We derive analytic expressions, and approximate them in closed form, for the effective detection aperture for Cerenkov radio emission from ultra-high-energy neutrinos striking the Moon. The resulting apertures are in good agreement with recent Monte Carlo simulations and support the conclusion of James & Protheroe (2009) that neutrino flux upper limits derived from the GLUE search were too low by an order of magnitude. We also use our analytic expressions to derive scaling laws for the aperture as a function of observational and lunar parameters. We find that at low frequencies downward-directed neutrinos always dominate, but at higher frequencies, the contribution from upward-directed neutrinos becomes increasingly important, especially at lower neutrino energies. Detecting neutrinos from Earth near the GZK regime will likely require radio telescope arrays with extremely large collecting area (A e ∼ 10 6 m 2 ) and hundreds of hours exposure time. Higher energy neutrinos are most easily detected using lower frequencies. Lunar surface roughness is a decisive factor for obtaining detections at higher frequencies (ν ∼ > 300 MHz) and higher energies (E ∼ > 10 21 eV).

In the past decade there have been several attempts to detect ultra high energy (UHE) neutrinos by searching for radioĈerenkov bursts in terrestrial ice or the lunar regolith. So far these searches have yielded no detections, but the inferred flux upper limits have started to constrain physical models for UHE neutrino generation.This thesis is a description of the Radio EVLA Search for UHE Neutrinos (RESUN) experiment, aimed at further limiting isotropic and point-source production mod- Abstract Approved: Thesis Supervisor

We report the results of a low frequency radio variability and slow transient search using archival observations from the Very Long Array. We selected six 325 MHz radio observations from the spring of 2006, each centered on the Spitzer-Space-Telescope Wide-area Infrared Extragalactic Survey (SWIRE) Deep Field: 1046+59. Observations were spaced between one day to three months, with a typical single-epoch peak flux sensitivity below 0.2 mJy beam −1 near the field pointing center. We describe the observation parameters, data post-processing, and search methodology used to identify variable and transient emission. Our search revealed multiple variable sources and the presence of one, day-scale transient event with no apparent astronomical counterpart. This detection implies a transient rate of 1 ± 1 event per 6.5 deg 2 per 72 observing hours in the direction of 1046+59 and an isotropic transient surface density Σ = 0.12 deg −2 at 95% confidence for sources with average peak flux density higher than 2.1 mJy over 12 hr.

[1] We calculate growth rates and corresponding gains for right-hand circularly polarized extraordinary (RX) and left-hand ordinary circularly polarized (LO) mode radiation associated with the cyclotron maser instability (CMI) for parameterized horseshoe electron velocity distributions. The velocity distribution function was modeled to closely fit the electron distribution functions observed in the auroral cavity. We systematically varied the model parameters as well as the propagation direction to study the dependence of growth rates on model parameters. The growth rate depends strongly on loss cone opening angle, which must be less than 90°for significant CMI growth. The growth rate is sharply peaked for perpendicular radiation (k k = 0), with a full width at half maximum 1.7°, in good agreement with observed k-vector orientations and numerical simulations. The fractional bandwidth varied between 10 À4 and 10 À2 , depending most strongly on propagation direction. This range encompasses nearly all observed fractional auroral kilometric radiation (AKR) burst bandwidths. We find excellent agreement between the computed RX mode emergent intensities and observed AKR intensities assuming convective growth length L c % 20-40 km and group speed 0.15c. The only computed LO mode growth rates compatible observed LO mode radiation levels occurred for number densities more than 100 times the average energetic electron densities measured in auroral cavities. This implies that LO mode radiation is not produced directly by the CMI mechanism but more likely results from mode conversion of RX mode radiation. We find that perturbation of the model velocity distribution by large ion solitary waves (ion holes) can enhance the growth rate by a factor of 2-4. This will result in a gain enhancement more than 40 dB depending on the convective growth length within the structure. Similar enhancements may be caused by strong electromagnetic ion cyclotron waves.

New observations of Jupiter's decametric radio emissions have been made with the Long Wavelength Array Station 1 (LWA1), which is capable of making high-quality observations as low as 11 MHz. Full Stokes parameters were determined for bandwidths of 16 MHz. Here we present the first LWA1 results for the study of six Io-related events at temporal resolutions as fine as 0.25 ms. LWA1 data show excellent spectral detail in Jovian DAM such as simultaneous left-hand circular (LHC) and right-hand circular (RHC) polarized Io-related arcs and source envelopes, modulation lane features, S-burst structures, narrow band N events, and interactions between S bursts and N events. The sensitivity of the LWA1 combined with the low-radio-frequency interference environment allow us to trace the start of the LHC Io-C source region to much earlier CML III than typically found in the literature. We find that the Io-C starts as early as CML III = 230• at frequencies near 11 MHz. This early start of the Io-C emission may be valuable for refining models of the emission mechanism. We also detect modulation lane structures that appear continuous across LHC and RHC emissions, suggesting that both polarizations may originate from the same hemisphere of Jupiter. We present a study of rare S bursts detected during an Io-D event and show that drift rates are consistent with those from other Io-related sources. Finally, S-N burst events are seen in high spectral and temporal resolution and our data strongly support the cospatial origins of these events.