53586794
LUNASKA neutrino search with the Parkes and ATCA telescopes
The Moon is used as a target volume for ultra-high energy neutrino searches with terrestrial radio telescopes. The LUNASKA project has conducted observations with the Parkes and ATCA telescopes; and, most recently, with both of them in combination. We present an analysis of the data obtained from these searches, including validation and calibration results for the Parkes-ATCA experiment, as well as a summary of prospects for future observations.
118954604
LUNASKA simultaneous neutrino searches with multiple telescopes
ICRC 2011 : 32nd International Cosmic Ray Conference 11-18 August, Beijing, China, 11 augustus 2011
122673987
Coherent Cherenkov radio emission from EeV showers in dense media through thinned simulations
Abstract We explore the feasibility of applying “thinning techniques” to the simulation of EeV electromagnetic showers in ice, salt, and the regolith of the Moon. By comparing the results of thinned showers to full simulations, we show that thinning techniques keep a good level of accuracy in the relevant shower and radio observables, and allow a considerable reduction in computing time. We apply thinning techniques to the simulation of EeV electromagnetic showers including the Landau–Pomeranchuk–Migdal effect. Our study is of the utmost importance for the determination of the sensitivity to extremely energetic neutrinos of experiments looking for radiopulses in dense media.
119071284
Status report and future prospects on LUNASKA lunar observations with ATCA
Abstract LUNASKA (Lunar UHE Neutrino Astrophysics with the Square Kilometre Array) is a theoretical and experimental project developing the lunar Cherenkov technique for the next generation of giant radio-telescope arrays. Here we report on a series of observations with ATCA (the Australia Telescope Compact Array). Our current observations use three of the six 22 m ATCA antennas with a 600 MHz bandwidth at 1.2–1.8 GHz, analogue dedispersion filters to correct for the typical night-time ionospheric dispersion, and state-of-the-art 2 GHz FPGA-based digital pulse detection hardware. We have observed so as to maximise the UHE neutrino sensitivity in the region surrounding the galactic centre and to Centaurus A, to which current limits on the highest-energy neutrinos are relatively weak.
31685649
SEARCHES FOR POINT-LIKE AND EXTENDED NEUTRINO SOURCES CLOSE TO THE GALACTIC CENTER USING THE ANTARES NEUTRINO TELESCOPE
A search for cosmic neutrino sources using six years of data collected by the ANTARES neutrino telescope has been performed. Clusters of muon neutrinos over the expected atmospheric background have been looked for. No clear signal has been found. The most signal-like accumulation of events is located at equatorial coordinates RA=$-$46.8$^{\circ}$ and Dec=$-$64.9$^{\circ}$ and corresponds to a 2.2$\sigma$ background fluctuation. In addition, upper limits on the flux normalization of an E$^{-2}$ muon neutrino energy spectrum have been set for 50 pre-selected astrophysical objects. Finally, motivated by an accumulation of 7 events relatively close to the Galactic Centre in the recently reported neutrino sample of the IceCube telescope, a search for point sources in a broad region around this accumulation has been carried out. No indication of a neutrino signal has been found in the ANTARES data and upper limits on the flux normalization of an E$^{-2}$ energy spectrum of neutrinos from point sources in that region have been set. The 90% confidence level upper limits on the muon neutrino flux normalization vary between 3.5 and 5.1$\times$10$^{-8}$ GeV$\,$cm$^{-2}$s$^{-1}$, depending on the exact location of the source.
117844015
The endpoint formalism for the calculation of electromagnetic radiation and its applications in astroparticle physics
We present the "endpoint" formalism for the calculation of electromagnetic radiation and illustrate its applications in astroparticle physics. We use the formalism to explain why the coherent radiation from the Askaryan effect is not in general Cherenkov radiation, as the emission directly results from the time-variation of the net charge in the particle shower. Secondly, we illustrate how the formalism has been applied in the air shower radio emission code REAS3 to unify the microscopic and macroscopic views of radio emission from extensive air showers. Indeed, the formalism is completely universal and particularly well-suited for implementation in Monte Carlo codes in the time- and frequency-domains. It easily reproduces well-known "classical mechanisms" such as synchrotron radiation, Vavilov-Cherenkov radiation and transition radiation in the adequate limits, but has the advantage that it continues to work in realistic, complex situations, where the "classical mechanisms" tend to no longer apply and adhering to them can result in misleading interpretations.
