Cosmic Census: Relative Distributions of Dark Matter, Galaxies and Diffuse Gas

TL;DR

This study uses cross-correlation of galaxy, lensing, and tSZ data from SDSS and Planck to map the distribution of dark matter, gas, and galaxies, revealing biases and informing future experiments.

Contribution

It provides new constraints on the joint distribution of cosmic components and measures the hydrostatic mass bias using halo-based modeling at median redshift 0.53.

Findings

Detected variation in satellite fraction with stellar mass.

Measured the hydrostatic mass bias, $(1-b_h)=0.6\u00b10.05$.

Forecasted improved constraints from future CMB experiments.

Abstract

Galaxies, diffuse gas, and dark matter make up the cosmic web that defines the large-scale structure of the Universe. We constrained the joint distribution of these constituents by cross-correlating galaxy samples binned by stellar mass from the Sloan Digital Sky Survey CMASS catalog with maps of lensing convergence and the thermal Sunyaev-Zeldovich (tSZ) effect from the Planck mission. Fitting a halo-based model to our measured angular power spectra (galaxy-galaxy, galaxy-lensing convergence, and galaxy-tSZ) at a median redshift of $z=0.53$, we detected variation with stellar mass of the galaxy satellite fraction and galaxy spatial distribution within host halos. We find a tSZ-halo hydrostatic mass bias, $b_h$, such that $(1-b_h)=0.6\pm0.05$, with a hint of a larger bias, $b_h$, at the high stellar mass end. The normalization of the galaxy-cosmic microwave background lensing convergence cross-power spectrum shows that galaxies trace the matter distribution without an indication of stochasticity ($A=0.98\pm 0.09$). We forecast that next-generation cosmic microwave background experiments will improve the constraints on the hydrostatic bias by a factor of two and will be able to constrain the small-scale distribution of dark matter, hence informing the theory of feedback processes.