The Spectral Energy Distribution of Self-gravitating Interstellar Clouds I. Spheres

TL;DR

This paper models the spectral energy distribution of spherical, self-gravitating interstellar clouds under external radiation, revealing how pressure, mass, and radiation influence their observable emission across multiple wavelengths.

Contribution

It introduces a detailed radiative transfer model for self-gravitating clouds, incorporating non-isotropic scattering and multiple scattering effects, to analyze their SED and brightness profiles.

Findings

SED depends on pressure, mass fraction, and ISRF intensity.

Brightness profiles vary with wavelength, highlighting scattered and thermal emission.

Dust properties consistent with diffuse interstellar medium are assumed.

Abstract

We derive the spectral energy distribution (SED) of dusty, isothermal, self gravitating, stable and spherical clouds externally heated by the ambient interstellar radiation field. For a given radiation field and dust properties, the radiative transfer problem is determined by the pressure of the surrounding medium and the cloud mass expressed as a fraction of the maximum stable cloud mass above which the clouds become gravitational unstable. To solve the radiative transfer problem a ray-tracing code is used to accurately derive the light distribution inside the cloud. This code considers both non isotropic scattering on dust grains and multiple scattering events. The dust properties inside the clouds are assumed to be the same as in the diffuse interstellar medium in our galaxy. We analyse the effect of the pressure, the critical mass fraction, and the ISRF on the SED and present brightness profiles in the visible, the IR/FIR and the submm/mm regime with the focus on the scattered emission and the thermal emission from PAH-molecules and dust grains.