We use a hybrid effective field theory (HEFT) model to constrain the evolution of low-redshift ($z\lesssim 0.4$) matter fluctuations by cross-correlating DESI Bright Galaxy Survey (BGS) legacy imaging with the latest cosmic microwave background (CMB) lensing maps from Planck and Atacama cosmology telescope. Our tomographic BGS analysis finds that the evolution and amplitude of matter fluctuations align with CMB-conditioned $\mathrm{\Lambda }$ cold dark matter predictions. When including DESI baryon acoustic oscillation (BAO) measurements we obtain ${\sigma }_8={0.876}_{-0.067}^{+0.051}$ from BGS alone. Jointly analyzing BGS and luminous red galaxy (LRG) cross-correlations with the same CMB lensing maps yields ${\sigma }_8=0.791\pm 0.021$. As a complementary approach we isolate the galaxy magnification signal from the cross-correlation of nonoverlapping BGS and LRG photometric redshift bins, ruling out the null-magnification hypothesis at $11\sigma$. For the first time, we constrain quasilinear structure growth from the (finite-difference calibrated) galaxy magnification signal and find ${\sigma }_8=0.720\pm 0.047(\mathrm{stat})\pm 0.050(\mathrm{sys})$ assuming a linear bias model and including BAO data.

Close

PrevNext

View figure in article

• Cosmic microwave background
• Cosmological parameters
• Dark energy
• Dark matter
• Large scale structure of the Universe