Cosmological Parameter Constraints from CMB Lensing with Cosmic Voids

Teeraparb Chantavat, Utane Sawangwit, P. M. Sutter, Benjamin D. Wandelt

Published 2014-09-11Version 1

We investigate the potential of using cosmic voids to constrain cosmological parameters through gravitational lensing of the cosmic microwave background (CMB) and make predictions for the next generation surveys. By assuming the detection of a series of $\approx 10$ voids of size $R_V \gtrsim 20$ Mpc $h^{-1}$ along a line of sight with $\approx$100 -- 200 independent square-degree patches of the sky, we could potentially get constraints of cosmological parameter that are competitive with PLANCK alone. The chance of finding such patches are seemingly small but given the fact that voids occupy the vast majority of volume of the universe, finding a few of those patches and combining them to get constraints on cosmological parameters is possible. This analysis is based on our current knowledge of the average void profile and analytical estimates of the void number function in upcoming surveys. The full potential of this technique relies on an accurate determination of the void profile to $\approx 10$ percent level. CMB lensing with voids will provide a competitive and complimentary route to parameter constraints for the next generation cosmological observations. For example, we predict that for a EUCLID-like mission the constraints are $100\omega_b = 2.26 \pm 0.05,\ \omega_c = 0.114 \pm 0.004,\ \Omega_\Lambda = 0.684 \pm 0.014,\ \Delta_{\mathcal{R}}^2 = (2.40 \pm 11.05) \times 10^{-9},\ n_s = 0.971 \pm 0.026,\ \tau = 0.0851 \pm 2.4947$ for our conservative prediction with 100 square-degree patches.