http://arxiv.org/abs/1905.12000
The Cosmic Microwave Background (CMB) yields an inference on the matter sound horizon, within the Standard Model. Independent, direct measurements of the sound horizon are then a probe of possible deviations from the Standard Model. We aim at measuring the sound horizon $r_s$ from low-redshift indicators, completely independent from CMB inference. We use the measured product $H(z)r_s$ from Baryon Acoustic Oscillations (BAO), plus Supernovae~\textsc{I}a to constrain $H(z)/H_{0}$ and time-delay lenses analysed by the H0LiCOW collaboration to anchor cosmological distances ($\propto H_{0}^{-1}$). Additionally, we investigate the influence of adding a sample of higher-redshift quasars with standardisable UV-Xray luminosity distances. We adopt polynomial expansions in $H(z)$ or in comoving distances, so that our inference is completely independent of any underlying cosmological model. Our measurements are independent of Cepheids and systematics from peculiar motions, to within percent-level accuracy. The inferred sound horizon $r_s$ varies between $(133 \pm 8)$~Mpc and $(138 \pm 5)$~Mpc across different models. The discrepancy with CMB measurements is robust against model choice. Statistical uncertainties are comparable to systematics. The combination of time-delay lenses, supernovae and BAO yields a cosmology-independent (and Cepheid-calibration-independent) distance ladder, and a CMB-independent measurement of $r_s.$ These cosmographic measurements are then a competitive test of the Standard Model, regardless of hypotheses on the underlying cosmology.
N. Arendse, A. Agnello and R. Wojtak
Thu, 30 May 19
47/57
Comments: A&A subm. 28/05/2019, 6 pages, 3 figures
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