CIB-Galaxy Cross-Correlation

The cosmic infrared background (CIB) is the integrated emission from all dusty star-forming galaxies across cosmic history, redshifted into the far-infrared and submillimeter. Cross-correlating the CIB with galaxy surveys and CMB lensing maps probes the large-scale distribution of star formation as a function of cosmic time and environment. Several analyses have found that the CIB-galaxy cross-correlation amplitude and angular scale dependence deviate modestly from ΛCDM predictions: the correlation is stronger on large angular scales than expected from the standard halo model of galaxy clustering, and the redshift kernel of the CIB appears to extend to higher redshifts than current galaxy formation models predict, implying more star formation at z > 3 than ΛCDM accommodates. The cross-correlation with CMB lensing also shows an excess consistent with more large-scale structure at intermediate redshifts than expected.

Successive Collision Theory explains the excess CIB-galaxy cross-correlation through pre-existing stellar populations and the angular momentum inheritance mechanism. In SCT, star formation did not begin from scratch at z ~ 10–20 as hierarchical assembly models predict; the colliding pockets contained prior stellar generations whose evolved products — including dust-enriched circumgalactic and intergalactic gas — were thermalized and incorporated into the post-collision debris. The effective star formation rate at high redshift is therefore augmented by the residual star formation activity in thermalized pre-existing material, producing a CIB redshift kernel that extends to higher redshifts and contributes more large-scale power than the ΛCDM star-formation history predicts. The large-angular-scale excess in the CIB-galaxy correlation reflects the coherent organization of star formation along the angular momentum strata of the collision debris, which produces larger correlation lengths than stochastic hierarchical assembly.

The gravitational superposition from overlapping nested comoving frames enhances the effective gravitational clustering of infrared-bright galaxies on large scales, boosting the CIB angular power spectrum on scales comparable to the frame hierarchy's characteristic sizes. This superposition effect increases the CIB-CMB lensing cross-correlation on degree angular scales — precisely where the observed excess lies — without requiring additional dark matter or modified gravity. SCT therefore predicts that the CIB excess is correlated with the lensing amplitude excess A_lens > 1 measured in the CMB power spectrum, both being manifestations of the same gravitational superposition mechanism. The cross-correlation of CIB maps with galaxy density fields in different large-scale structure environments should reveal stronger correlations in denser regions where the frame superposition depth is greatest.