The Role of Bulge Formation in the Homogenization of Stellar Populations at Z ~ 2 as Revealed by Internal Color Dispersion in CANDELS

Authors

Steven Boada, Texas A&M University
V. Tilvi, Texas A&M University
R. F. Quadri, Texas A&M University
M. Hilton, University of Nottingham, UK
S. Finkelstein, University of Texas - Austin
Yicheng Guo, University of California - Santa Cruz
N. Bond, Goddard Space Flight Center
C. Conselice, University of KwaZulu-Natal, South Africa
A. Dekel, Hebrew University, Israel
H. Ferguson, Space Telescope Science Institute
M. Giavalisco, University of Massachusetts - Amherst
N. A. Grogin, Space Telescope Science Institute
Dale D. Kocevski, University of KentuckyFollow
A. M. Koekemoer, Space Telescope Science Institute
D. C. Koo, University of California - Santa Cruz

Abstract

We use data from the Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey to study how the spatial variation in the stellar populations of galaxies relates to the formation of galaxies at 1.5 < z < 3.5. We use the internal color dispersion (ICD), measured between the rest-frame UV and optical bands, which is sensitive to age (and dust attenuation) variations in stellar populations. The ICD shows a relation with the stellar masses and morphologies of the galaxies. Galaxies with the largest variation in their stellar populations as evidenced by high ICD have disk-dominated morphologies (with Sérsic indexes M/M_⊙) < 11. There is a marked decrease in the ICD as the stellar mass and/or the Sérsic index increases. By studying the relations between the ICD and other galaxy properties including size, total color, star formation rate, and dust attenuation, we conclude that the largest variations in stellar populations occur in galaxies where the light from newly, high star-forming clumps contrasts older stellar disk populations. This phase reaches a peak for galaxies only with a specific stellar mass range, 10 < log(M/M_⊙) < 11, and prior to the formation of a substantial bulge/spheroid. In contrast, galaxies at higher or lower stellar masses and/or higher Sérsic index (n > 2) show reduced ICD values, implying a greater homogeneity of their stellar populations. This indicates that if a galaxy is to have a quiescent bulge along with a star-forming disk, typical of Hubble sequence galaxies, this is most common for stellar masses 10 < log(M/M_⊙) < 11 and when the bulge component remains relatively small (n > 2).

Document Type

Article

Publication Date

4-22-2015

Notes/Citation Information

Published in The Astrophysical Journal, v. 803, no. 2, article 104, p. 1-14.

© 2015. The American Astronomical Society. All rights reserved.

Reproduced by permission of the AAS.

Digital Object Identifier (DOI)

http://dx.doi.org/10.1088/0004-637X/803/2/104

Funding Information

This work is based on observations taken by the CANDELS Multi-Cycle Treasury Program with the NASA/ESA HST, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555. We also make use of partial support from NSF AST-0808133.

Related Content

This work is based on observations taken by the CANDELS Multi-Cycle Treasury Program with the NASA/ESA HST, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555. . . . We utilize the Rainbow Cosmological Surveys Database, which is operated by the Universidad Complutense de Madrid (UCM), partnered with the University of California Observatories at Santa Cruz (UCO/Lick, UCSC).

Repository Citation

Boada, Steven; Tilvi, V.; Quadri, R. F.; Hilton, M.; Finkelstein, S.; Guo, Yicheng; Bond, N.; Conselice, C.; Dekel, A.; Ferguson, H.; Giavalisco, M.; Grogin, N. A.; Kocevski, Dale D.; Koekemoer, A. M.; and Koo, D. C., "The Role of Bulge Formation in the Homogenization of Stellar Populations at Z ~ 2 as Revealed by Internal Color Dispersion in CANDELS" (2015). Physics and Astronomy Faculty Publications. 263.
https://uknowledge.uky.edu/physastron_facpub/263