The shape of dark matter haloes - III. Kinematics and structure of the HI disc
Date
2017
Authors
Peters, S. P C
van der Kruit, P C
Allen, R J
Freeman, Kenneth
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Publisher
Blackwell Publishing Ltd
Abstract
We present a new strategy for fitting the structure and kinematics of the HI in edge-on galaxies using a fit to the terminal-velocity channel maps of a HI data cube. The strategy can deal with self-absorbing HI gas and the presence of warps. The method is first tested on a series of models. We demonstrate that fitting optically thin models to real galaxies will lead to an overestimation of the thickness and velocity dispersion, and to a serious underestimation of the HI face-on column densities. We subsequently fit both self-absorption and optically thin models to the HI data of six edge-on galaxies. In three of these, we have also measured the velocity dispersion. On average, 27 ± 6 per cent of the total HI mass of edge-on galaxies is hidden by self-absorption. This implies that the HI mass, thickness and velocity dispersion of galaxies is typically underestimated in the literature. © 2016 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society
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Source
Monthly Notices of the Royal Astronomical Society
Type
Journal article