Molecular clouds have power-law probability distribution functions

Author(s)
Marco Lombardi, João Alves, Charles J. Lada
Abstract

In this Letter we investigate the shape of the probability distribution of column densities (PDF) in molecular clouds. Through the use of low-noise, extinction-calibrated Herschel/Planck emission data for eight molecular clouds, we demonstrate that, contrary to common belief, the PDFs of molecular clouds are not described well by log-normal functions, but are instead power laws with exponents close to two and with breaks between A

K ≃ 0.1 and 0.2 mag, so close to the CO self-shielding limit and not far from the transition between molecular and atomic gas. Additionally, we argue that the intrinsic functional form of the PDF cannot be securely determined below A

K ≃ 0.1 mag, limiting our ability to investigate more complex models for the shape of the cloud PDF.

Organisation(s)
Department of Astrophysics
External organisation(s)
Harvard-Smithsonian Center for Astrophysics, Università degli Studi di Milano-Bicocca
Journal
Astronomy & Astrophysics
Volume
576
No. of pages
4
ISSN
0004-6361
DOI
https://doi.org/10.1051/0004-6361/201525650
Publication date
03-2015
Peer reviewed
Yes
Austrian Fields of Science 2012
103003 Astronomy, 103004 Astrophysics
Keywords
ASJC Scopus subject areas
Astronomy and Astrophysics, Space and Planetary Science
Portal url
https://ucrisportal.univie.ac.at/en/publications/1de34621-9387-4e93-b38d-c96b368b38ef