MUSEQuBES: The kinematics of OVI-bearing gas in and around low-redshift galaxies

TL;DR

This study investigates the kinematics of OVI-bearing gas around low-mass galaxies at low redshift, revealing that most gas within the virial radius is gravitationally bound and that kinematic properties vary with impact parameter and galaxy mass.

Contribution

It provides new insights into the gravitational binding and kinematic behavior of OVI gas around low-redshift galaxies, using a large sample and detailed velocity analysis.

Findings

Most OVI absorbers within the virial radius are gravitationally bound.

Kinematic scatter decreases with impact parameter beyond 2 virial radii.

Higher mass galaxies show larger OVI kinematic spread, which normalizes when scaled by circular velocity.

Abstract

We present a detailed study of the kinematics of OVI-bearing gas around 60 low-mass (median log(M*/Msun)~8.9) galaxies at low redshift (0.1 < z < 0.7) using background quasars (median impact parameter $\approx115$ kpc) as part of the MUSE Quasar-fields Blind Emitters Survey (MUSEQuBES). We find that the majority of the OVI absorbers detected within the virial radius have line-of-sight velocities smaller than the escape velocities and are thus consistent with being gravitationally bound, irrespective of the halo mass. However, the fraction of such absorbers declines at larger impact parameters. The Doppler $b$ parameter and the velocity width ($\Delta v_{90}$) of the OVI absorbers exhibit large scatter inside the virial radius of the host galaxies, but the scatter declines sharply at impact parameter $D \gtrsim 2R_{\rm vir}$. For high-mass galaxies (log(M*/Msun)>9), OVI absorption displays a larger kinematic spread, quantified by the pixel-velocity two-point correlation function (TPCF). However, this difference disappears for the isolated galaxies when the pixel velocities are scaled by the galaxy's circular velocity. We do not find any significant difference between the TPCF of isolated and group galaxies when the stellar mass is controlled for. A significant fraction of groups (4/6) with four or more member galaxies do not show any detectable OVI absorption, likely due to the passive nature of nearest galaxies.