The Baryon Content of Cosmic Structures

TL;DR

This paper inventories baryonic and gravitating mass across cosmic structures, revealing how baryon conversion to stars varies with mass and highlighting the missing baryons in smaller galaxies.

Contribution

It provides a comprehensive analysis of baryon content from small galaxies to clusters, identifying the efficiency peak and the extent of baryon detection.

Findings

Star formation efficiency peaks in bright group galaxies.

Most baryons are detected in large clusters, fewer in dwarf galaxies.

Significant baryons are missing in small galaxies.

Abstract

We make an inventory of the baryonic and gravitating mass in structures ranging from the smallest galaxies to rich clusters of galaxies. We find that the fraction of baryons converted to stars reaches a maximum between M500 = 1E12 and 1E13 Msun, suggesting that star formation is most efficient in bright galaxies in groups. The fraction of baryons detected in all forms deviates monotonically from the cosmic baryon fraction as a function of mass. On the largest scales of clusters, most of the expected baryons are detected, while in the smallest dwarf galaxies, fewer than 1% are detected. Where these missing baryons reside is unclear.