Please use this identifier to cite or link to this item: http://hdl.handle.net/1959.3/229437

Title

Rotational widths for use in the Tully-Fisher relation II: the impact of surface brightness

Author(s)

Catinella, Barbara;  Haynes, Martha P.;  Giovanelli, Riccardo

Abstract

Using a large sample of spiral galaxies for which 21 cm single-dish and/or long-slit optical spectra are available, we make a detailed comparison between various estimates of rotational widths. Different optical width estimators are considered and their limitations discussed, with emphasis on biases associated with rotation curve properties (shape and extent) and disk central surface brightness. The best match with H I rotational velocities is obtained with Polyex widths, which are measured at the optical radius (encompassing a fixed fraction of the total light of the galaxy) from a model fit to the rotation curve. In contrast with Polyex widths, optical rotational velocities measured at 2.15 disk scale lengths rd deviate from H I widths by an amount that correlates with the central surface brightness of the disk. This bias occurs because the rotation curves of galaxies are in general still rising at 2.15rd, and the fraction of total mass contained within this radius decreases with increasing disk surface brightness. Statistical corrections, parameterized by the radial extent of the observed rotation curve, are provided to reduce Polyex and H I width measurements into a homogeneous system. This yields a single robust estimate of rotational velocity to be used for applications of disk scaling relations.

Publication type

Journal article

Source

Astronomical Journal, Vol. 134, no. 1 (Jul 2007), pp. 334-343

Publication year

2007

FOR Code(s)

0201 Astronomical and Space Sciences

Keyword(s)

Cosmology observations;  Distances;  Galaxy kinematics and dynamics;  Galaxy structure;  Red shift;  Spiral galaxies

Publisher

Institute of Physics Publishing

ISSN

0004-6256

Publisher URL

http://dx.doi.org/10.1086/518827

Copyright

Copyright © 2007 The American Astronomical Society. All rights reserved. The American Astronomical Society does not allow Swinburne Research Bank to archive either the accepted manuscript or the published version of the article. However you can find an earlier version of the full text here: http://arxiv.org/abs/0704.2209

Peer reviewed