Observational constraints on the ultrahigh energy cosmic neutrino flux from the second flight of the ANITA experiment

Abstract

The Antarctic Impulsive Transient Antenna (ANITA) completed its second Long Duration Balloon flight in January 2009, with 31 days aloft (28.5 live days) over Antarctica. ANITA searches for impulsive coherent radio Cherenkov emission from 200 to 1200 MHz, arising from the Askaryan charge excess in ultra-high energy neutrino-induced cascades within Antarctic ice. This flight included significant improvements over the first flight in payload sensitivity, efficiency, and flight trajectory. Analysis of in-flight calibration pulses from surface and sub-surface locations verifies the expected sensitivity. In a blind analysis, we find 2 surviving events on a background, mostly anthropogenic, of 0.97 ± 0.42 events. We set the strongest limit to date for 10 18 − 10 21 eV cosmic neutrinos, excluding several current cosmogenic neutrino models.

Background studies for acoustic neutrino detection at the South Pole

“…The even broader light gray band includes additional uncertainties due to the choice of different acoustic models. Experimental limits on the flux of ultra high energy neutrinos are from ANITA II [13], FORTE [14], GLUE [15], SAUND II [26], ACoRNE [16]. For model reference see [24,25].…”

Measurement of the Muon Atmospheric Production Depth with the Water Cherenkov Detectors of the Pierre Auger Observatory

“…[38,39,40,41] and neutrinos (right) [52] obtained from the Pierre Auger Observatory. The data are shown together with the current limits from other experiments [53,54,55,56,57,58,59] and some examples of predicted fluxes.…”

Upward-Pointing Cosmic-Ray-like Events Observed with ANITA

“…Such simulations have been applied to neutrino [4,5] and cosmic ray [2,11] analyses. In this study, we take a simplified approach with the objective of setting an upper bound to the sensitivity of ANITA.…”

“…The competing hypotheses for the τ-lepton air shower candidate are that it is either a downgoing cosmic ray extensive air shower with its radio impulsive emission reflected off the surface of the ice (see [2]) or an anthropogenic background (see [3,4,5]). The τ-lepton decay is favored over the down-going cosmic ray hypothesis due to the polarity of the impulse and the correlation of the polarization vector to the geomagnetic field.…”