Radiative transfer in disc galaxies - III. The observed kinematics of dusty disc galaxies

Date

2003

Authors

Baes, M.
Davies , J. I.
Dejonghe, H.
Sabatini, S.
Roberts, Sarah
Evans, Rhodri
Linder, S.
Smith, R. M.
de Blok, Willem

Journal Title

Journal ISSN

Volume Title

Publisher

Blackwell Publishing Ltd

Abstract

We present SKIRT (Stellar Kinematics Including Radiative Transfer), a new Monte Carlo radiative transfer code that allows the calculation of the observed stellar kinematics of a dusty galaxy. The code incorporates the effects of both absorption and scattering by interstellar dust grains, and calculates the Doppler shift of the emerging radiation exactly by taking into account the velocities of the emitting stars and the individual scattering dust grains. The code supports arbitrary distributions of dust through a cellular approach, whereby the integration through the dust is optimized by means of a novel efficient trilinear interpolation technique. We apply our modelling technique to calculate the observed kinematics of realistic models for dusty disc galaxies. We find that the effects of dust on the mean projected velocity and projected velocity dispersion are severe for edge-on galaxies. For galaxies which deviate more than a few degrees from exactly edge-on, the effects are already strongly reduced. As a consequence, dust attenuation cannot serve as a possible way to reconcile the discrepancy between the observed shallow slopes of the inner rotation curves of low surface brightness galaxies and the predictions of cold dark matter cosmological models. For face-on galaxies, the velocity dispersion increases with increasing dust mass owing to scattering, but the effects are limited, even for extended dust distributions. Finally, we show that serious errors can be made when the individual velocities of the dust grains are neglected in the calculations.

Description

Keywords

Keywords: Dust, extinction; Galaxies: kinematics and dynamics; Galaxies: spiral; Radiative transfer

Citation

Source

Monthly Notices of the Royal Astronomical Society

Type

Journal article

Book Title

Entity type

Access Statement

License Rights

DOI

10.1046/j.1365-8711.2003.06770.x

Restricted until

2037-12-31