Measurement of the power spectrum turnover scale from the cross-correlation between CMB lensing and Quaia
Year: 2025
Type: article
Abstract: We use the projected clustering of quasars in the Gaia-unWISE quasar catalog, Quaia, and its cross-correlation with CMB lensing data from Planck, to measure the large-scale turnover of the matter power spectrum, associated with the size of the horizon at the epoch of matter-radiation equality. The turnover is detected with a significance of between 2.3 and 3.1 σ , depending on the method used to quantify it. From this measurement, the equality scale is determined at the ∼ 20 % level. Using the turnover scale as a standard ruler alone (suppressing information from the large-scale curvature of the power spectrum), in combination with supernova data through an inverse distance ladder approach, we measure the current expansion rate to be . The addition of information coming from the power spectrum curvature approximately halves the standard ruler uncertainty. Our measurement in combination with calibrated supernovae from Pantheon + and SH0ES constrains the CMB temperature to be , independently of CMB data. Alternatively, assuming the value of from COBE-FIRAS, we can constrain the effective number of relativistic species in the early Universe to be .
Source: The Open Journal of Astrophysics
DOI: 10.33232/001c.136891
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: diamond
Awards: G434337789, G8487722326
OpenAlex ID: W4409519176