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Francesco De Bernardis

Publications and source records attributed to Francesco De Bernardis.

21 records · Page 2Linked to original sources

An improved limit on the neutrino mass with CMB and redshift-dependent halo bias-mass relations from SDSS, DEEP2, and Lyman-Break Galaxies

We use measurements of luminosity-dependent galaxy bias at several different redshifts, SDSS at $z=0.05$, DEEP2 at $z=1$ and LBGs at $z=3.8$, combined with WMAP five-year cosmic microwave background anisotropy data and SDSS Red Luminous Galaxy survey three-dimensional clustering power spectrum to put constraints on cosmological parameters. Fitting this combined dataset, we show that the luminosity-dependent bias data that probe the relation between halo bias and halo mass and its redshift evolution are very sensitive to sum of the neutrino masses: in particular we obtain the upper limit of $\sum m_ν<0.28$eV at the 95% confidence level for a $ΛCDM + m_ν$ model, with a $σ_8$ equal to $σ_8=0.759\pm0.025$ (1$σ$). When we allow the dark energy equation of state parameter $w$ to vary we find $w=-1.30\pm0.19$ for a general $wCDM+m_ν$ model with the 95% confidence level upper limit on the neutrino masses at $\sum m_ν<0.59$eV. The constraint on the dark energy equation of state further improves to $w=-1.125\pm0.092$ when using also ACBAR and supernovae Union data, in addition to above, with a prior on the Hubble constant from the Hubble Space Telescope.

astro-ph↗

Anisotropies in the Cosmic Neutrino Background after WMAP 5-year Data

We search for the presence of cosmological neutrino background (CNB) anisotropies in recent WMAP 5-year data using their signature imprinted on modifications to cosmic microwave background (CMB) anisotropy power spectrum. By parametrizing the neutrino background anisotropies with the speed viscosity parameter $c_\vis$, we find that the WMAP 5-year data alone provide only a weak indication for CNB anisotropies with $c_\vis^2 > 0.06$ at the 95% confidence level. When we combine CMB anisotropy data with measurements of galaxy clustering, SN-Ia Hubble diagram, and other cosmological information, the detection increases to $c_\vis^2 > 0.16$ at the same 95% confidence level. Future data from Planck, combined with a weak lensing survey such as the one expected with DUNE from space, will be able to measure the CNB anisotropy parameter at about 10% accuracy. We discuss the degeneracy between neutrino background ansiotropies and other cosmological para meters such as the number of effective neutrinos species and the dark energy equation of state.

astro-ph↗

Constraints on Distance Duality Relation from Sunyaev Zel'dovich Effect and Chandra X-ray measurements

We demonstrate that the recent measurements of the angular diameter distance of 38 cluster of galaxies using Chandra X-ray data and radio observations from the OVRO and BIMA interferometric arrays place new and independent constraints on deviations in the duality relation between angular and luminosity distances. Using only cluster data, we found that the ratio between the two distances defined as $η= D_L/D_A(1+z)^2.$ is bound to be $η=0.97\pm0.03$ at 68% c.l. with no evidence for distance duality violation. Comparing the cluster angular diameter distance data with luminosity distance data from type Ia Supernovae, we obtain the model independent constraint $η=1.01\pm0.07$ at 68% c.l.. Those results provide an useful check for the cosmological concordance model and for the presence of systematics in SN-Ia and clusters data.

gr-qc↗