Mon. Not. R. Astron. Soc., 431, 2080-2105 (2013/May-3)
Properties and morphologies of Lyman break galaxies at z ∼ 1 in the Chandra Deep Field South, inferred from spectral energy distributions.
CHEN Z., SHU C.G., BURGARELLA D., BUAT V., HUANG J.-S. and LUO Z.J.
Abstract (from CDS):
After carefully cross-identifying previously discovered - and selected by the Galaxy Evolution Explorer (GALEX) - Lyman break galaxy (LBG) candidates one-to-one with their optical counterparts in the field of the Chandra Deep Field South (CDF-S), we re-estimate their photometric redshifts using multiwavelength data from ultraviolet and optical to near-infrared. Considering their re-estimated photometric redshifts and spectral energy distributions, we refine a new updated sample of 383 LBGs at 0.7 ≲ z ≲ 1.4, with two confirmed active galactic nuclei being excluded. There are 260 and 111 LBGs classified as starburst and irregular types, respectively. The ages of the LBGs span from several Myr to 1.5 Gyr with a median of ∼ 50 Myr. Their dust-corrected star formation rates (SFRs) and stellar masses (M*) are 4-220 M☉ yr-1 and from 2.3x108 to 4x1011 M☉, with median values of ∼ 25 M☉ yr-1 and ∼ 1010 M☉. The rest-frame far-ultraviolet luminosity function of the LBGs is presented with the best-fitting Schechter parameters of α = -1.61±0.40, M* = -20.40±0.22 and φ* = (0.89±0.30)x10-3 Mpc-3 dex-1. LBGs of irregular types are mainly distributed along the main sequence of star-forming galaxies, while most LBGs of starburst types are located in the starburst region. Together with previous studies, we suggest that the star formation mode for LBGs at z > 3 is mainly starburst, and that it evolves to be more significant to the quenching mode after z ∼ 3. A downsizing effect is clearly found, and we discuss the physical implications and comparisons with previous studies in detail. LBGs with larger SFRs are, on average, more compact. In the rest-frame colour (U - B)-M* diagram, LBGs are distributed in the `blue' cloud. We suggest that LBGs might evolve along the blue cloud from later to earlier types. The Hubble Space Telescope images in F606W (V band) and F850LP (z band) are taken from the Galaxy Evolution from Morphology and SEDs (GEMS) survey and the Great Observatories Origins Deep Survey South (GOODS-S) for morphological studies of LBGs. sextractor and galfit are applied in order to obtain their morphological parameters. We establish an image gallery of 277 LBGs, commonly detected in both bands, by visually classifying individual LBGs into the following types: chain, spiral, tadpole, bulge and clump. We define a morphological sample of 142 LBGs with reliable results of Sérsic indices and sizes in both bands. We find that LBGs at z ∼ 1 are dominated by disc-like galaxies, with median sizes of 2.34 and 2.68 kpc in F606W and F850LP, respectively. The correlations between the photometric and morphological properties of LBGs are investigated. Strong correlations between their half-light radii and M* (i.e. size-stellar mass relations) are found in both bands. We discuss the physical connections between the correlations and the downsizing effect.
© 2013 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society (2013)
galaxies: evolution - galaxies: formation - galaxies: luminosity function, mass function - galaxies: statistics - galaxies: structure
VizieR on-line data:
<Available at CDS (J/MNRAS/431/2080): table5.dat table6.dat table6.pdf>
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