# Indiana University

 dc.contributor.author Cheung, E. en dc.contributor.author Faber, S.M. en dc.contributor.author Koo, D.C. en dc.contributor.author Dutton, A.A. en dc.contributor.author Simard, L. en dc.contributor.author McGrath, E.J. en dc.contributor.author Huang, J.-S. en dc.contributor.author Bell, E.F. en dc.contributor.author Dekel, A. en dc.contributor.author Fang, J.J. en dc.contributor.author Salim, S. en dc.contributor.author Barro, G. en dc.contributor.author Bundy, K. en dc.contributor.author Coil, A.L. en dc.contributor.author Cooper, M.C. en dc.contributor.author Conselice, C.J. en dc.contributor.author Davis, M. en dc.contributor.author Domínguez, A. en dc.contributor.author Kassin, S.A. en dc.contributor.author Kocevski, D.D. en dc.contributor.author Koekemoer, A.M. en dc.contributor.author Lin, L. en dc.contributor.author Lotz, J.M. en dc.contributor.author Newman, J.a. en dc.contributor.author Phillips, A.C. en dc.contributor.author Rosario, D.J. en dc.contributor.author Weiner, B.J. en dc.contributor.author Willmer, C.N.A. en dc.date.accessioned 2014-11-03T19:58:37Z en dc.date.available 2014-11-03T19:58:37Z en dc.date.issued 2012 en dc.identifier.citation Cheung, E., Faber, S. M., Koo, D. C., Dutton, A. A., Simard, L., McGrath, E. J., . . . Willmer, C. N. A. (2012). The dependence of quenching upon the inner structure of galaxies at 0.5 ≤ $z$ < 0.8 in the DEEP2/AEGIS survey. Astrophysical Journal, 760(2), 131. http://dx.doi.org/10.1088/0004-637X/760/2/131 en dc.identifier.uri http://hdl.handle.net/2022/19109 dc.description.abstract The shutdown of star formation in galaxies is generally termed "quenching." Quenching may occur through a variety of processes, e.g., active galactic nucleus (AGN) feedback, stellar feedback, or the shock heating of gas in the dark matter halo. However, which mechanism(s) is, in fact, responsible for quenching is still in question. This paper addresses quenching by searching for traces of possible quenching processes through their effects on galaxy structural parameters such as stellar mass ($M_{\ast }$), $M_{\ast }/r_{e}$, surface stellar mass density ($\sim M_{\ast }/r^{2}_{e}$), and Sérsic index ($n$). We analyze the rest-frame $U - B$ color correlations versus these structural parameters using a sample of galaxies in the redshift range $0.5 \lesssim z < 0.8$ from the DEEP2/AEGIS survey. In addition to global radii, stellar masses, and Sérsic parameters, we also use "bulge" and "disk" photometric measurements from GIM2D fits to $\textit{HST/ACS V}$ and $I$ images. We assess the tightness of the color relationships by measuring their "overlap regions," defined as the area in color-parameter space in which red and blue galaxies overlap; the parameter that minimizes these overlap regions is considered to be the most effective color discriminator. We find that Sérsic index ($n$) has the smallest overlap region among all tested parameters and resembles a step function with a threshold value of $n$ = 2.3. There exists, however, a significant population of outliers with blue colors yet high n values that seem to contradict this behavior; they make up $\approx$ 40% of $n$ > 2.3 galaxies. We hypothesize that their Sérsic values may be distorted by bursts of star formation, AGNs, and/or poor fits, leading us to consider central surface stellar mass density, $\sum^{\ast }_{1 \:\text{kpc}}$, as an alternative to Sérsic index. Not only does $\sum^{\ast }_{1 \:\text{kpc}}$ correct the outliers, but it also forms a tight relationship with color, suggesting that the $\textit{innermost structure of galaxies is most physically linked with quenching}$. Furthermore, at $z \sim 0.65$, the majority of the blue cloud galaxies cannot simply fade onto the red sequence since their GIM2D bulge masses are only half as large on average as the bulge masses of similar red sequence galaxies, thus demonstrating that stellar mass must absolutely increase at the centers of galaxies as they quench. We discuss a two-stage model for quenching in which galaxy star formation rates are controlled by their dark halos while they are still in the blue cloud and a second quenching process sets in later, associated with the central stellar mass buildup. The mass buildup is naturally explained by any non-axisymmetric features in the potential, such as those induced by mergers and/or disk instabilities. However, the identity of the second quenching agent is still unknown. We have placed our data catalog online en dc.language.iso en_US en dc.publisher The American Astronomical Society en dc.relation.isversionof https://doi.org/10.1088/0004-637X/760/2/131 en dc.rights © 2012 The American Astronomical Society en dc.subject galaxies: bulges en dc.subject galaxies: evolution en dc.subject galaxies: formation en dc.subject galaxies: fundamental parameters en dc.subject galaxies: structure en dc.title The dependence of quenching upon the inner structure of galaxies at 0.5 ≤ $z$ < 0.8 in the DEEP2/AEGIS survey en dc.type Article en dc.altmetrics.display false en
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