The DEEP2 Galaxy Redshift Survey: Environments of Poststarburst Galaxies at z~0.1 and z~0.8 - AstrophysicsReportar como inadecuado

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Abstract: Postststarburst K+A galaxies are candidates for galaxies in transition froma star-forming phase to a passively-evolving phase. We have spectroscopicallyidentified large samples of K+A galaxies both in the SDSS at z~0.1 and in theDEEP2 survey at z~0.8, using a robust selection method based on a cut in Hbetaemission rather than the more problematic OII 3727. Based on measurements ofthe overdensity of galaxies around each object, we find that K+A galaxiesbrighter than 0.4L* B at low-z have a similar, statistically indistinguishableenvironment distribution as blue galaxies, preferring underdense environments,but dramatically different from that of red galaxies. However, at higher-z, theenvironment distribution of K+A galaxies is more similar to red galaxies thanto blue galaxies. We conclude that the quenching of star formation and thebuild-up of the red sequence through the K+A phase is happening in relativelyoverdense environments at z~1 but in relatively underdense environments at z~0.Although the relative environments where quenching occurs are decreasing withtime, the corresponding absolute environment may have stayed the same alongwith the quenching mechanisms, because the mean absolute environments of allgalaxies has to grow with time. In addition, we do not find any significantdependence on luminosity in the environment distribution of K+As. The existenceof a large K+A population in the field at both redshifts indicates thatcluster-specific mechanisms cannot be the dominant route by which thesegalaxies are formed. We also demonstrates that studying K+A-environmentrelations by measuring the K+A fraction in different environments is highlynon-robust. Statistical comparisons of the overall environment distributions ofdifferent populations are much better behaved.

Autor: Renbin Yan, Jeffrey A. Newman, S.M. Faber, Alison L. Coil, Michael C. Cooper, Marc Davis, Benjamin J. Weiner, Brian F. Gerke, Dav


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