The minor role of gas-rich major mergers in the rise of intermediate-mass early types at z ≤ 1



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López Sanjuan, Carlos and Balcells, Marc and Pérez González, Pablo Guillermo and Barro, Guillermo and García Dabó, César Enrique and Gallego Maestro, Jesús and Zamorano Calvo, Jaime (2010) The minor role of gas-rich major mergers in the rise of intermediate-mass early types at z ≤ 1. Astrophysical journal, 710 (2). pp. 1170-1178. ISSN 0004-637X

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We study the evolution of galaxy structure since z ~ 1 to the present. From a Great Observatories Origins Deep Survey South (GOODS-S) multi-band catalog, we define (blue) luminosity- and mass-weighted samples, limited by MB ≤ –20 and M sstarf ≥ 1010 M ☉, comprising 1122 and 987 galaxies, respectively. We extract early-type (ET; E/S0/Sa) and late-type (LT; Sb-Irr) subsamples by their position in the concentration-asymmetry plane, in which galaxies exhibit a clear bimodality. We find that the ET fraction, f ET, rises with cosmic time, with a corresponding decrease in the LT fraction, f LT, in both luminosity- and mass-selected samples. However, the evolution of the comoving number density is very different: the decrease in the total number density of MB ≤ –20 galaxies since z = 1 is due to the decrease in the LT population, which accounts for ~75% of the total star formation rate in the range under study, while the increase in the total number density of M sstarf ≥ 1010 M ☉ galaxies in the same redshift range is due to the evolution of ETs. This suggests that we need a structural transformation between LT galaxies that form stars actively and ET galaxies in which the stellar mass is located. Comparing the observed evolution with the gas-rich major merger rate in GOODS-S, we infer that only ~20% of the new ET galaxies with M sstarf ≥ 1010 M ☉ appeared since z ~ 1 can be explained by this kind of mergers, suggesting that minor mergers and secular processes may be the driving mechanisms of the structural evolution of intermediate-mass (M sstarf ~ 4 × 1010 M ☉) galaxies since z ~ 1.

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© 2010. The American Astronomical Society. This work was supported by the Spanish Programa Nacional de Astronomía y Astrofísica through the project numbers AYA2006-12955, AYA2006-02358, and AYA 2006-15698-C02-02. This work was partially funded by the Spanish MEC under the Consolider-Ingenio 2010 Program grant CSD2006-00070: First Science with the GTC ( work is based on HST/ACS images from GOODS HST Treasury Program, which is supported by NASA through grants HST-GO-09425.01-A and HST-GO-09583.01, and in part on observations made with the Spitzer Space Telescope, which is operated by the Jet Propulsion Laboratory, Caltech under NASA contract 1407.P. G. P. G. acknowledges support from the Ramón y Cajal Program financed by the Spanish Government and the European Union.

Uncontrolled Keywords:VLT-deep-survey; Star-forming galaxies; Digital sky survey; High-redshift galaxies; Extended groth strip; Stellar mass; Elliptic galaxies; Luminosity function; Morphological classification; Assembly history
Subjects:Sciences > Physics > Astrophysics
Sciences > Physics > Astronomy
ID Code:33916
Deposited On:03 Nov 2015 17:27
Last Modified:10 Dec 2018 15:05

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