On the Transition of the Galaxy Quenching Mode at 0.5 < z < 1 in CANDELS

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We investigate the galaxy quenching process at intermediate redshift using a sample of similar to 4400 galaxies with M-* >10(9) M-circle dot between redshift 0.5 and 1.0 in all five CANDELS fields. We divide this sample, using the integrated specific star formation rate (sSFR), into four subgroups: star-forming galaxies (SFGs) above and below the ridge of the star-forming main sequence (SFMS), transition galaxies and quiescent galaxies. We study their UVI (U -V versus V-I) color gradients to infer their sSFR gradients out to twice effective radii. We show that on average both star-forming and transition galaxies at all masses are not fully quenched at any radii, whereas quiescent galaxies are fully quenched at all radii. We find that at low masses (M-* = 10(9) - 10(10) M-circle dot) SFGs both above and below the SFMS ridge generally have flat sSFR profiles, whereas the transition galaxies at the same masses generally have sSFRs that are more suppressed in their outskirts. In contrast, at high masses (M-* > 10(10.5) M-circle dot), SFGs above and below the SFMS ridge and transition galaxies generally have varying degrees of more centrally suppressed sSFRs relative to their outskirts. These findings indicate that at z similar to 0.5-1.0 the main galaxy quenching mode depends on its already formed stellar mass, exhibiting a transition from "the outside-in" at M*<= 10(10) M-circle dot to "the inside-out" at M-* > 10(10.5) M-circle dot. In other words, our findings support that internal processes dominate the quenching of massive galaxies, whereas external processes dominate the quenching of low-mass galaxies.
© 2018. The American Astronomical Society. All rights reserved. Artículo firmado por 22 autores. We acknowledge the anonymous referee for constructive comments and suggestions that significantly improved this paper. We thank Steven Willner for helpful comments on the manuscript, and Shude Mao for useful discussion. We acknowledge support from the NSF grants of China (11573017,11733006) and the CANDELS program HST-GO-12060 by NASA through a grant from the STScI. Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Incorporated, under NASA contract NAS5-26555. This work is partly based on observations taken by the 3D-HST Treasury Program (GO 12177 and 12328) with the NASA/ESA HST, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555. S.M.F., D.C.K., Y.G., and H.M.Y. acknowledge partial support from US NSF grant AST-16-15730. P.G.P.-G. acknowledges support from Spanish Government MINECO AYA2015-70815-ERC and AYA2015-63650-P Grants.
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