Atomic Hydrogen in a Galactic Center Outflow

TL;DR

This paper reports the discovery of small, high-velocity atomic hydrogen clouds near the Galactic Center, likely part of an outflow driven by star formation, with detailed observations of their properties and dynamics.

Contribution

It presents the identification and characterization of atomic hydrogen clouds associated with a Galactic Center outflow, a novel observation linking small-scale clouds to large-scale galactic winds.

Findings

Clouds have mean radius of 15 pc and velocity widths of ~14 km/s.

Clouds are observed up to 700 pc from the Galactic plane.

Velocity distribution shows no Galactic rotation signature.

Abstract

We describe a population of small, high velocity, atomic hydrogen clouds, loops, and filaments found above and below the disk near the Galactic Center. The objects have a mean radius of 15 pc, velocity widths of $\sim 14$ km/s and are observed at $|z|$ heights up to 700 pc. The velocity distribution of the clouds shows no signature of Galactic rotation. We propose a scenario where the clouds are associated with an outflow from a central star-forming region at the Galactic Center. We discuss the clouds as entrained material traveling at $\sim 200$ km/s in a Galactic wind.