Doppler boosted dust emission and CIB-galaxy cross-correlations: a new probe of cosmology and astrophysics

TL;DR

This paper introduces the Doppler-boosted Cosmic Infrared Background (DB-CIB) as a new cosmological probe derived from galaxy motions, offering a novel way to study the velocity field without certain astrophysical degeneracies.

Contribution

It proposes the DB-CIB as an independent, degenerate-free probe of cosmic velocities and forecasts its detectability with upcoming experiments.

Findings

DB-CIB is detectable in cross-correlation data.

It serves as a new CMB foreground affecting kSZ measurements.

DB-CIB is immune to the kSZ optical depth degeneracy.

Abstract

We identify a new cosmological signal, the Doppler-boosted Cosmic Infrared Background (DB-CIB), arising from the peculiar motion of the galaxies whose thermal dust emission source the cosmic infrared background (CIB). This new observable is an independent probe of the cosmic velocity field, highly analogous to the well-known kinematic Sunyaev-Zel'dovich (kSZ) effect. Interestingly, DB-CIB does not suffer from the 'kSZ optical depth degeneracy', making it immune from the complex astrophysics of galaxy formation. We forecast that the DB-CIB effect is detectable in the cross-correlation of CCAT-Prime and DESI-like experiments. We show that it also acts as a new CMB foreground which can bias future kSZ cross-correlations, if not properly accounted for.