http://arxiv.org/abs/1705.06550
We present a method to derive the density scaling relation $\langle n\rangle \propto L^{-\alpha}$ in regions of star formation or in their turbulent vicinities from straightforward binning of the column-density distribution ($N$-pdf). The outcome of the method is studied for three types of $N$-pdf: power law ($7/5\le\alpha\le5/3$), lognormal ($0.7\lesssim\alpha\lesssim1.4$) and combination of lognormals. In the last case, the method of Stanchev et al. (2015) was also applied for comparison and a very weak (or close to zero) correlation was found. We conclude that the considered `binning approach’ reflects rather the local morphology of the $N$-pdf with no reference to the physical conditions in a considered region. The rough consistency of the derived slopes with the widely adopted Larson’s (1981) value $\alpha\sim1.1$ is suggested to support claims that the density-size relation in molecular clouds is indeed an artifact of the observed $N$-pdf.
T. Veltchev, S. Donkov and O. Stanchev
Fri, 19 May 17
13/62
Comments: 11 pages, 4 figures; to appear in the Bulgarian Astronomical Journal, vol. 27, 2017