Think Planck ACT: A Cross-Correlation of the CIB and CMB using Planck, ACT and UltraVISTA

Abstract

At small scales (\(l \geq 3000)\), the cosmic microwave background (CMB) foreground is dominated by an unresolved cosmic infrared background (CIB). In this analysis, we present the groundwork to quantify the amount of CIB relative to the CMB using a cross-correlation at frequencies 148 GHz, 353 GHz, and 545 GHz, with data from the Atacama Cosmology Telescope (ACT), and the Planck space observatory. We perform a stacking technique on the UltraVISTA \(K_s\)-selected catalog (\(K_s \sim 23.4\)) and maps at these frequencies to estimate contributions to the CIB from known galaxies and their faint, but physically-associated (and thereby correlated) companions at frequencies never previously resolved. We find that at smaller frequencies, most of the contribution to the CIB comes from less-massive sources (stellar mass log(\(M/M_{\odot}\)) \(= 9-10\)), more contribution comes from high-mass sources (stellar mass log(\(M/M_{\odot}\)) \(\geq 11\)), and sources in the intermediate mass range (stellar mass log(\(M/M_{\odot}\)) \(= 10-11\)) contribute the least at higher frequencies. We also find that the peak contribution to the CIB increases in redshift with smaller frequencies for star-forming galaxies. We also find that at small frequencies, there is a greater contribution from quiescent sources than at higher frequencies -- \(\sim 25\)\% in this study compared to \(\sim 5\)\% from previous studies. We then perform a cross-correlation of the CIB and the CMB in real-space and in Fourier-space, finding higher correlation at higher frequencies where the CIB dominates. We also find that correlation between the CIB and the CMB increases with increasing redshift and stellar-mass, and that the majority of the correlation comes from star-forming sources. We also present estimates for the scales to which we can extend our investigations of the CMB based on its fraction of correlated signal with the CIB, and applications of this method.