|
EPoS |
|
EPoS Contribution
|
|
The cosmic-ray ionization rate in nearby clouds
Gan Luo IRAM, Grenoble, FR | |
| The cosmic-ray ionization rate (CRIR) is one of the key parameters in star formation, since it regulates the chemical and dynamical evolution of molecular clouds by ionizing the molecules and determining the coupling between the magnetic field and gas. To date, the majority of the CRIR measurements are from ions (e.g., H3+, OH+, and H2O+), which are hard to detect and require the existence of background massive stars. In this talk, I will introduce our new methodologies to infer CRIR in both low-to-intermediate density gas and hot molecular cores. We find CRIR decreases as the increasing column density across the cloud boundary, which coincides with the cosmic-ray (CR) attenuation models, supporting the idea of CR attenuation with increasing column density. We find the values of CRIR are more than an order of magnitude higher in hot molecular cores than the infrared dark clouds and the theoretical prediction of CR attenuation models, favoring the scenario that locally accelerated cosmic rays in embedded protostars should be responsible for the high CRIR. | |
 | |
| Caption: A comparison of inferred ζ2 from H3+ (blue squares, Indriolo & McCall 2012), our work (red and brown points). The CR attenuation models L (solid), H (dashed), and with low-energy spectral slope α=-1.2 (dash-dotted) are overlaid (Padovani et al. 2022). | |
| Collaborators: Z.Y. Zhang, NJU, CN T. Bisbas, ZJL, CN D. Li, NAOC, CN M. Padovani, INAF, IT B. Gaches, Chalmers, SE |
Relevant topic(s): Chemistry Cosmic Rays Molecular Clouds |
| Relevant Big Question: How does the cosmic-ray ionization rate vary with the environments? | |