The end point of the collapse and relaxation of a protogalaxy is a dark matter halo, inside of which the baryonic gas is in hydrostatic equilibrium at a temperature of typically a few million degrees. 原星系塌缩与松弛的最终点就是黑暗物质晕,里面有处于流体静力平衡的重子气体,一般温度约数百万度。
A baryon is a composite subatomic particle made up of three quarks (as distinct from mesons, which are composed of one quark and one antiquark). Baryons and mesons belong to the hadron family of particles, which are the quark-based particles. The name "baryon" comes from the Greek word for "heavy" (βαρύς, barys), because, at the time of their naming, most known elementary particles had lower masses than the baryons.