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