3D Cartesian Grid: Photoionization

A Monte Carlo code for photoionized nebulae is described by Wood, Mathis, & Ercolano (2004). The paper describes the physics incorporated into the code. It is best suited for simulations of low density ionized nebulae, HII regions, and the diffuse interstellar medium. The code disctretises the density structure on a linear grid, so has similar resolution issues to the scattered light codes. A document is given below that briefly describes the inputs, outputs, and how to set up the denity grid and point sources of ionizing photons. Directories containing the code and also model atmosphere files are given as gzipped tar files. The code is set up to reproduce the HII40 benchmark HII region described in Pequignot et al. (2001) and an IDL program ionfracs.pro reads in the output of the code and plots ion fractions and temperature throughout the grid for this 1D benchmark. The IDL program ratios_scatter.pro plots scatter plots for the intensity ratios ([S II]/H-alpha vs [N II]/H-alpha) and ([N II]/H-alpha vs H-alpha).

Gzipped tar file of a directory containing source code and required data files.

Gzipped tar file of a directory containing WMBASIC model atmosphere files.

PDF booklet describing code set up, inputs, and outputs.

This code is not as well documented as my other codes and I have not tidied up some of the subroutines that calculate ionization and temperature balance... but they do work. Consider this a beta-version, so please do send me email via the link below if you have questions on any aspects of the code, and especially if (when) you find bugs in it...

Kenny Wood

Code and gzipped tar file last updated: July 2013

Kenny Wood's photoionization lecture for the 2013 Monte Carlo Summer School: IONIZE_KW.PDF.

Barbara Ercolano's three lectures for the 2013 Monte Carlo Summer School: Erconano_1.pdf, Ercolano_2.pdf, Ercolano_3.pdf.