Radio Cherenkov signals from the Moon: Neutrinos and cosmic rays

Abstract

Neutrino production of radio Cherenkov signals in the Moon is the object of radio telescope observations. Depending on the energy range and detection parameters, the dominant contribution to the neutrino signal may come from interactions of the neutrino on the Moon facing the telescope, rather than neutrinos that have traversed a portion of the Moon. Using the approximate analytic expression of the effective lunar aperture from a recent paper by Gayley, Mutel and Jaeger, we evaluate the background from cosmic ray interactions in the lunar regolith. We also consider the modifications to the effective lunar aperture from generic non-standard model neutrino interactions. A background to neutrino signals are radio Cherenkov signals from cosmic ray interactions. For cosmogenic neutrino fluxes, neutrino signals will be difficult to observe because of low neutrino flux at the high energy end and large cosmic ray background in the lower energy range considered here. We show that lunar radio detection of neutrino interactions is best suited to constrain or measure neutrinos from astrophysical sources and probe non-standard neutrino-nucleon interactions such as microscopic black hole production.

Prospects of probing the radio emission of lunar UHECRv events

“…As we will see this is reflected in the event rate predictions of the two frequency regimes. For ground-based observation, minimum detectable electric field is set at 0.01 µV/m per MHz, a typical number which has been used in (Gayley et al, 2009) and (Jeong et al, 2012). For simplicity, we assume the bandwidth and Tsys of such an array to be the same as those for a lunar lander or lunar orbiter antenna.…”

Sensitivity of lunar particle-detection experiments

“…I estimate the limits or potential limits set by some past and near-future lunar Askaryan experiments using an analytic model for the particle aperture [18,23,24]. To reflect the effects of small-scale surface roughness, I use the only extant model [13], which represents the aperture as a linear combination of two extreme cases: one in which these effects are ignored, and one in which they are maximised, by representing the surface as a series of small-scale facets with uncorrelated slopes.…”

LUNASKA neutrino search with the Parkes and ATCA telescopes

“…UHE neutrinos may, in addition to the usual weak interactions, interact via the formation and subsequent decay of a microscopic black hole, which leads to a larger cross-section than expected from standard model physics [21,22]. James et al [6] and Jeong et al [15] find that this strongly enhances the aperture of lunar neutrino experiments; consequently, some combinations of models of enhanced cross-sections (from black hole formation) and enhanced neutrino fluxes (from top-down UHE CR origin models) may already be excluded by current experiments.…”

“…Such neutrino spectra are not expected from interactions of cosmic rays (CRs) with the cosmic microwave background [12], but may arise from top-down models of UHE CRs, in which they may originate from topological defects such as cusps and kinks in cosmic strings [13,14]. In the absence of neutrinos from top-down models, lunar experiments are likely to, as they become more sensitive, detect CRs directly before they detect neutrinos [15].…”