27 Jun 2014
27 Jun 2014
Cosmic rays as regulators of molecular cloud properties
M. Padovani1,2,*, P. Hennebelle3, and D. Galli2
M. Padovani et al.
M. Padovani1,2,*, P. Hennebelle3, and D. Galli2
- 1Laboratoire de Radioastronomie Millimétrique, UMR 8112 du CNRS, École Normale Supérieure et Observatoire de Paris, 24 rue Lhomond, 75231 Paris cedex 05, France
- 2INAF–Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, 50125 Firenze, Italy
- 3CEA, IRFU, SAp, Centre de Saclay, 91191 Gif-Sur-Yvette, France
- *now at: Laboratoire Univers et Particules de Montpellier, UMR 5299 du CNRS, Université de Montpellier 2, place E. Bataillon, cc072, 34095 Montpellier, France
- 1Laboratoire de Radioastronomie Millimétrique, UMR 8112 du CNRS, École Normale Supérieure et Observatoire de Paris, 24 rue Lhomond, 75231 Paris cedex 05, France
- 2INAF–Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, 50125 Firenze, Italy
- 3CEA, IRFU, SAp, Centre de Saclay, 91191 Gif-Sur-Yvette, France
- *now at: Laboratoire Univers et Particules de Montpellier, UMR 5299 du CNRS, Université de Montpellier 2, place E. Bataillon, cc072, 34095 Montpellier, France
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Received: 27 Feb 2014 – Revised: 03 Jun 2014 – Accepted: 05 Jun 2014 – Published: 27 Jun 2014
Cosmic rays are the main agents in controlling the chemical evolution and setting the ambipolar diffusion time of a molecular cloud. We summarise the processes causing the energy degradation of cosmic rays due to their interaction with molecular hydrogen, focusing on the magnetic effects that influence their propagation. Making use of magnetic field configurations generated by numerical simulations, we show that the increase of the field line density in the collapse region results in a reduction of the cosmic-ray ionisation rate. As a consequence the ionisation fraction decreases, facilitating the decoupling between the gas and the magnetic field.
