Euclid: Forecasts from the void-lensing cross-correlation

Abstract

The Euclid space telescope will survey a large dataset of cosmic voids traced by dense samples of galaxies. In this work we estimate its expected performance when exploiting angular photometric void clustering, galaxy weak lensing, and their cross-correlation. To this aim, we implemented a Fisher matrix approach tailored for voids from the Euclid photometric dataset and we present the first forecasts on cosmological parameters that include the void-lensing correlation. We examined two different probe settings, pessimistic and optimistic, both for void clustering and galaxy lensing. We carried out forecast analyses in four model cosmologies, accounting for a varying total neutrino mass, M ν , and a dynamical dark energy (DE) equation of state, w(z), described by the popular Chevallier-Polarski-Linder parametrization. We find that void clustering constraints on h and Ω b are competitive with galaxy lensing alone, while errors on n s decrease thanks to the orthogonality of the two probes in the 2D-projected parameter space. We also note that, as a whole, with respect to assuming the two probes as independent, the inclusion of the void-lensing crosscorrelation signal improves parameter constraints by 10 − 15%, and enhances the joint void clustering and galaxy lensing figure of merit (FoM) by 10% and 25%, in the pessimistic and optimistic scenarios, respectively. Finally, when further combining with the spectroscopic galaxy clustering, assumed as an independent probe, we find that, in the most competitive case, the FoM increases by a factor of 4 with respect to the combination of weak lensing and spectroscopic galaxy clustering taken as independent probes. The forecasts presented in this work show that photometric void clustering and its cross-correlation with galaxy lensing deserve to be exploited in the data analysis of the Euclid galaxy survey and promise to improve its constraining power, especially on h, Ω b , the neutrino mass, and the DE evolution.

Why cosmic voids matter: nonlinear structure & linear dynamics

“…This opens up a vast observational window to conduct cosmological experiments, allowing us to make use of voids ranging from a few (or possibly less) to hundreds of Mpc in diameter. As linear dynamics holds up in all voids irrespective of their size, void catalogs can not only be extended via enlarging survey volumes towards higher redshifts (as planned for a number of next-generation surveys, such as Euclid [108,130,131]), but also by conducting deeper observations that provide denser tracer samples and hence smaller sub-voids (e.g., as planned for Roman [132] and 4MOST [133]), even at low redshift. This would open up the possibility to maximize the number of observable linear modes of the density field of large-scale structure that can be exploited for the purpose of cosmological inference, for example via the Alcock-Paczynski effect and RSD [60,66,108], far beyond the previously imposed limits.…”

Cosmological Constraints from the BOSS DR12 Void Size Function

“…We focus in particular on the cosmological degeneracies acting on the parameter planes Ω m -σ 8 , for the ΛCDM model, and Ω m -w, for the wCDM model. This selection is motivated by recent promising studies concerning the complementarity of different void statistics with standard cosmological probes, which showed the effectiveness of a joint analysis in constraining the growth of cosmic structures and the dark energy equation of state (Pisani et al 2015a;Bayer et al 2021;Bonici et al 2022;Contarini et al 2022;Hamaus et al 2022;Kreisch et al 2022;Pelliciari et al 2023).…”

“…It has been exploited for cosmological purposes by means of modeling the geometric and dynamic effects on the average void shape (Lavaux & Wandelt 2012;Pisani et al 2014;Cai et al 2016;Hamaus et al 2016Hamaus et al , 2017Hamaus et al , 2020Hamaus et al , 2022Hawken et al 2017Hawken et al , 2020Achitouv 2019;Correa et al 2019;Aubert et al 2022;Nadathur et al 2020Nadathur et al , 2022Correa et al 2022;Woodfinden et al 2022). Other notable and modern void analyses concern the weak lensing phenomenon (Clampitt & Jain 2015;Chantavat et al 2016Chantavat et al , 2017Gruen et al 2016;Cai et al 2017;Sánchez et al 2017b;Baker et al 2018;Brouwer et al 2018;Fang et al 2019;Davies et al 2021;Vielzeuf et al 2021;Bonici et al 2022), as well as the void autocorrelation function (Chan et al 2014;Hamaus et al 2014aHamaus et al , 2014cClampitt et al 2016;Chuang et al 2017;Kreisch et al 2019;Voivodic et al 2020), and the impact from voids on the integrated Sachs-Wolfe effect in the cosmic microwave background (Granett et al 2008;Cai et al 2014Cai et al , 2017K...…”