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Combinations of cosmic microwave background and large-scale structure cosmological probes

Abstract : This thesis addresses the combinations of cosmological probes from the measurements of the cosmic microwave background (CMB) and galaxy redshift surveys, and exploits data from the Planck satellite and the Baryon Oscillation Spectroscopic Survey (BOSS) of the Sloan Digital Sky Survey. It explores how cross-correlations between different data sets can be used to detect new signals and improve contraints on cosmological parameters. First, we measure, for the first time, the cross-correlation between gravitational lensing of the CMB and the power spectrum of the Lyman-α forest in the spectra of quasars. This effect, which emerges from purely non-linear evolution, is interpreted as the response of the power spectrum to large-scale modes. It shows how fluctuations in the density of neutral hydrogen in the intergalactic medium are affected by large-scale fluctuations in the density of dark matter. The measured signal is compatible with the theoretical approach and simulations run by another group. In a second time, we develop a formalism enabling the joint analysis of the galaxy/quasar density contrast and CMB lensing. Taking cross-correlations between these probes into account reduces error bars on some cosmological parameters by up to 20%, equivalent to an increase in the size of the survey of about 50%. This analysis is completed by CMB temperature anisotropies information in order to constrain all the parameters of the ΛCDM standard model and galaxy biases at once. Finally, it is extended to obtain contraints on the dark energy equation of state as well as the sum of the masses of neutrinos
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Submitted on : Sunday, May 19, 2019 - 11:45:10 AM
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  • HAL Id : tel-01829118, version 2

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Cyrille Doux. Combinations of cosmic microwave background and large-scale structure cosmological probes. Physics [physics]. Université Sorbonne Paris Cité, 2017. English. ⟨NNT : 2017USPCC230⟩. ⟨tel-01829118v2⟩

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