EPoS Contribution
EPoS Contribution
Star-Forming Content of the Galactic Giant Molecular Filaments

Miaomiao Zhang
MPIA, Heidelberg, DE
Observations have discovered numerous giant molecular filaments (GMFs) in the Milky Way and suggested them to occupy a special role in the Galaxy-scale star formation pattern. However, the studies so far have not confronted this suggestion with an analysis of star formation within the GMFs; the star formation activities of GMFs remain unknown. In this contribution, we present a systematic study of physical properties and star formation within all currently known GMFs. We first analyse gas properties, such as dense gas masses, using a homogenous approach for all GMFs. We then identify and classify the young stellar object (YSO) populations within each GMF using multi-wavelength photometry from near- to far-infrared. This allows us to estimate the star formation rates (SFRs) of the GMFs and to establish relationships between the SFRs and the GMF properties. We find that the median SFR surface density and star formation efficiency are similar to the nearby star-forming clouds, which indicates that the GMFs are not special objects from the perspective of star formation. We find no correlation between the SFR surface density and gas surface density, nor between SFR surface density and gas surface density per free-fall time. However, we find a significant correlation between SFR and dense gas mass and also a strong correlation between the SFR per unit length and line mass. Overall, our results discourage the use of gas surface densities as a predictor of SFR. The SFRs are more strongly linked to the dense gas mass and, in the case of filamentary clouds, to the line mass.
Caption: (a) The spatial distribution of YSOs in one GMF, including Class I sources (red) and Class II sources (blue). The contours show the Av levels of 3 and 7 mag; (b) The relation between SFR surface densities and gas surface densities per free-fall time for GMFs (black) and nearby molecular clouds (red).
Collaborators:
J. Kainulainen, OSO, SE
M. Mattern, MPIfR, DE
M. Fang, UA, US
Th. Henning, MPIA, DE
Suggested Session: Filaments