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Paper: Strong Size Evolution of the Most Massive Galaxies since z ∼ 2
Volume: 390, Pathways Through an Eclectic Universe
Page: 416
Authors: Trujillo, I.; Conselice, C.J.
Abstract: We explore the size evolution of 831 very massive galaxies (M ≥ 1011 h−270 M) since z ∼ 2 using the combined capabilities of the large near infrared Palomar/DEEP-2 survey, and the superb resolution of the HST ACS camera. We split our sample according to their light concentration using the Sérsic index n. At a given stellar mass, both low (n < 2.5) and highly (n > 2.5) concentrated objects were much smaller in the past than their local massive counterparts. The evolution is particularly strong for the highly concentrated (spheroid-like) objects. At z ∼ 1.5, massive spheroid-like objects were a factor of 4(±0.4) smaller (i.e., almost two orders of magnitude denser) than those we see today. These small sized, high mass galaxies do not exist in the nearby Universe, suggesting that this population merged with other galaxies over several billion years to form the largest galaxies we see today
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