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J.M. Lotz, P. Madau (UC Santa Cruz), M. Giavalisco (STScI), J. Primack (UC Santa Cruz)
We apply a new approach for quantifying galaxy morphology and identifying galaxy mergers to the rest-frame far-ultraviolet images of 71 z ~4 Lyman break galaxies and 55 1.2 < z < 1.8 galaxies in the GOODS and Ultra Deep Fields. We compare the morphological distributions of the Gini coefficient (G), second-order moment of the brightest 20% of the galaxy light (M20; Lotz, Primack, & Madau 2004), and concentration (C) for high-z and low-z galaxies with average signal-to-noise per pixel > 2.5 and Petrosian radii > 0.3 arcsec. We find no strong morphological differences between the fainter UDF LBG sample and the brighter GOODS LBG sample nor between the z ~4 LBGs and the z ~1.5 galaxies. Ten of the 71 LBG have M20 > -1.1 and possess double or multiple bright nuclei, implying a major-merger fraction ~ 14%. Galaxies with bulge-dominated morphologies (G > 0.55, M20 < 1.6) make up ~30-40% of the z ~4 sample, while the remainder have G and M20 values higher than expected for smooth bulges and disks. The rest-frame FUV-B colors show no strong correlations with galaxy morphology. However, the two LBGs with colors indicative of strong 4000Åbreaks have bulge-like morphologies, as does the reddest z ~1.5 galaxy. J. M. L. acknowledges support from NASA, through NASA grant 9515 from the Space Telescope Science Institute, which is operated by AURA, under NASA contract NAS 5-26555.
The author(s) of this abstract have provided an email address for comments about the abstract: jlotz@ucolick.org
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Bulletin of the American Astronomical Society, 36 5
© 2004. The American Astronomical Society.