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Paper: Morphology of z ∼ 1 Galaxies from Deep K-band AO Imaging in the COSMOS Field
Volume: 380, At the Edge of the Universe: Latest Results from the Deepest Astronomical Surveys
Page: 521
Authors: Huertas-Company, M.; Rouan, D.; Soucail, G.; Le Fevre, O.; Tasca, L.
Abstract: We present the results of observations of distant galaxies (z ~ 0.8) at high spatial resolution (~ 0.1) aiming at studying their morphological evolution. We observed 7 fields of 1′ 1′ with the NACO Adaptive Optics system (VLT) in Ks (2.2μm) band with typical V ~ 14 guide stars and 3h integration time per field. The K-band has the key advantage of probing old stellar populations at these redshifts, enabling us to determine galaxy morphological types unaffected by recent star formation, better linked to the underlying mass than classical optical morphology studies (HST). Observed fields are selected within the COSMOS survey area, in which multi-wavelength photometric and spectroscopic observations are on-going. We analyze the morphologies by means of B/D (Bulge/Disk) decomposition with GIM2D and CAS (Concentration-Asymmetry) estimators for 79 galaxies with magnitudes between Ks = 17 − 23 and classify them in three main morphological types (Late Type, Early Type and Irregulars). We obtain, for the first time an estimate of the mix of morphological types of the galaxy population up to z ≃ 1 from ground based K-band observations with high spatial resolution comparable or better than visible imaging from space. We demonstrate that estimating morphology from K-band data at z ≃ 1 is not affected by the morphological k correction, as there is no significant difference between our population and the corrected I-band population.
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