New analysis of the SN 1987A neutrinos with a flexible spectral shape

We analyze the neutrino events from the supernova (SN) 1987A detected by the Kamiokande II (KII) and Irvine-Michigan-Brookhaven (IMB) experiments. For the time-integrated flux we assume a quasi-thermal spectrum of the form $(E/E_0)^\alpha e^{-(\alpha+1)E/E_0}$ where $\alpha$ plays the role of a spectral index. This simple representation not only allows one to fit the total energy $E_{\rm tot}$ emitted in $\bar\nu_e$ and the average energy , but also accommodates a wide range of shapes, notably anti-pinched spectra that are broader than a thermal distribution. We find that the pile-up of low-energy events near threshold in KII forces the best-fit value for $\alpha$ to the lowest value of any assumed prior range. This applies to the KII events alone as well as to a common analysis of the two data sets. The preference of the data for an ``unphysical'' spectral shape implies that one can extract meaningful values for and $E_{\rm tot}$ only if one fixes a prior value for $\alpha$. The tension between the KII and IMB data sets and theoretical expectations for $$ is not resolved by an anti-pinched spectrum.Comment: to appear in PRD (6 pages, 6 eps figures

Hydrochemical characterization of a mine water geothermal energy resource in NW Spain

Abandoned and flooded mine networks provide underground reservoirs of mine water that can be used as a renewable geothermal energy source. A complete hydrochemical characterization of mine water is required to optimally design the geothermal installation, understand the hydraulic behavior of the water in the reservoir and prevent undesired effects such as pipe clogging via mineral precipitation. Water pumped from the Barredo-Figaredo mining reservoir (Asturias, NW Spain), which is currently exploited for geothermal use, has been studied and compared to water from a separate, nearby mountain mine and a river that receives mine water discharge and partially infiltrates into the mine workings. Although the hydrochemistry was altered during the flooding process, the deep mine waters are currently near neutral, net alkaline, high metal waters of Na-HCO3 type. Isotopic values suggest that mine waters are closely related to modern meteoric water, and likely correspond to rapid infiltration. Suspended and dissolved solids, and particularly iron content, of mine water results in some scaling and partial clogging of heat exchangers, but water temperature is stable (22 °C) and increases with depth, so, considering the available flow (> 100 L s− 1), the Barredo-Figaredo mining reservoir represents a sustainable, long-term resource for geothermal use

Bayesian Analysis of the Polarization of Distant Radio Sources: Limits on Cosmological Birefringence

A recent study of the rotation of the plane of polarization of light from 160 cosmological sources claims to find significant evidence for cosmological anisotropy. We point out methodological weaknesses of that study, and reanalyze the same data using Bayesian methods that overcome these problems. We find that the data always favor isotropic models for the distribution of observed polarizations over counterparts that have a cosmological anisotropy of the type advocated in the earlier study. Although anisotropic models are not completely ruled out, the data put strong lower limits on the length scale $\lambda$ (in units of the Hubble length) associated with the anisotropy; the lower limits of 95% credible regions for $\lambda$ lie between 0.43 and 0.62 in all anisotropic models we studied, values several times larger than the best-fit value of $\lambda \approx 0.1$ found in the earlier study. The length scale is not constrained from above. The vast majority of sources in the data are at distances closer than 0.4 Hubble lengths (corresponding to a redshift of $\approx$0.8); the results are thus consistent with there being no significant anisotropy on the length scale probed by these data.Comment: 8 pages, 3 figures; submitted to Phys. Rev.

Bayesian inference on compact binary inspiral gravitational radiation signals in interferometric data

Presented is a description of a Markov chain Monte Carlo (MCMC) parameter estimation routine for use with interferometric gravitational radiational data in searches for binary neutron star inspiral signals. Five parameters associated with the inspiral can be estimated, and summary statistics are produced. Advanced MCMC methods were implemented, including importance resampling and prior distributions based on detection probability, in order to increase the efficiency of the code. An example is presented from an application using realistic, albeit fictitious, data.Comment: submitted to Classical and Quantum Gravity. 14 pages, 5 figure

Optimal strategies for gravitational wave stochastic background searches in pulsar timing data

