Retrieving cosmological information from small-scale CMB foregrounds II. The kinetic Sunyaev Zel'dovich effect

• Main Authors: Gorce, Adélie, Douspis, Marian, Salvati, Laura
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: arXiv 2022
• Subjects: Cosmology and Nongalactic Astrophysics astro-ph.CO; FOS Physical sciences; South Pole; South pole
• Online Access: https://dx.doi.org/10.48550/arxiv.2202.08698; https://arxiv.org/abs/2202.08698

Recent results of ground-based telescopes, giving high-quality measurements of the CMB temperature power spectrum on small scales motivate the need for an accurate model of foregrounds, which dominate the primary signal at these multipoles. In a previous work, we have shown that cosmological information could be retrieved from the power spectrum of the thermal Sunyaev Zel'dovich (SZ) effect. In this work, we introduce a physically-motivated model of the Epoch of Reionisation (EoR) in the cosmological analysis of CMB data, coherent on all scales. In particular, at high multipoles, the power spectrum of the kinetic SZ (kSZ) effect is inferred from a set of cosmological parameters by a machine-learning algorithm. First including an asymmetric parameterisation of the EoR history in the Planck 2018 data analysis, we retrieve a value of the CMB optical depth consistent with previous results but giving a completely different history of the high-redshift Universe, in which the first luminous sources light up as early as $z=15$. Considering the latest small-scale data from the South Pole Telescope (SPT) and letting the cosmology free to vary, we find that including the new cosmology-dependent tSZ and kSZ spectra help tighten the constraints on the amplitudes of these two spectra by breaking the degeneracy between their amplitudes. We report a $5σ$ measurement of the kSZ signal at $\ell=3000$ ($\mathcal{D}_{3000}^\mathrm{kSZ} = 3.3 \pm 0.7~μ\mathrm{K}^2$, $1σ$), marginalised over cosmology, as well as an upper limit on the patchy signal $\mathcal{D}_{3000}^\mathrm{pkSZ}<1.58~μ\mathrm{K}^2$ (95\% C.L.). Additionally, we find that the SPT data favours slightly earlier reionisation scenarios than Planck, leading to $τ= 0.062 \pm 0.012$ and a reionisation midpoint $z_{\rm re} = 7.9\pm1.1$ ($1σ$), in line with constraints from high-redshift quasars and galaxies. : 17 pages, 13 figures, comments welcome!