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dc.contributor.authorThomas, D.
dc.contributor.authorMaraston, C.
dc.contributor.authorSchawinski, K.
dc.contributor.authorSarzi, M.
dc.contributor.authorSilk, J.
dc.date.accessioned2010-11-30T14:27:58Z
dc.date.available2010-11-30T14:27:58Z
dc.date.issued2010
dc.identifier.citationThomas , D , Maraston , C , Schawinski , K , Sarzi , M & Silk , J 2010 , ' Environment and self-regulation in galaxy formation ' , Monthly Notices of the Royal Astronomical Society , vol. 404 , no. 4 , pp. 1775-1789 . https://doi.org/10.1111/j.1365-2966.2010.16427.x
dc.identifier.issn0035-8711
dc.identifier.otherPURE: 138121
dc.identifier.otherPURE UUID: f8f62de7-0374-42c5-b6b4-3570d425e8bf
dc.identifier.otherdspace: 2299/5041
dc.identifier.otherScopus: 77953573887
dc.identifier.urihttp://hdl.handle.net/2299/5041
dc.descriptionThe definitive article can be found at: http://www3.interscience.wiley.com/ Copyright Royal Astronomical Society
dc.description.abstractThe environment is known to affect the formation and evolution of galaxies considerably best visible through the well-known morphology–density relationship. It is less clear, though, whether the environment is equally important at a given galaxy morphology. In this paper, we study the effect of environment on the evolution of early-type galaxies as imprinted in the fossil record by analysing the stellar population properties of 3360 galaxies morphologically selected by visual inspection from the Sloan Digital Sky Survey in a narrow redshift range ( 0.05 ≤z≤ 0.06 ). The morphological selection algorithm is critical, as it does not bias against recent star formation. We find that the distribution of ages is bimodal with a strong peak at old ages and a secondary peak at young ages around ∼2.5 Gyr containing about 10 per cent of the objects. This is an analogue to 'red sequence' and 'blue cloud' identified in galaxy populations usually containing both early- and late-type galaxies. The fraction of the young, rejuvenated galaxies increases with both decreasing galaxy mass and decreasing environmental density up to about 45 per cent, which implies that the impact of environment increases with decreasing galaxy mass. The rejuvenated galaxies have lower α/Fe ratios than the average and most of them show signs of ongoing star formation through their emission line spectra. All objects that host active galactic nuclei in their centres without star formation are part of the red sequence population. We confirm and statistically strengthen earlier results that luminosity weighted ages, metallicities and α/Fe element ratios of the red sequence population correlate well with velocity dispersion and galaxy mass. Most interestingly, however, these scaling relations are not sensitive to environmental densities and are only driven by galaxy mass. We infer that early-type galaxy formation has undergone a phase transition a few billion years ago around z∼ 0.2 . A self-regulated formation phase without environmental dependence has recently been superseded by a rejuvenation phase, in which the environment plays a decisive role possibly through galaxy mergers and interactions.en
dc.language.isoeng
dc.relation.ispartofMonthly Notices of the Royal Astronomical Society
dc.rightsOpen
dc.titleEnvironment and self-regulation in galaxy formationen
dc.contributor.institutionSchool of Physics, Astronomy and Mathematics
dc.contributor.institutionCentre for Astrophysics Research
dc.contributor.institutionScience & Technology Research Institute
dc.description.statusPeer reviewed
dc.relation.schoolSchool of Physics, Astronomy and Mathematics
dcterms.dateAccepted2010
rioxxterms.versionofrecordhttps://doi.org/10.1111/j.1365-2966.2010.16427.x
rioxxterms.typeJournal Article/Review
herts.preservation.rarelyaccessedtrue
herts.rights.accesstypeOpen


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