Angpow: a software for the fast computation of accurate tomographic power spectra

The statistical distribution of galaxies is a powerful probe to constrain cosmological models and gravity. In particular the matter power spectrum $P(k)$ brings information about the cosmological distance evolution and the galaxy clustering together. However the building of $P(k)$ from galaxy catalogues needs a cosmological model to convert angles on the sky and redshifts into distances, which leads to difficulties when comparing data with predicted $P(k)$ from other cosmological models, and for photometric surveys like LSST. The angular power spectrum $C_\ell(z_1,z_2)$ between two bins located at redshift $z_1$ and $z_2$ contains the same information than the matter power spectrum, is free from any cosmological assumption, but the prediction of $C_\ell(z_1,z_2)$ from $P(k)$ is a costly computation when performed exactly. The Angpow software aims at computing quickly and accurately the auto ($z_1=z_2$) and cross ($z_1 \neq z_2$) angular power spectra between redshift bins. We describe the developed algorithm, based on developments on the Chebyshev polynomial basis and on the Clenshaw-Curtis quadrature method. We validate the results with other codes, and benchmark the performance. Angpow is flexible and can handle any user defined power spectra, transfer functions, and redshift selection windows. The code is fast enough to be embedded inside programs exploring large cosmological parameter spaces through the $C_\ell(z_1,z_2)$ comparison with data. We emphasize that the Limber's approximation, often used to fasten the computation, gives wrong $C_\ell$ values for cross-correlations.Comment: Published in Astronomy & Astrophysic

A direct method to compute the galaxy count angular correlation function including redshift-space distortions

In the near future, cosmology will enter the wide and deep galaxy survey area allowing high-precision studies of the large scale structure of the universe in three dimensions. To test cosmological models and determine their parameters accurately, it is natural to confront data with exact theoretical expectations expressed in the observational parameter space (angles and redshift). The data-driven galaxy number count fluctuations on redshift shells, can be used to build correlation functions $C(\theta; z_1, z_2)$ on and between shells which can probe the baryonic acoustic oscillations, the distance-redshift distortions as well as gravitational lensing and other relativistic effects. Transforming the model to the data space usually requires the computation of the angular power spectrum $C_\ell(z_1, z_2)$ but this appears as an artificial and inefficient step plagued by apodization issues. In this article we show that it is not necessary and present a compact expression for $C(\theta; z_1, z_2)$ that includes directly the leading density and redshift space distortions terms from the full linear theory. It can be evaluated using a fast integration method based on Clenshaw-Curtis quadrature and Chebyshev polynomial series. This new method to compute the correlation functions without any Limber approximation, allows us to produce and discuss maps of the correlation function directly in the observable space and is a significant step towards disentangling the data from the tested models

Campagne Kilkenny A La Carte Menu 2017

Campagne restaurant in Kilkenny city opened in 2008. The emphasis has been to serve food based on high-quality seasonal produce with French influences in a relaxed and comfortable dining area. Located under the old railway arches on Gas House Lane, Campagne boasts a stylish interior featuring oak flooring, curved banquette leather seating and modern paintings depicting rural life by kilkenny artist Catherine Barron. Campagne has been awarded many prestigious awards on a national and international level, most notably one Michelin star status in September 2013.https://arrow.tudublin.ie/menus21c/1321/thumbnail.jp

Campagne Kilkenny Dessert Menu 2017

Campagne restaurant in Kilkenny city opened in 2008. The emphasis has been to serve food based on high-quality seasonal produce with French influences in a relaxed and comfortable dining area. Located under the old railway arches on Gas House Lane, Campagne boasts a stylish interior featuring oak flooring, curved banquette leather seating and modern paintings depicting rural life by kilkenny artist Catherine Barron. Campagne has been awarded many prestigious awards on a national and international level, most notably one Michelin star status in September 2013.https://arrow.tudublin.ie/menus21c/1322/thumbnail.jp

Comparison of the CERN-MEMPHYS and T2HK neutrino oscillation experiments

In this talk I compare the physics potential of possible future neutrino oscillation experiments from CERN to a Mt scale water Cerenkov detector at Frejus (MEMPHYS) and of the T2HK proposal in Japan, where for the CERN experiments an SPL Superbeam and a $\gamma=100$ Beta Beam are considered.Comment: Talk given at NOW 2006, 9-16 Sep 2006, Conca Specchiulla, Otranto, Italy, 3 pages, 2 figure

