Rest-Frame UV Versus Optical Morphologies of Galaxies Using Sérsic Profile Fitting: The Importance of Morphological K-Correction

• Published in: The Astrophysical journal 2009-04, Vol.695 (2), p.1315-1326
• Main Authors: Rawat, Abhishek, Wadadekar, Yogesh, De Mello, Duilia
• Format: Article
• Language: English
• Subjects: Astronomy; Earth, ocean, space; Exact sciences and technology
• ISSN: 0004-637X; 1538-4357
• DOI: 10.1088/0004-637X/695/2/1315

We show a comparison of the rest-frame UV morphologies of a sample of 162 intermediate-redshift (z median = 1.02) galaxies with their rest-frame optical morphologies. We select our sample from the deepest near-UV image obtained with the Hubble Space Telescope (HST) using the Wide Field Planetary Camera 2 (WFPC2; F300W) as part of the parallel observations of the Hubble Ultra Deep Field campaign overlapping with the HST/ACS Great Observatories Origins Deep Survey data set. We perform single-component Sersic fits in both WFPC2/F300W (rest-frame UV) and ACS/F850LP (rest-frame optical) bands and deduce that the Sersic index n is estimated to be smaller in the rest-frame UV compared to the rest-frame optical, leading to an overestimation of the number of merger candidates by ~40%-100% compared to the rest-frame optical depending upon the cutoff in n employed for identifying merger candidates. This effect seems to be dominated by galaxies with low values of n(F300W) = 0.8) objects are higher by a factor of ~2.8 compared to the rest-frame optical. This indicates that the reported dominance of elongated morphologies among high-z Lyman Break Galaxies might just be a bias related to the use of rest-frame UV data sets in high-z studies.