A low frequency stochastic background of gravitational waves may be detected by pulsar timing experiments in the next five to ten years. Using methods developed to analyze interferometric gravitational wave data, in this paper we lay out the optimal techniques to detect a background of gravitational waves using a pulsar timing array. We show that for pulsar distances and gravitational wave frequencies typical of pulsar timing experiments, neglecting the effect of the metric perturbation at the pulsar does not result in a significant deviation from optimality. We discuss methods for setting upper limits using the optimal statistic, show how to construct skymaps using the pulsar timing array, and consider several issues associated with realistic analysis of pulsar timing data.Comment: 20 pages, 6 figures. Added figure with sky sensitivity for Parkes Pulsar Timing Array, included dipole overlap reduction function and derivation in appendix, extended likelihood discussio

Spin-Flavour Oscillations and Neutrinos from SN1987A

The neutrino signal from SN1987A is analysed with respect to spin-flavour oscillations between electron antineutrinos, $\bar{\nu}_{e}$, and muon neutrinos, $\nu_{\mu}$, by means of a maximum likelihood analysis. Following Jegerlehner et al. best fit values for the total energy released in neutrinos, $E_t$, and the temperature of the electron antineutrino, $T_{\bar{\nu}_{e}}$, for a range of mixing parameters and progenitor models are calculated. In particular the dependence of the inferred quantities on the metallicity of the supernova is investigated and the uncertainties involved in using the neutrino signal to determine the neutrino magnetic moment are pointed out.Comment: 14 pages, RevTeX, 4 figures, to appear in Physical Review

Bayesian analysis of neutrinos observed from supernova SN 1987A

We present a Bayesian analysis of the energies and arrival times of the neutrinos from supernova SN 1987A detected by the Kamiokande II, IMB, and Baksan detectors, and find strong evidence for two components in the neutrino signal: a long time scale component from thermal Kelvin-Helmholtz cooling of the nascent neutron star, and a brief (~< 1 s), softer component similar to that expected from emission by accreting material in the delayed supernova scenario. In the context of this model, we show that the data constrain the electron antineutrino rest mass to be less than 5.7 eV with 95% probability. Our analysis takes advantage of significant advances that have occured in the years since the detections in both our understanding of the supernova mechanism and our ability to analyze sparse data. As a result there are substantial differences between our inferences and those found in earlier studies. We find that two-component models for the neutrino signal make the data >100 times more probable than single-component models. In addition, the radius and binding energy of the nascent neutron star implied by single-component models deviates significantly from the values predicted by current neutron star models, whereas those implied by models with an accretion component are in complete agreement with the predictions. As a result, two-component models are hundreds to thousands of times more probable than single-component models. The neutrino data thus provide the first direct observational evidence in favor of the delayed supernova scenario over the prompt scenario. (Abridged abstract)Comment: 46 pages, 12 figures, RevTeX; for submission to Physical Review

Progress in the physics of massive neutrinos

The current status of the physics of massive neutrinos is reviewed with a forward-looking emphasis. The article begins with the general phenomenology of neutrino oscillations in vacuum and matter and documents the experimental evidence for oscillations of solar, reactor, atmospheric and accelerator neutrinos. Both active and sterile oscillation possibilities are considered. The impact of cosmology (BBN, CMB, leptogenesis) and astrophysics (supernovae, highest energy cosmic rays) on neutrino observables and vice versa, is evaluated. The predictions of grand unified, radiative and other models of neutrino mass are discussed. Ways of determining the unknown parameters of three-neutrino oscillations are assessed, taking into account eight-fold degeneracies in parameters that yield the same oscillation probabilities, as well as ways to determine the absolute neutrino mass scale (from beta-decay, neutrinoless double-beta decay, large scale structure and Z-bursts). Critical unknowns at present are the amplitude of \nu_\mu to \nu_e oscillations and the hierarchy of the neutrino mass spectrum; the detection of CP violation in the neutrino sector depends on these and on an unknown phase. The estimated neutrino parameter sensitivities at future facilities (reactors, superbeams, neutrino factories) are given. The overall agenda of a future neutrino physics program to construct a bottom-up understanding of the lepton sector is presented.Comment: 111 pages, 35 figures. Update