Search for high-energy neutrinos from gravitational wave event GW151226 and candidate LVT151012 with ANTARES and IceCube
Physical Review D American Physcial Society 96:2 (2017) 022005
Abstract:
The Advanced LIGO observatories detected gravitational waves from two binary black hole mergers during their first observation run (O1). We present a high-energy neutrino follow-up search for the second gravitational wave event, GW151226, as well as for gravitational wave candidate LVT151012. We find 2 and 4 neutrino candidates detected by IceCube, and 1 and 0 detected by ANTARES, within $\pm500$ s around the respective gravitational wave signals, consistent with the expected background rate. None of these neutrino candidates are found to be directionally coincident with GW151226 or LVT151012. We use non-detection to constrain isotropic-equivalent high-energy neutrino emission from GW151226 adopting the GW event's 3D localization, to less than $2\times 10^{51}-2\times10^{54}$ erg.High redshift radio galaxies and divergence from the CMB dipole
Monthly Notices of the Royal Astronomical Society Oxford University Press 471:1 (2017) 1045-1055
Abstract:
Previous studies have found our velocity in the rest frame of radio galaxies at high redshift to be much larger than that inferred from the dipole anisotropy of the cosmic microwave background. We construct a full sky catalogue, NVSUMSS, by merging the NRAO VLA Sky Survey and the Sydney University Molonglo Sky Survey catalogues and removing local sources by various means including cross-correlating with the 2MASS Redshift Survey catalogue. We take into account both aberration and Doppler boost to deduce our velocity from the hemispheric number count asymmetry, as well as via a three-dimensional linear estimator. Both its magnitude and direction depend on cuts made to the catalogue, e.g. on the lowest source flux; however these effects are small. From the hemispheric number count asymmetry we obtain a velocity of 1729 ± 187 km s−1, i.e. about four times larger than that obtained from the cosmic microwave background dipole, but close in direction, towards RA=149° ± 2°, Dec. = −17° ± 12°. With the three-dimensional estimator, the derived velocity is 1355 ± 174 km s−1 towards RA = 141° ± 11°, Dec. = −9° ± 10°. We assess the statistical significance of these results by comparison with catalogues of random distributions, finding it to be 2.81σ (99.75 per cent confidence).Search for sterile neutrino mixing using three years of IceCube DeepCore data
Physical Review D American Physical Society 95:11 (2017) 112002
Abstract:
We present a search for a light sterile neutrino using three years of atmospheric neutrino data from the DeepCore detector in the energy range of approximately 10-60 GeV. DeepCore is the low-energy subarray of the IceCube Neutrino Observatory. The standard three-neutrino paradigm can be probed by adding an additional light (Δm412∼1 eV2) sterile neutrino. Sterile neutrinos do not interact through the standard weak interaction and, therefore, cannot be directly detected. However, their mixing with the three active neutrino states leaves an imprint on the standard atmospheric neutrino oscillations for energies below 100 GeV. A search for such mixing via muon neutrino disappearance is presented here. The data are found to be consistent with the standard three-neutrino hypothesis. Therefore, we derive limits on the mixing matrix elements at the level of |Uμ4|2 < 0.11 and |Uτ4|2 < 0.15 (90% C.L.) for the sterile neutrino mass splitting Δm412=1.0 eV2.Exploring the Universe with Neutrinos: Recent Results from IceCube
Nuclear and Particle Physics Proceedings Elsevier 287 (2017) 139-142
Astrophysical neutrinos and cosmic rays observed by IceCube
Advances in Space Research (2017)