The Skeleton of the Milky Way

Abstract

Recently, Goodman et al. (2014) argued that the very long, very thin infrared dark cloud "Nessie" lies directly in the Galactic mid-plane and runs along the Scutum-Centaurus arm in position-position-velocity (\(p-p-v\)) space as traced by lower density \(\rm {CO}\) and higher density \({\rm NH}_3\) gas. Nessie was presented as the first "bone" of the Milky Way, an extraordinarily long, thin, high-contrast filament that can be used to map our Galaxy's "skeleton." Here, we present evidence for additional bones in the Milky Way Galaxy, arguing that Nessie is not a curiosity but one of several filaments that could potentially trace Galactic structure. Our ten bone candidates are all long, filamentary, mid-infrared extinction features which lie parallel to, and no more than 20 pc from, the physical Galactic mid-plane. We use \(\rm {CO}\), \({\rm N}_2{\rm H}^+\), \(\rm {HCO}^+\), and \({\rm NH}_3\) radial velocity data to establish the three-dimensional location of the candidates in \({\it p-p-v}\) space. Of the ten candidates, six also: have a projected aspect ratio of \(\geqq\)50:1; run along, or extremely close to, the Scutum-Centaurus arm in \({\it p-p-v}\) space; and exhibit no abrupt shifts in velocity. The evidence presented here suggests that these candidates are marking the locations of significant spiral features, with the bone called filament 5 ("BC_18.88-0.09") being a close analog to Nessie in the Northern Sky. As molecular spectral-line and extinction maps cover more of the sky at increasing resolution and sensitivity, it should be possible to find more bones in future studies.

Journal

Publication date Created: 2015-06-29

Publication date Updated: 2015-12-20

Article

DOI: 10.1088/0004-637X/815/1/23

ArXiV ID: 1506.08807

License:

http://arxiv.org/licenses/nonexclusive-distrib/1.0/

Custom metadata

Journal reference ApJ, 815, 23 (2015)

Comments Update to author affiliation

Categories astro-ph.GA