Antarctic Impulsive Transient Antenna (ANITA) to Askaryan radiation from cosmogenic neutrinos interacting in the Antarctic Ice
A Monte Carlo simulation program for the radio detection of Ultra High Energy
(UHE) neutrino interactions in the Antarctic ice as viewed by the Antarctic
Impulsive Transient Antenna (ANITA) is described in this article. The program,
icemc, provides an input spectrum of UHE neutrinos, the parametrization of the
Askaryan radiation generated by their interaction in the ice, and the
propagation of the radiation through ice and air to a simulated model of the
third and fourth ANITA flights. This paper provides an overview of the icemc
simulation, descriptions of the physics models used and of the ANITA
electronics processing chain, data/simulation comparisons to validate the
predicted performance, and a summary of the impact of published results
Constraints on the ultrahigh-energy cosmic neutrino flux from the fourth flight of ANITA
The ANtarctic Impulsive Transient Antenna (ANITA) NASA long-duration balloon
payload completed its fourth flight in December 2016, after 28 days of flight
time. ANITA is sensitive to impulsive broadband radio emission from
interactions of ultra-high-energy neutrinos in polar ice (Askaryan emission).
We present the results of two separate blind analyses searching for signals
from Askaryan emission in the data from the fourth flight of ANITA. The more
sensitive analysis, with a better expected limit, has a background estimate of
and an analysis efficiency of . The second
analysis has a background estimate of and an analysis
efficiency of . Each analysis found one event in the signal region,
consistent with the background estimate for each analysis. The resulting limit
further tightens the constraints on the diffuse flux of ultra-high-energy
neutrinos at energies above eV.Comment: 11 pages, 7 figure
Comprehensive analysis of anomalous ANITA events disfavors a diffuse tau-neutrino flux origin
Recently, the ANITA collaboration reported on two upward-going extensive air
shower events consistent with a primary particle that emerges from the surface
of the ice. These events may be of origin, in which the neutrino
interacts within the Earth to produce a lepton that emerges from the
Earth, decays in the atmosphere, and initiates an extensive air shower. In this
paper we estimate an upper bound on the ANITA acceptance to a diffuse
flux detected via -lepton-induced air showers within the
bounds of Standard Model (SM) uncertainties. By comparing this estimate with
the acceptance of Pierre Auger Observatory and IceCube and assuming SM
interactions, we conclude that a origin of these events would imply
a neutrino flux at least two orders of magnitude above current bounds.Comment: 12 pages, 7 figure