Evidence for the hierarchical formation of the galactic spheroid

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dc.creator West, Michael J.
dc.creator Cote, Patrick
dc.creator Marzke, Ronald O.
dc.creator Minniti, Dante
dc.date.accessioned 2015-02-10T18:31:51Z
dc.date.available 2015-02-10T18:31:51Z
dc.date.issued 2000-04
dc.identifier.issn 0004-637X
dc.identifier.issn 1538-4357
dc.identifier.uri http://library2.smu.ca/xmlui/handle/01/25953
dc.description Publisher's version/PDF en_CA
dc.description.abstract The possibility that the Galactic spheroid was assembled from isolated, chemically distinct proto-Galactic fragments is investigated using a Monte Carlo technique designed to simulate the chemical evolution of the Galaxy in hierarchical formation scenarios which involve no gas dissipation. By comparing the observed and simulated metallicity distributions of Galactic globular clusters and halo field stars, we estimate the level of fragmentation in the collapsing proto-Galaxy. Although the formation process is highly stochastic, the simulations frequently show good agreement with the observed metallicity distributions, provided the luminosity function of proto-Galactic fragments had the form dN [alpha] L[superscript alpha] dL , where [alpha] ~ -2. While this steep slope is strongly at odds with the presently observed luminosity function of the Local Group, it is in close agreement with the predictions of semianalytic and numerical models of hierarchical galaxy formation. We discuss a number of possible explanations for this discrepancy. These simulations suggest that the Galactic halo and its globular cluster system were assembled via the accretion and disruption of ~ 10[superscript 3] metal-poor, proto-Galactic fragments by the dominant building block: a protobulge whose own metal-rich globular clusters system has been preferentially eroded by dynamical processes. This formation scenario may provide a simple explanation for the different shapes of the Galactic globular cluster and halo star metallicity distributions. Based on the similar properties of globular clusters belonging to spiral and giant elliptical galaxies, we argue that the same process (e.g., hierarchical growth involving little gas dissipation) is responsible for the formation of both giant elliptical galaxies and the bulge-halo components of spiral galaxies. en_CA
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dc.description.provenance Made available in DSpace on 2015-02-10T18:31:51Z (GMT). No. of bitstreams: 1 West_Michael_J_article_2000.pdf: 1602256 bytes, checksum: b2d65da3fbb690716680d395648dabf5 (MD5) Previous issue date: 2000-04 en
dc.language.iso en en_CA
dc.publisher American Astronomical Society en_CA
dc.relation.uri http://dx.doi.org/10.1086/308709
dc.rights Article is made available in accordance with the publisher’s policy and is subject to copyright law. Please refer to the publisher’s site. Any re-use of this article is to be in accordance with the publisher’s copyright policy. This posting is in no way granting any permission for re-use to the reader/user.
dc.subject.lcsh Galactic halos
dc.subject.lcsh Spiral galaxies
dc.subject.lcsh Milky Way
dc.subject.lcsh Galaxies -- Evolution
dc.title Evidence for the hierarchical formation of the galactic spheroid en_CA
dc.type Text en_CA
dcterms.bibliographicCitation Astrophysical Journal 533(2), 869-883. (2000) en_CA
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Article is made available in accordance with the publisher’s policy and is subject to copyright law. Please refer to the publisher’s site. Any re-use of this article is to be in accordance with the publisher’s copyright policy. This posting is in no way granting any permission for re-use to the reader/user.
 
Published Version: http://dx.doi.org/10.1086/308709
 
 

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