2025/03/31 by Noah Sailer, Joseph DeRose, Sailer, Noah +13 · 4 citations
Physics and Astronomy · #Astronomy and Astrophysical Research #Cosmology and Gravitation Theories #Cosmology and Nongalactic Astrophysics (astro-ph.CO) #FOS: Physical sciences #Galaxies: Formation, Evolution, Phenomena
paper · pdf · doi:10.48550/arxiv.2503.24385
openalex publication_date 2025/03/31 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
We use a Hybrid Effective Field Theory (HEFT) model to constrain the evolution of low-redshift (z\lesssim0.4) matter fluctuations by cross-correlating DESI Bright Galaxy Survey (BGS) legacy imaging with the latest CMB lensing maps from Planck and ACT. Our tomographic BGS analysis finds that the evolution and amplitude of matter fluctuations align with CMB-conditioned ΛCDM predictions. When including DESI Baryon Acoustic Oscillation (BAO) measurements we obtain σ8 = 0.876+0.051-0.067 from BGS alone. Jointly analyzing BGS and Luminous Red Galaxy (LRG) cross-correlations with the same CMB lensing maps yields σ8 = 0.791±0.021. As a complementary approach we isolate the galaxy magnification signal from the cross-correlation of non-overlapping BGS and LRG photometric redshift bins, ruling out the null-magnification hypothesis at 11σ. For the first time, we constrain structure growth from the (finite-difference calibrated) galaxy magnification signal and find σ8=0.720±0.047 (\rm stat.)±0.050 (\rm sys.) when adopting a linear bias model and including BAO data.