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

Baes, Maarten, Davies, Jonathan Ivor, Dejonghe, Herwig, Sabatini, Sabina ORCID: https://orcid.org/0000-0003-2076-5767, Roberts, Sarah G., Evans, Rhodri, Linder, Suzanne M., Smith, Rodney and de Blok, W. J. G. 2003. Radiative transfer in disc galaxies - III. The observed kinematics of dusty disc galaxies. Monthly Notices of the Royal Astronomical Society 343 (4) , pp. 1081-1094. 10.1046/j.1365-8711.2003.06770.x

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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.

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	Physics and Astronomy
Subjects:	Q Science > QB Astronomy
Uncontrolled Keywords:	radiative transfer; dust, extinction; galaxies: kinematics and dynamics; galaxies: spiral
Publisher:	Wiley
ISSN:	0035-8711
Last Modified:	08 Jul 2024 18:12
URI:	https://orca.cardiff.ac.uk/id/eprint/37764

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