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Molecular clouds are complex magnetized structures, with variations over a broad range of length scales. Ionization in dense, shielded clumps and cores of molecular clouds is thought to be caused by charged cosmic rays (CRs). These CRs can also contribute to heating the gas deep within molecular clouds, and their effect can be substantial in environments where CRs are abundant. CRs propagate predominantly by diffusion in media with disordered magnetic fields. The complex magnetic structures in molecular clouds therefore determine the propagation and spatial distribution of CRs within them, and hence regulate their local ionization and heating patterns. Optical and near-infrared (NIR) polarization of starlight through molecular clouds is often used to trace magnetic fields. The coefficients of CR diffusion in magnetized molecular cloud complexes can be inferred from the observed fluctuations in these optical/NIR starlight polarisations. Here, we present calculations of the expected CR heating patterns in the star-forming filaments of IC 5146, determined from optical/NIR observations. Our calculations show that local conditions give rise to substantial variation in CR propagation. This affects the local CR heating power. Such effects are expected to be severe in star-forming galaxies rich in CRs. The molecular clouds in these galaxies could evolve differently to those in galaxies where CRs are less abundant.
Cosmic-rays constitute the main ionising and heating agent in dense, starless, molecular cloud cores. We reexamine the physical quantities necessary to determine the cosmic-ray ionisation rate (especially the cosmic ray spectrum at E < 1 GeV and the
Cosmic rays pervade the Galaxy and are thought to be accelerated in supernova shocks. The interaction of cosmic rays with dense interstellar matter has two important effects: 1) high energy (>1 GeV) protons produce {gamma}-rays by {pi}0-meson decay;
We present the implementation and the first results of cosmic ray (CR) feedback in the Feedback In Realistic Environments (FIRE) simulations. We investigate CR feedback in non-cosmological simulations of dwarf, sub-$Lstar$ starburst, and $Lstar$ gala
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 phys
The local cosmic-ray (CR) spectra are calculated for typical characteristic regions of a cold dense molecular cloud, to investigate two so far neglected mechanisms of dust charging: collection of suprathermal CR electrons and protons by grains, and p