Browsing by Author "Finelli, Fabio"

Now showing 1 - 3 of 3
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    Measuring lensing ratios with future cosmological surveys
    (American Physical Society, 2020) Ballardini, Mario; Bermejo-Climent, Jos´e Ramón; Finelli, Fabio
    The ratio between the CMB lensing/galaxy counts and the galaxy shear/galaxy counts cross-correlations combines the information from different cosmological probes to infer cosmographic measurements that are less dependent on astrophysical uncertainties and can constrain the geometry of the Universe. We discuss the future perspectives for the measurement of this lensing ratio as previously introduced, i.e., with the use of the Limber and flat-sky approximations and neglecting all the effects on the galaxy survey from observing on the past light cone. We then show how the cosmological information in this estimator is affected by the Limber approximation and by the inclusion of the redshift space distortions (RSD) and lensing magnification contributions to the galaxy number counts.
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    On the primordial origin of the smoothing excess in the Planck temperature power spectrum in light of LSS data
    (IOP Publishing, 2022) Ballardini, Mario; Finelli, Fabio
    The Planck DR3 measurements of the temperature and polarization anisotropies power spectra of the cosmic microwave background (CMB) show an excess of smoothing of the acoustic peaks with respect to ΛCDM, often quantified by a phenomenological parameter A L. A specific feature superimposed to the primordial power spectrum has been suggested as a physical solution for this smoothing excess. Here, we investigate the impact of this specific localized oscillation with a frequency linear in the wavenumber, designed to mimic the smoothing of CMB temperature spectrum corresponding to A L ≃ 1.1-1.2 on the matter power spectrum.
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    Scalar-tensor theories of gravity, neutrino physics, and the H0 tension
    (IOP Publishing, 2020) Ballardini, Mario; Braglia, Matteo; Finelli, Fabio
    We use Planck 2018 data to constrain the simplest models of scalar-tensor theories characterized by a coupling to the Ricci scalar of the type F(σ)R with F(σ) = N2 pl + ξσ2 . We update our results with previous Planck and BAO data releases obtaining the tightest constraints to date on the coupling parameters, that is ξ < 5.5 × 10−4 for Npl = 0 (induced gravity or equivalently extended Jordan-Brans-Dicke) and (Npl √ 8πG) − 1 < 1.8 × 10−5 for ξ = −1/6 (conformal coupling), both at 95% CL. Because of a modified expansion history after radiation-matter equality compared to the ΛCDM model, all these dynamical models accommodate a higher value for H0 and therefore alleviate the tension between Planck/BAO and distance-ladder measurement from SNe Ia data from 4.4σ at best to 2.7-3.2σ with CMB alone and 3.5-3.6σ including BAO data.