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Galaxy structure in the ultraviolet: the dependence of morphological parameters on rest-frame wavelength

Mager, Violet A.; Conselice, Christopher J.; Seibert, Mark; Gusbar, Courtney; Katona, Anthony P.; Villari, Joseph M.; Madore, Barry F.; Windhorst, Rogier A.


Violet A. Mager

Christopher J. Conselice

Mark Seibert

Courtney Gusbar

Anthony P. Katona

Joseph M. Villari

Barry F. Madore

Rogier A. Windhorst


Evolutionary studies that compare galaxy structure as a function of redshift are complicated by the fact that any particular galaxy's appearance depends in part on the rest-frame wavelength of the observation. This leads to the necessity for a "morphological k-correction" between different passbands, especially when comparing the rest-frame optical or infrared (IR) to the ultraviolet (UV). This is of particular concern for high-redshift studies that are conducted in the rest-frame UV. We investigate the effects of this "bandpass shifting" out of the UV by quantifying nearby galaxy structure via concentration, asymmetry, and clumpiness (CAS) parameters. For this study we combine panchromatic data from the UV through the near-IR with Galaxy Evolution Explorer (GALEX) data of 2073 nearby galaxies in the "near-UV" (NUV; ~230 nm) and 1127 in the "far-UV" (FUV; ~150 nm), providing the largest study of this kind in the mid- to far-UV. We find a relationship between the CAS parameters and observed rest-frame wavelength that make galaxies appear more late-type at shorter wavelengths, particularly in the UV. The effect is strongest for E/S0 galaxies in the far-UV, which have concentrations and asymmetries that more closely resemble those of spiral and peculiar/merging galaxies in the optical. This may be explained by extended disks containing recent star formation. Here, we also release the CAS values of the galaxies imaged in GALEX NUV and FUV for use in comparisons with deep Hubble Space Telescope imaging and the James Webb Space Telescope in the future.


Mager, V. A., Conselice, C. J., Seibert, M., Gusbar, C., Katona, A. P., Villari, J. M., …Windhorst, R. A. (2018). Galaxy structure in the ultraviolet: the dependence of morphological parameters on rest-frame wavelength. Astrophysical Journal, 864(2), Article 123.

Journal Article Type Article
Acceptance Date Jul 8, 2018
Online Publication Date Sep 5, 2018
Publication Date Sep 10, 2018
Deposit Date Oct 8, 2018
Publicly Available Date Oct 8, 2018
Journal Astrophysical Journal
Print ISSN 1538-4357
Electronic ISSN 1538-4357
Publisher American Astronomical Society
Peer Reviewed Peer Reviewed
Volume 864
Issue 2
Article Number 123
Keywords Space and planetary science; Astronomy and astrophysics; Galaxies; Evolution; Structure
Public URL
Publisher URL
Additional Information © 2018. The American Astronomical Society. All rights reserved.


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