Characteristic scale of star formation. I. Clump formation efficiency on local scales
View/ Open
Author
Eden, D. J.
Moore, T. J. T.
Plume, R.
Rigby, A. J.
Urquhart, J. S.
Marsh, K. A.
Peñaloza, C. H.
Clark, P. C.
Smith, M. W. L.
Tahani, K.
Ragan, S. E.
Thompson, M. A.
Johnstone, D.
Parsons, H.
Rani, R.
Attention
2299/23864
Abstract
We have used the ratio of column densities (CDR) derived independently from the 850-$\mu$m continuum JCMT Plane Survey (JPS) and the $^{13}$CO/C$^{18}$O $(J=3-2)$ Heterodyne Inner Milky Way Plane Survey (CHIMPS) to produce maps of the dense-gas mass fraction (DGMF) in two slices of the Galactic Plane centred at $\ell$=30$^{\circ}$ and $\ell$=40$^{\circ}$. The observed DGMF is a metric for the instantaneous clump-formation efficiency (CFE) in the molecular gas. We split the two fields into velocity components corresponding to the spiral arms that cross them, and a two-dimensional power-spectrum analysis of the spiral arm DGMF maps reveals a break in slope at the approximate size scale of molecular clouds. We interpret this as the characteristic scale of the amplitude of variations in the CFE and a constraint on the dominant mechanism regulating the CFE and, hence, the star-formation efficiency in CO-traced clouds.