Observational Signatures of Cosmic-Ray Interactions in Molecular Clouds

We investigate ionization and heating of gas in the dense, shielded clumps/cores of molecular clouds bathed by an influx of energetic, charged cosmic rays (CRs). These molecular clouds have complex structures, with substantial variation in their physical properties over a wide range of length scales...

Full description

Saved in:
Bibliographic Details
Published in:The Astrophysical journal 2021-05, Vol.913 (1), p.52
Main Authors: Owen, Ellis R., On, Alvina Y. L., Lai, Shih-Ping, Wu, Kinwah
Format: Article
Language:English
Subjects:
Astrophysics
Clouds
Clumps
Cores
Cosmic ray showers
Cosmic rays
Filaments
Flux density
Galactic cosmic rays
Heating rate
Interstellar clouds
Interstellar magnetic fields
Ionization
Magnetic fields
Mathematical analysis
Molecular clouds
Physical properties
Propagation
Star formation
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:We investigate ionization and heating of gas in the dense, shielded clumps/cores of molecular clouds bathed by an influx of energetic, charged cosmic rays (CRs). These molecular clouds have complex structures, with substantial variation in their physical properties over a wide range of length scales. The propagation and distribution of CRs is thus regulated accordingly, in particular, by the magnetic fields threaded through the clouds and into the dense regions within. We have found that a specific heating rate reaching 10 −26 erg cm −3 s −1 can be sustained in the dense clumps/cores for Galactic environments, and this rate increases with CR energy density. The propagation of CRs and heating rates in some star-forming filaments identified in IC 5146 are calculated, with the CR diffusion coefficients in these structures determined from magnetic field fluctuations inferred from optical and near-infrared polarizations of starlight, which is presumably a magnetic field tracer. Our calculations indicate that CR heating can vary by nearly three orders of magnitude between different filaments within a cloud due to different levels of CR penetration. The CR ionization rate among these filaments is similar. The equilibrium temperature that could be maintained by CR heating alone is of order 1 K in a Galactic environment, but this value would be higher in strongly star-forming environments, thus causing an increase in the Jeans mass of their molecular clouds.
ISSN:0004-637X
1538-4357
DOI:10.3847/1538-4357/abee1a