SPAMCART: a code for smoothed particle Monte Carlo radiative transfer

TL;DR

SPAMCART is a Monte Carlo radiative transfer code that generates synthetic spectral energy distributions and maps directly from SPH simulations, maintaining the same resolution as the hydrodynamics without grid mapping.

Contribution

The code implements a gridless Monte Carlo radiative transfer method for SPH data, allowing accurate and resolution-preserving synthetic observations from hydrodynamic simulations.

Findings

Code adheres to Kirchhoff's law of radiation.

Produced synthetic spectra and intensity maps of protostellar systems.

Abstract

We present a code for generating synthetic SEDs and intensity maps from Smoothed Particle Hydrodynamics simulation snapshots. The code is based on the Lucy (1999) Monte Carlo Radiative Transfer method, i.e. it follows discrete luminosity packets, emitted from external and/or embedded sources, as they propagate through a density field, and then uses their trajectories to compute the radiative equilibrium temperature of the ambient dust. The density is not mapped onto a grid, and therefore the calculation is performed at exactly the same resolution as the hydrodynamics. We present two example calculations using this method. First, we demonstrate that the code strictly adheres to Kirchhoff's law of radiation. Second, we present synthetic intensity maps and spectra of an embedded protostellar multiple system. The algorithm uses data structures that are already constructed for other purposes in modern particle codes. It is therefore relatively simple to implement.