Issue A&A Volume 439, Number 1, August III 2005 Page(s) 153 - 158 Section Interstellar and circumstellar matter DOI http://dx.doi.org/10.1051/0004-6361:20052951

A&A 439, 153-158 (2005)
DOI: 10.1051/0004-6361:20052951

Monte Carlo radiative transfer in SPH density fields

D. Stamatellos and A. P. Whitworth

School of Physics & Astronomy, Cardiff University, 5 The Parade, Cardiff CF24 3YB, Wales, UK
    e-mail: D.Stamatellos@astro.cf.ac.uk

(Received 28 February 2005 / Accepted 25 April 2005)

Abstract
We combine a Monte Carlo radiative transfer code with an SPH  code, so that - assuming thermal equilibrium - we can calculate dust-temperature fields, spectral energy distributions, and isophotal maps, for the individual time-frames generated by an SPH simulation. On large scales, the radiative transfer cells (RT cells) are borrowed from the tree structure built by the SPH code, and are chosen so that their size - and hence the resolution of the calculated temperature field - is comparable with the resolution of the density field. We refer collectively to these cubic RT cells as the global grid. The code is tested and found to treat externally illuminated dust configurations very well. However, when there are embedded discrete sources, i.e. stars, these produce very steep local temperature gradients which can only be modelled properly if - in the immediate vicinity of, and centred on, each embedded star - we supplement the global grid with a star grid of closely spaced concentric RT cells.

Key words: ISM: clouds -- ISM: structure -- ISM: dust, extinction -- methods: numerical -- radiative transfer -- hydrodynamics

© ESO 2005

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