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arXiv · 2203.11045

First measurement of the correlation between cosmic voids and the Lyman-$\alpha$ forest

Corentin Ravoux·Eric Armengaud·Julian Bautista·James Rich·Jean-Marc Le Goff·Nathalie Palanque-Delabrouille·Michael Walther·Christophe Yèche
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Abstract

We report the first detection at a median redshift $z = 2.49$ of large-scale matter flows around cosmic voids. Voids are identified within a tomographic map of large-scale Lyman-$\alpha$ (Ly$\alpha$) transmissions, built from the eBOSS Ly$\alpha$ forest sample in the SDSS Stripe 82 field. We measure the imprint of flows around voids, known as redshift-space distortions (RSD), with a statistical significance of $8\,\sigma$. The observed quadrupole of the void-forest cross-correlation is described by a linear RSD model. The derived RSD parameter of the Ly$\alpha$ forest around voids is $\beta = 1.21 \pm 0.18$. Our model accounts for the tomographic effect induced by the Ly$\alpha$ data being located along parallel quasar lines of sight. This work presents a novel approach to observing the growth of cosmic structures at redshifts currently inaccessible to galaxy surveys.

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Corentin Ravoux, Eric Armengaud, Julian Bautista, James Rich, Jean-Marc Le Goff, Nathalie Palanque-Delabrouille, Michael Walther, Christophe Yèche. 2022-03-21. First measurement of the correlation between cosmic voids and the Lyman-$\alpha$ forest. https://arxiv.org/abs/2203.11045

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