A Photometric Method for Quantifying Asymmetries in Disk Galaxies
Abstract
A photometric method for quantifying deviations from axisymmetry in optical images of disk galaxies is applied to a sample of 32 face-on and nearly face-on spirals. The method involves comparing the relative fluxes contained within trapezoidal sectors arranged symmetrically about the galaxy center of light, excluding the bulge and/or barred regions. Such a method has several advantages over others, especially when quantifying asymmetry in flocculent galaxies. Specifically, the averaging of large regions improves the signal-to-noise in the measurements; the method is not strongly affected by the presence of spiral arms; and it identifies the kinds of asymmetry that are likely to be dynamically important. Application of this "method of sectors" to R-band images of 32 disk galaxies indicates that about 30% of spirals show deviations from axisymmetry at the 5-sigma level.
Cite
@article{arxiv.astro-ph/9807304,
title = {A Photometric Method for Quantifying Asymmetries in Disk Galaxies},
author = {David A. Kornreich and Martha P. Haynes and Richard V. E. Lovelace},
journal= {arXiv preprint arXiv:astro-ph/9807304},
year = {2009}
}
Comments
17 pages, 2 tables and 6 figures, uses psfig and AAS LaTex; to appear in AJ