Dependence of Galaxy Structure on Rest-Frame Wavelength and Galaxy Type

• Published in: The Astrophysical journal Vol. 659; no. 1; pp. 162 - 187
• Main Authors: Taylor-Mager, Violet A, Conselice, Christopher J, Windhorst, Rogier A, Jansen, Rolf A
• Format: Journal Article
• Language: English
• Published: Chicago, IL IOP Publishing 10-04-2007; University of Chicago Press
• Subjects: Astronomy; Earth, ocean, space; Exact sciences and technology; Galaxy evolution; Red shift; Galaxies; Galaxy structure; galaxies: evolution; galaxies: fundamental parameters; galaxies: structure Online material: machine-readable tables; galaxies: high-redshift
• ISSN: 0004-637X; 1538-4357
• DOI: 10.1086/511806

We present a quantitative analysis of the morphologies for 199 nearby galaxies as parameterized with measurements of the concentration, asymmetry, and clumpiness (CAS) parameters at wavelengths from 0.15 to 0.85 mu m. We find that these CAS parameters depend on both galaxy type and the wavelength of observation. As such, we use them to obtain a quantitative measure of the "morphological k-correction," i.e., the change in appearance of a galaxy with rest-frame wavelength. Whereas early-type galaxies (E-S0) appear about the same at all wavelengths longward of the Balmer break, there is a mild but significantly determined wavelength dependence of the CAS parameters for galaxy types later than S0, which generally become less concentrated and more asymmetric and clumpy toward shorter wavelengths. Also, as a merger progresses from premerger via major-merger to merger-remnant stages, it evolves through the CAS parameter space, becoming first less concentrated and more asymmetric and clumpy, and then returning toward the "locus" of normal galaxies. The final merger products are, on average, much more concentrated than normal spiral galaxies.