PDFCHEM: Fast simulations of the chemical ISM using probability distributions
1 I. Physikalisches Institut, Universität zu Köln, Zülpicher Straße 77, 50923 Köln, Germany
2 Department of Physics, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece
3 Max-Planck-Institut für Extraterrestrische Physik, Giessenbachstrasse 1, 85748 Garching, Germany
4 Leiden Observatory, Leiden University, P.O. Box 9513, 2300 RA Leiden, The Netherlands
* e-mail: firstname.lastname@example.org | thomasbisbas.com
Published online: 7 September 2022
We present PDFCHEM, a new numerical method able to compute the photodissociation region (PDR) chemistry of large-scale inhomogeneous ISM regions using probability distributions of physical parameters as an input. We distinguish between two visual extinctions, namely the ‘effective’ (AV,eff) referring to the local extinction and the ‘observed’ (AV,obs) referring to the extinction taken from observations. Using 1,200 pre-calculated PDR simulations, we apply PDFCHEM to two hypothetical AV,obs−PDFs, representing a diffuse region and a Giant Molecular Cloud. PDFchem is fast and can replace the computationally expensive hydrodynamical models in understanding the chemistry of the ISM in different environments, including at low metallicities and high cosmic-ray ionization rates.
© The Authors, Published by EDP Sciences, 2022
This is an Open Access article distributed under the terms of the Creative Commons Attribution License 4.0 (http://creativecommons.org/licenses/by/4.0/).