Measuring the evolution of intergalactic gas from z=0 to 5 using the kinematic Sunyaev-Zel'dovich effect

TL;DR

This paper introduces ARF-kSZ tomography, a new method to measure the distribution of intergalactic gas from redshift 0 to 5, revealing it contains half of cosmic baryons outside dark matter haloes.

Contribution

The study develops and applies ARF-kSZ tomography to detect and characterize intergalactic gas across a wide redshift range, providing a nearly complete baryon census.

Findings

Detected kSZ effect with 11 sigma significance across multiple tracers.

Found intergalactic gas outside dark matter haloes with densities 10-250 times cosmic average.

Concluded that this gas accounts for half of cosmic baryons.

Abstract

A complete census of baryons in the late universe is a long-standing challenge due to the intermediate temperate and rarefied character of the majority of cosmic gas. To gain insight into this problem, we extract measurements of the kinematic Sunyaev-Zel'dovich (kSZ) effect from the cross-correlation of angular redshift fluctuations maps, which contain precise information about the cosmic density and velocity fields, and CMB maps high-pass filtered using aperture photometry; we refer to this technique as ARF-kSZ tomography. Remarkably, we detect significant cross-correlation for a wide range of redshifts and filter apertures using 6dF galaxies, BOSS galaxies, and SDSS quasars as tracers, yielding a 11 sigma detection of the kSZ effect. We then leverage these measurements to set constraints on the location, density, and abundance of gas inducing the kSZ effect, finding that this gas resides outside dark matter haloes, presents densities ranging from 10 to 250 times the cosmic average, and comprises half of cosmic baryons. Taken together, these findings indicate that ARF-kSZ tomography provides a nearly complete census of intergalactic gas from z=0 to 5.