Young groups and clusters from GES and Gaia EDR3

We measure 3D velocity dispersions for all groups, which range from 0.61 to 7.4km/s (1D velocity dispersions of 0.35-4.3km/s). We find the majority of groups have anisotropic velocity dispersions, suggesting they are not dynamically relaxed.

From the 3D velocity dispersions, measured radii, and estimates of total mass, we estimate the virial state and find that all systems are super-virial when only the stellar mass is considered, but that some systems are sub-virial when the mass of the molecular cloud is taken into account. We observe an approximately linear correlation between the 3D velocity dispersion and the group mass, which would imply that the virial state of groups scales as the square root of the group mass.