# MusE GAs FLOw and Wind (MEGAFLOW) II. A study of gas accretion around $z\approx1$ star-forming galaxies with background quasars

## TL;DR

This study uses combined spectroscopic observations to analyze cold gas kinematics around $z
oughly1$ star-forming galaxies, revealing disk-like structures and inflow patterns consistent with galaxy growth and star formation needs.

## Contribution

It provides new observational evidence of co-rotating gas disks and inflow velocities around high-redshift galaxies, linking absorption features to galaxy dynamics.

## Key findings

- Gas absorption is mainly in outflow cones and extended disks.
- Most gas is co-rotating with galaxy disks.
- Inflow velocities match simulation predictions and sustain star formation.

## Abstract

We use the MusE GAs FLOw and Wind (MEGAFLOW) survey to study the kinematics of extended disk-like structures of cold gas around $z\approx1$ star-forming galaxies. The combination of VLT/MUSE and VLT/UVES observations allows us to connect the kinematics of the gas measured through MgII quasar absorption spectroscopy to the kinematics and orientation of the associated galaxies constrained through integral field spectroscopy. Confirming previous results, we find that the galaxy-absorber pairs of the MEGAFLOW survey follow a strong bimodal distribution, consistent with a picture of MgII absorption being predominantly present in outflow cones and extended disk-like structures. This allows us to select a bona-fide sample of galaxy-absorber pairs probing these disks for impact parameters of 10-70 kpc. We test the hypothesis that the disk-like gas is co-rotating with the galaxy disks, and find that for 7 out of 9 pairs the absorption velocity shares the sign of the disk velocity, disfavouring random orbits. We further show that the data are roughly consistent with inflow velocities and angular momenta predicted by simulations, and that the corresponding mass accretion rates are sufficient to balance the star formation rates.