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Astron. Astrophys. 354, L21-L24 (2000)

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5. Implications for high-redshift galaxies

The origins and triggering mechanisms of the increasingly abundant and luminous starbursts observed at intermediate and high z are still an issue of debate. Merging is invoked as a likely candidate for triggering because the physical volume of the universe decreases at earlier times, however this has not been demonstrated directly. The physical-morphological method outlined in this paper can be used to determine if merging is indeed the culprit. If these star-forming galaxies at high z are triggered by interactions/mergers then their positions in the CAD would be similar those for the starbursts presented in this paper. If the interactions/mergers are minor, then their locations would fall near the normal galaxy fiducial sequence, similar to NGC 3310.

In principle, the high resolution of the Hubble Space Telescope allows detailed morphological studies of distant galaxies. For example, asymmetry has previously been used in conjunction with the concentration of light for galaxies in the Hubble Deep Field (Abraham et al. 1996) and other WFPC-2 images (Jangren et al. 2000). The method used to compute the asymmetries in Abraham et al.'s study differ in several important respects from the method used here and by Jangren et al. In particular, Conselice et al. (2000b) demonstrated that high angular resolution ([FORMULA] 0.1 arcsec FWHM) is critical for the study of distant galaxy asymmetry. While deep NICMOS images of the Hubble Deep Field allow an unprecedented opportunity to study the rest frame optical morphology of high-z galaxies, adaptive optics on large, ground-based telescope or the Next Generation Space Telescope may ultimately prove critical for the study of asymmetries in distant galaxies.

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© European Southern Observatory (ESO) 2000

Online publication: January 31, 2000