RADICAL: A multi-purpose 2-D radiative transfer code

C.P. Dullemond, R. Mokiem, R. Turolla

Zooming in to a Herbig Ae/Be star protoplanetary disk with a gap.
The gap divides the disk into an outer and an inner disk. The inner disk has a central cavity due to
the evaporation of dust. As a result of the direct face-on irradiation the inner rim is overheated
and very bright. This rim produces the famous "3-micron bump" in the SEDs of Herbig Ae/Be stars.
The temperature and density structure were self-consistently computed with RADICAL.

RADICAL is a multi-purpose 2-D radiative transfer code for axi-symmetric circumstellar (or circum-black-hole) envelopes /disks / tori etc. It has been developed over a period of 4 years, partly at the observatory at the university of Leiden, partly at the Max Planck Institute for Astrophysics in Garching and partly at the Institute of Astronomy at the University of Amsterdam . It has been extensively tested and found reliable and accurate (see e.g. Benchmark tests for radiative transfer in Molecular Lines and a benchmark project for 2-D circumstellar disks by Ilaria Pascucci et al.).

The code is not yet public domain. But anyone who is interested can contact dullemon@mpia.de.

A paper describing the basic short characteristics integration scheme used in the code can be found here. Many additions have since been made, most of which are not yet described in any published document. Most importantly, the code has recently been supplemented with a Variable Eddington Tensor module which enables it to solve dust continuum radiative transfer problems from very low up to extremely high optical depths with only a few (about 7) iterations at most. This will be described in a future paper.

Included processes:

  • Multi-level atomic/molecular line transfer with a proper inclusion of gas velocities. It can include microwave background radiation as an outer boundary condition. Convergence acceleration techniques are: ALI (Accelerate Lamda Iteration), and Ng acceleration.
  • Dust continuum transfer. It solves dust temperatures by requiring radiative equilibrium of the dust grains. It includes scattering (in isotropic approximation), multiple grain species, and size-distributions. Evaporation of grains, and even temperature dependent grain opacities can be included. Convergence acceleration techniques are: ALI (Accelerate Lamda Iteration), and Ng acceleration, and most recently: a Variable Eddington Tensor module for quick solution of high-optical-depth problems.
  • Electron scattering / Compton scattering, in the isotropic approximation.

Output:

  • Spectra at any inclination
  • Images at any inclination and frequency
  • Dust temperature distribution
  • Molecular level populations

Included special features:

  • (For disks): self-consistent vertical hydrostatic structure
  • (For dust continuum): Variable Eddington Tensor module for very quick and robust solutions to the dust continuum transfer equation at arbitrarily high optical depths.
  • IDL widget front-end for image rendering
  • NEW: Variable Eddington Tensor module for solving high optical depth continuum transfer problems

THIS PAGE IS STILL UNDER CONSTRUCTION. TO APPEAR SOON:

If you are interested in this code, please contact me at dullemon@mpia.de.

dullemon@mpia.de