The growth of galaxies is widely thought to be regulated by a combination of energy input from star formation and from growing supermassive black holes. One manifestation of this energy input is the frequent detection of “winds” of gas emanating from galaxy centers. The fate of these winds (i.e., does the material escape the galaxy, never to return?) and the physics governing the winds continues to be a topic of debate. The system NGC 6240, consisting of two strongly interacting galaxies, has been known for decades to host a large-scale “superwind”. More recent work has shown that the wind is multi-phase, with hot (X-ray emitting), warm (Hα), and cold (molecular gas) components.
In “Tracing the Ionization Structure of the Shocked Filaments of NGC 6240” (Medling+) we studied the inner portion of the superwind in NGC 6240, particularly in the bubbles and filaments that are seen in optical emission lines. We find that, on small scales, the molecular gas does not seem to be efficiently accelerated, and that the hot wind may be flowing around the bubbles (rather than destroying the bubbles). We also identify a region of shocked gas that maybe the physical interface of the two colliding galaxy disks.
The paper has been accepted for publication in The Astrophysical Journal and a preprint is available.