Elena Giusarma

Cosmic Dark Radiation and Neutrinos

New measurements of the cosmic microwave background (CMB) by the Planck mission have greatly increased our knowledge about the universe. Dark radiation, a weakly interacting component of radiation, is one of the important ingredients in our cosmological model which is testable by Planck and other observational probes. At the moment, the possible existence of dark radiation is an unsolved question. For instance, the discrepancy between the value of the Hubble constant, , inferred from the Planck data and local measurements of can to some extent be alleviated by enlarging the minimal CDM model to include additional relativistic degrees of freedom. From a fundamental physics point of view, dark radiation is no less interesting. Indeed, it could well be one of the most accessible windows to physics beyond the standard model, for example, sterile neutrinos. Here, we review the most recent cosmological results including a complete investigation of the dark radiation sector in order to provide an overview of models that are still compatible with new cosmological observations. Furthermore, we update the cosmological constraints on neutrino physics and dark radiation properties focusing on tensions between data sets and degeneracies among parameters that can degrade our information or mimic the existence of extra species.

Constraints on neutrino masses from Planck and Galaxy clustering data

We present here bounds on neutrino masses from the combination of recent Planck cosmic microwave background (CMB) measurements and galaxy clustering information from the Baryon Oscillation Spectroscopic Survey, part of the Sloan Digital Sky Survey-III. We use the full shape of either the photometric angular clustering (Data Release 8) or the 3D spectroscopic clustering (Data Release 9) power spectrum in different cosmological scenarios. In the ΛCDM scenario, spectroscopic galaxy clustering measurements improve significantly the existing neutrino mass bounds from Planck data. We find ∑ m_ν < 0.39  eV at 95% confidence level for the combination of the 3D power spectrum with Planck CMB data (wi lensing included) and Wilkinson Microwave Anisoptropy Probe 9-year polarization measurements. Therefore, robust neutrino mass constraints can be obtained without the addition of the prior on the Hubble constant from Hubble Space Telescope. In extended cosmological scenarios with a dark energy fluid or with nonflat geometries, galaxy clustering measurements are essential to pin down the neutrino mass bounds, providing in the majority of cases better results than those obtained from the associated measurement of the baryon acoustic oscillation scale only. In the presence of a freely varying (constant) dark energy equation of state, we find ∑ m_ν < 0.49  eV at 95% confidence level for the combination of the 3D power spectrum with Planck CMB data (with lensing included) and Wilkinson Microwave Anisoptropy Probe 9-year polarization measurements. This same data combination in nonflat geometries provides the neutrino mass bound ∑ m_ν < 0.35  eV at 95% confidence level.

Dark Radiation and Inflationary Freedom after Planck 2015

The simplest inflationary models predict a primordial power spectrum (PPS) of the curvature fluctuations that can be described by a power-law function that is nearly scale invariant. It has been sh ...

Impact of general reionization scenarios on extraction of inflationary parameters

We would like to thank William Kinney for useful discussion. O. M.s work is supported by the MICINN (Spain) Ramon y Cajal Contract Nos. AYA2008-03531 and CSD2007-00060. M. P. is supported by a MEC-FPU Spanish grant.

Robustness of cosmological axion mass limits

Eleonora Di Valentino, 2 Stefano Gariazzo, 4 Elena Giusarma, and Olga Mena CNRS, UMR 7095, Institut d’Astrophysique de Paris, F-75014, Paris, France Sorbonne Universites, Institut Lagrange de Paris (ILP), F-75014, Paris, France Department of Physics, University of Torino, Via P. Giuria 1, I–10125 Torino, Italy INFN, Sezione di Torino, Via P. Giuria 1, I–10125 Torino, Italy Physics Department and INFN, Universita di Roma “La Sapienza”, Ple Aldo Moro 2, 00185, Rome, Italy IFIC, Universidad de Valencia-CSIC, 46071, Valencia, Spain

N-body simulations of gravitational redshifts and other relativistic distortions of galaxy clustering

Large redshift surveys of galaxies and clusters are providing the first opportunities to search for distortions in the observed pattern of large-scale structure due to such effects as gravitational redshift. We focus on non-linear scales and apply a quasi-Newtonian approach using N-body simulations to predict the small asymmetries in the cross-correlation function of two galaxy different populations. Following recent work by Bonvin et al., Zhao and Peacock and Kaiser on galaxy clusters, we include effects which enter at the same order as gravitational redshift: the transverse Doppler effect, light-cone effects, relativistic beaming, luminosity distance perturbation and wide-angle effects. We find that all these effects cause asymmetries in the cross-correlation functions. Quantifying these asymmetries, we find that the total effect is dominated by the gravitational redshift and luminosity distance perturbation at small and large scales, respectively. By adding additional subresolution modelling of galaxy structure to the large-scale structure information, we find that the signal is significantly increased, indicating that structure on the smallest scales is important and should be included. We report on comparison of our simulation results with measurements from the SDSS/BOSS galaxy redshift survey in a companion paper.

Current status of modified gravity

We revisit the cosmological viability of the Hu

Relativistic effects on galaxy redshift samples due to target selection

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Harrison-Zel'dovich primordial spectrum is consistent with observations

Sawicki modified gravity scenario. The impact of such a modification on the different cosmological observables, including gravitational waves, is carefully described. The most recent cosmological data, as well as constraints on the relationship between the clustering parameter

Gravitational Lensing of CMB by Quasars in SDSS-IV

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