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Paper: Spatially Resolved Color-Magnitude Relation and Morphology of z ∼ 1 ULIRGs
Volume: 477, Galaxy Mergers in an Evolving Universe
Page: 203
Authors: Yun, M. S.; Chen, Y.; Lowenthal, J. D.
Abstract: We present an analysis of the color-magnitude relations and quantitative morphological parameters of a sample of 54 z ∼ 0 ULIRGs and nine z ∼ 1 ULIRGs. Both populations show surprisingly blue color and high luminosity in the rest-frame optical bands, supporting their association with massive stellar hosts whose optical light is dominated by spatially extended young stellar clusters that formed during the ongoing merger. We infer an age of 200-500 Myr for the stellar population dominating the rest frame optical light. Many of these ULIRGs have the quantitative morphological parameters characteristic of merger systems, but these parameters should be interpreted with care. We introduce a spatially resolved color-magnitude analysis using a pixel-by-pixel color-magnitude diagram (pCMD). Our population synthesis modeling suggests that the brightest regions of the z ∼ 1 ULIRGs require ages between 10 and 500 Myr and a stellar surface mass density an order of magnitude higher than that of the inner Milky Way.
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