CLUMPY GALAXIES IN CANDELS. I. THE DEFINITION OF UV CLUMPS AND THE FRACTION OF CLUMPY GALAXIES AT 0.5 < z < 3

Although giant clumps of stars are thought to be crucial to galaxy formation and evolution, the most basic demographics of clumps are still uncertain, mainly because the definition of clumps has not been thoroughly discussed. In this paper, we carry out a study of the basic demographics of clumps in...

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Published in:The Astrophysical journal 2015-02, Vol.800 (1), p.1-21
Main Authors: Guo, Yicheng, Ferguson, Henry C, Bell, Eric F, Koo, David C, Conselice, Christopher J, Giavalisco, Mauro, Kassin, Susan, Lu, Yu, Lucas, Ray, Mandelker, Nir
Format: Article
Language:English
Subjects:
ASTROPHYSICS, COSMOLOGY AND ASTRONOMY
AXIAL RATIO
Clumps
Demographics
Dimming
GALAXIES
Galaxy formation
H II regions
MASS
RED SHIFT
SPATIAL RESOLUTION
STABILIZATION
STAR CLUSTERS
STAR EVOLUTION
Star formation
STARS
ULTRAVIOLET RADIATION
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Summary:Although giant clumps of stars are thought to be crucial to galaxy formation and evolution, the most basic demographics of clumps are still uncertain, mainly because the definition of clumps has not been thoroughly discussed. In this paper, we carry out a study of the basic demographics of clumps in star-forming galaxies at 0.5 < z < 3, using our proposed physical definition that UV-bright clumps are discrete star-forming regions that individually contribute more than 8% of the rest-frame UV light of their galaxies. Clumps defined this way are significantly brighter than the H II regions of nearby large spiral galaxies, either individually or blended, when physical spatial resolution and cosmological dimming are considered. The clump contribution in the intermediate-mass and massive galaxies is possibly linked to the molecular gas fraction of the galaxies. The clump contribution to the SFR of star-forming galaxies, generally around 4%-10%, also shows dependence on the galaxy M, but for a given galaxy M, its dependence on the redshift is mild.
ISSN:1538-4357
0004-637X
1538-4357
DOI:10.1088/0004-637X/800/1/39