Cosmology and source redshift distributions from combining radio weak lensing with CMB lensing

Kalaja, A., Harrison, I. ORCID: https://orcid.org/0000-0002-4437-0770 and Coulton, William R. 2025. Cosmology and source redshift distributions from combining radio weak lensing with CMB lensing. Journal of Cosmology and Astroparticle Physics 2025 (07) , 001. 10.1088/1475-7516/2025/07/001

PDF - Published Version Download (2MB)

Abstract

Measurements of weak gravitational lensing using the cosmic microwave background and the shapes of galaxies have refined our understanding of the late-time history of the Universe. While optical surveys have been the primary source for cosmic shear measurements, radio continuum surveys offer a promising avenue. Relevant radio sources, principally star-forming galaxies, have populations with higher mean redshifts and are less affected by dust extinction compared to optical sources. We focus on the future mid frequency SKA radio telescope and explore the cross-correlation between radio cosmic shear and CMB lensing convergence (γR × κ CMB). We investigate its potential in constraining the redshift distribution of radio galaxy samples and improving cosmological parameter constraints, including the neutrino sector. Using simulations of the first phase of the SKA and the Simons Observatory as a CMB experiment, we show how this γR × κ CMB cross-correlation can provide ∼ 1 - 10% calibration of the overall radio source redshift distribution, which in turn can significantly tighten otherwise degenerate measurements of radio galaxy bias. For the case of the next-generation full SKA, we find that the full combination of auto- and cross-spectra between γR and κ CMB becomes more powerful than the equivalent case using γO from a Euclid-like survey, with constraints 30% tighter on ΛCDM parameters and narrower bounds on sum of neutrino masses at the level of ∼ 24%. These constraints are also driven by higher redshifts and larger scales than other galaxy-CMB cross-correlations, potentially shedding light on different physical models. Our findings demonstrate the potential of radio weak lensing in improving constraints, and establish the groundwork for future joint analyses of CMB experiments and radio continuum surveys.

Item Type:	Article
Date Type:	Published Online
Status:	Published
Schools:	Schools > Physics and Astronomy
Additional Information:	License information from Publisher: LICENSE 1: URL: http://creativecommons.org/licenses/by/4.0/, Type: cc-by
Publisher:	IOP Publishing
Date of First Compliant Deposit:	8 July 2025
Date of Acceptance:	13 May 2025
Last Modified:	08 Jul 2025 09:30
URI:	https://orca.cardiff.ac.uk/id/eprint/179624

Actions (repository staff only)

Edit Item