17030416
A New Population of Old Stars
We report the results of a coherent study of three chemically anomalous metal-poor ([Fe/H] ~ -2) stars. These objects exhibit unusually low abundances of Mg, Si, Ca (alpha-elements) and Sr, Y, and Ba (neutron-capture elements). Our analyses confirm and expand upon earlier reports of atypical abundances in BD+80~245, G4-36, and CS22966-043. We also find that the latter two stars exhibit enhanced abundances of Cr, Mn, Ni, and Zn (iron-peak elements), along with what appears to be large abundances of Ga, with respect to the abundance of iron. Comparing the chemical abundances of these stars to supernova model yields, we derive supernovae ratios of Type Ia versus Type II events in the range of 0.6 <= (N_Ia/N_II) <= 1.3. Whereas, for the Sun, we derive supernovae ratios in good agreement with those found in the literature: 0.18 +/- 0.01 < (N_Ia/N_II)_sun < 0.25 +/- 0.06. Given the relatively low metallicity and high (N_Ia/N_II) ratios of the low-alpha stars studied here, these objects may have witnessed, or been born from material produced in the yields of the earliest supernova Type Ia events.
53048052
TANAMI Blazars in the IceCube PeV Neutrino Fields
ABSTRACT The IceCube Collaboration has announced the discovery of a neutrino ﬂux in excess of the atmospheric background. Due to thesteeply falling atmospheric background spectrum, events at PeV energies are most likely of extraterrestrial origin. We present themultiwavelength properties of the six radio brightest blazars positionally coincident with these events using contemporaneous data ofthe TANAMI blazar sample, including high-resolution images and spectral energy distributions. Assuming the X-ray to -ray emissionoriginates in the photoproduction of pions by accelerated protons, the integrated predicted neutrino luminosity of these sources is largeenough to explain the two detected PeV events. Key words. neutrinos – galaxies: active – quasars: general 1. Introduction The detection of neutrinos at PeV energies in excess of the at-mospheric background reported by the IceCube Collaboration(Aartsen et al. 2013; IceCube Collaboration 2013) has prompteda quest to identify their extraterrestrial sources. The two eventswith PeV energies (event 20, dubbed ‘Ernie’ and event 14,‘Bert’, hereafter E20 and E14), detected between May 2010 andMay 2012
118614292
Upcoming neutrino oscillation experiments at Fermilab
Two experiments to investigate neutrino oscillations are now under construction at Fermilab. An overview of the experiments is given.
181751932
Summary of the triggering, DAQ, and analysis working group
7763998
Swift UVOT detection of GRB 050318
We present observations of GRB 050318 by the Ultraviolet/Optical Telescope (UVOT) on board the Swift observatory. The data are the first detections of a gamma-ray burst (GRB) afterglow decay by the UVOT instrument, launched specifically to open a new window on these transient sources. We showcase UVOT's ability to provide multicolor photometry and the advantages of combining UVOT data with simultaneous and contemporaneous observations from the high-energy detectors on the Swift spacecraft. Multiple filters covering 1800-6000 A reveal a red source with a spectral slope steeper than the simultaneous X-ray continuum. Spectral fits indicate that the UVOT colors are consistent with dust extinction by systems at z = 1.2037 and 1.4436, redshifts where absorption systems have been preidentified. However, the data can be most easily reproduced with models containing a foreground system of neutral gas redshifted by z = 2.8 ± 0.3. For both of the above scenarios, spectral and decay slopes are, for the most part, consistent with fireball expansion into a uniform medium, provided a cooling break occurs between the energy ranges of the UVOT and Swift's X-ray instrumentation.