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

• Published in: The Astrophysical journal Vol. 800; no. 1; pp. 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: Journal Article
• Language: English
• Published: United States 10.02.2015
• 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
• ISSN: 1538-4357; 0004-637X; 1538-4357
• DOI: 10.1088/0004-637X/800/1/39

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.