Campagne Kilkenny Group Menu 2017

Campagne restaurant in Kilkenny city opened in 2008. The emphasis has been to serve food based on high-quality seasonal produce with French influences in a relaxed and comfortable dining area. Located under the old railway arches on Gas House Lane, Campagne boasts a stylish interior featuring oak flooring, curved banquette leather seating and modern paintings depicting rural life by kilkenny artist Catherine Barron. Campagne has been awarded many prestigious awards on a national and international level, most notably one Michelin star status in September 2013.https://arrow.tudublin.ie/menus21c/1323/thumbnail.jp

Campagne Kilkenny Lunch and Early Bird Menu 2017

Campagne restaurant in Kilkenny city opened in 2008. The emphasis has been to serve food based on high-quality seasonal produce with French influences in a relaxed and comfortable dining area. Located under the old railway arches on Gas House Lane, Campagne boasts a stylish interior featuring oak flooring, curved banquette leather seating and modern paintings depicting rural life by kilkenny artist Catherine Barron. Campagne has been awarded many prestigious awards on a national and international level, most notably one Michelin star status in September 2013.https://arrow.tudublin.ie/menus21c/1324/thumbnail.jp

Physics potential of the CERN-MEMPHYS neutrino oscillation project

We consider the physics potential of CERN based neutrino oscillation experiments consisting of a Beta Beam (BB) and a Super Beam (SPL) sending neutrinos to MEMPHYS, a 440 kt water \v{C}erenkov detector at Frejus, at a distance of 130 km from CERN. The $\theta_{13}$ discovery reach and the sensitivity to CP violation are investigated, including a detailed discussion of parameter degeneracies and systematical errors. For SPL sensitivities similar to the ones of the phase II of the T2K experiment (T2HK) are obtained, whereas the BB may reach significantly better sensitivities, depending on the achieved number of total ion decays. The results for the CERN-MEMPHYS experiments are less affected by systematical uncertainties than T2HK. We point out that by a combination of data from BB and SPL a measurement with antineutrinos is not necessary and hence the same physics results can be obtained within about half of the measurement time compared to one single experiment. Furthermore, it is shown how including data from atmospheric neutrinos in the MEMPHYS detector allows to resolve parameter degeneracies and, in particular, provides sensitivity to the neutrino mass hierarchy and the octant of $\theta_{23}$.Comment: 32 pages, 17 figures, minor improvements on the text wrt to v2, version to appear in JHE

What is the probability that θ13\theta_{13} and CP violation will be discovered in future neutrino oscillation experiments?

The sensitivity of future neutrino oscillation experiments is determined within a frequentist framework by using a statistical procedure based on Monte Carlo simulations. I consider the search for a non-zero value of the mixing angle $\theta_{13}$ at the T2K and Double-Chooz experiments, as well as the discovery of CP violation at the example of the T2HK experiment. The probability that a discovery will be made at a given confidence level is calculated as a function of the true parameter values by generating large ensembles of artificial experiments. The interpretation of the commonly used sensitivity limits is clarified.Comment: 11 pages, 5 figure

Disentangling inertial waves from eddy turbulence in a forced rotating turbulence experiment

We present a spatio-temporal analysis of a statistically stationary rotating turbulence experiment, aiming to extract a signature of inertial waves, and to determine the scales and frequencies at which they can be detected. The analysis uses two-point spatial correlations of the temporal Fourier transform of velocity fields obtained from time-resolved stereoscopic particle image velocimetry measurements in the rotating frame. We quantify the degree of anisotropy of turbulence as a function of frequency and spatial scale. We show that this space-time-dependent anisotropy is well described by the dispersion relation of linear inertial waves at large scale, while smaller scales are dominated by the sweeping of the waves by fluid motion at larger scales. This sweeping effect is mostly due to the low-frequency quasi-two-dimensional component of the turbulent flow, a prominent feature of our experiment which is not accounted for by wave turbulence theory. These results question the relevance of this theory for rotating turbulence at the moderate Rossby numbers accessible in laboratory experiments, which are relevant to most geophysical and astrophysical flows