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Paper: SEDs and NIR Morphologies of Old and Dusty Galaxies at z2
Volume: 446, Galaxy Evolution: Infrared to Millimeter Wavelength Perspective
Page: 303
Authors: Wang, T.; Huang, J.; Wuyts, S.; Fang, G.; Fazio, G.; Chen, Z.; Kong, X.; Gu, Q.
Abstract: We explore the nature of the IRAC-selected Extremely Red Objects (IEROs; z′ – [3.6] > 3.25 and [3.6] < 21.5) using the most extensive data set in GOODS-South. The majority of these IEROs are proved to be at 1.4 < z < 2.5 with typical stellar mass of ∼ 1011Mmsol. In particular, we show that they dominate the high-mass end of the stellar mass function, and contribute ∼ 90% of all the most massive (M* > 1 × 1011M) galaxies at the redshift interval. We show these galaxies can be cleanly separated into old and dusty galaxies using simple H – [8.0] color: the old galaxies primarily have H – [8.0] < 1.2 and the dusty galaxies are much redder. Such a classification scheme is further shown to be broadly consistent with that using MIPS 24 μm, rest-frame UV and VJ color and SSP fitting. In addition, with new NIR imaging from HST/WFC3 we show that these massive old and dusty galaxies exhibit distinct morphologies: the old galaxies are primarily compact and spheroidal whereas the dusty galaxies show more extended and disturbed morphologies. With the clean and consistent separation between old and dusty galaxies, we derive the fraction of quiescent massive galaxies to be ∼ 25%, which is the same if we only take the most massive galaxies into account.
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