14 research outputs found
Observational Constraints on the Ultra-high Energy Cosmic Neutrino Flux from the Second Flight of the ANITA Experiment
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 the payload
sensitivity, efficiency, and a flight trajectory over deeper ice. 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 1-1000 EeV cosmic neutrinos, excluding several current
cosmogenic neutrino models.Comment: 6 pages, 5 figures, submitted to Phys. Rev.
Ultra-Relativistic Magnetic Monopole Search with the ANITA-II Balloon-borne Radio Interferometer
We have conducted a search for extended energy deposition trails left by
ultra-relativistic magnetic monopoles interacting in Antarctic ice. The
non-observation of any satisfactory candidates in the 31 days of accumulated
ANITA-II flight data results in an upper limit on the diffuse flux of
relativistic monopoles. We obtain a 90% C.L. limit of order
10^{-19}/(cm^2-s-sr) for values of Lorentz boost factor 10^{10}<gamma at the
anticipated energy E=10^{16} GeV. This bound is stronger than all previously
published experimental limits for this kinematic range.Comment: updated to version accepted by Phys. Rev.
Gravity and Electromagnetism with -type Coupling and Magnetic Monopole Solutions
We investigate -type coupling of electromagnetic fields to
gravity. After we derive field equations by a first order variational principle
from the Lagrangian formulation of the non-minimally coupled theory, we look
for static, spherically symmetric, magnetic monopole solutions. We point out
that the solutions can provide possible geometries which may explain the
flatness of the observed rotation curves of galaxies.Comment: 10 page
The First Limits on the Ultra-high Energy Neutrino Fluence from Gamma-ray Bursts
We set the first limits on the ultra-high energy (UHE) neutrino fluence at
energies greater than 10^9 GeV from gamma-ray bursts (GRBs) based on data from
the second flight of the ANtarctic Impulsive Transient Antenna (ANITA). During
the 31 day flight of ANITA-II, 26 GRBs were recorded by Swift or Fermi. Of
these, we analyzed the 12 GRBs which occurred during quiet periods when the
payload was away from anthropogenic activity. In a blind analysis, we observe 0
events on a total background of 0.0044 events in the combined prompt window for
all 12 low-background bursts. We also observe 0 events from the remaining 14
bursts. We place a 90% confidence level limit on the E^-4 prompt neutrino
fluence of 2.5x10^17 GeV^3/cm^2 between 10^8 and 10^12 GeV from GRB090107A.
This is the first reported limit on the UHE neutrino fluence from GRBs above
10^9 GeV, and the strongest limit above 10^8 GeV.Comment: 4 pages, 2 figures, submitted to Ap
Erratum: Observational Constraints on the Ultrahigh Energy Cosmic Neutrino Flux from the Second Flight of the ANITA Experiment
This is an erratum to the original paper published in Physical Review D , 82 (2), article no. 022004, on 16 July 2010 (DOI: 10.1103/PhysRevD.82.022004)
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