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Paper: Morphological Diversities among the High Redshift Galaxies in GOODS
Volume: 380, At the Edge of the Universe: Latest Results from the Deepest Astronomical Surveys
Page: 489
Authors: Ravindranath, S.
Abstract: The deep, multi–wavelength images obtained by the Great Observatories Origins Deep Survey (GOODS) provide unprecedented large sample (~ 4700) of Lyman-break galaxies (LBGs) at z > 2.5, and starburst galaxies (~ 292) at z ~ 1.2. We present the results from morphological analysis based on light profile shape and ellipticity for ~ 1333 of the most luminous LBGs. About 40% of LBGs at z ~ 3 have exponential profiles, ~ 30% of the galaxies have steep (r1/4-like) profiles, and (~ 30%) of LBGs have multiple cores or disturbed morphologies suggestive of close pairs or mergers. The fraction of spheroid-like LBGs decreases by about 15% from z ~ 5 to 3. A comparison of LBGs with the starburst galaxies at z ~ 1.2, shows that disk-like and merger morphologies are dominant, but the fraction of spheroid-like profiles is about 20% higher among LBGs. The ellipticity distribution for LBGs exhibits a pronounced skew towards high ellipticities (ε > 0.5), which cannot be explained by morphologies similar to the local disks and spheroids viewed at random orientations. The peak of the distribution evolves toward lower , from 0.7 at z = 4 to ~ 0.5 at z = 3. The ellipticity distribution for the z ~ 1.2 galaxies is relatively flat similar to that seen for present–day galaxies. The dominance of elongated morphologies suggests that in a significant fraction of LBGs we may be witnessing star-formation in clumps along gas-rich filaments, or the earliest gas-rich bars that encompass essentially the entire visible galaxy.
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