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          Institute: MPI für Astronomie     Collection: Publikationen_mpia     Display Documents

ID: 421673.0, MPI für Astronomie / Publikationen_mpia
An N-body/SPH study of isolated galaxy mass density profiles
Authors:Foyle, Kelly; Courteau, Stéphane; Thacker, Robert J.
Date of Publication (YYYY-MM-DD):2008
Title of Journal:Monthly Notices of the Royal Astronomical Society
Journal Abbrev.:MNRAS
Start Page:1821
End Page:1844
Review Status:Peer-review
Audience:Experts Only
Abstract / Description:We investigate the evolution of mass density profiles in secular disc galaxy models, paying special attention to the development of a two-component profile from a single initial exponential disc free of cosmological evolution (i.e. no accretion or interactions). As the source of density profile variations, we examine the parameter space of the spin parameter, halo concentration, virial mass, disc mass and bulge mass, for a total of 162 simulations in the context of a plausible model of star formation and feedback. The isolated galaxy models are based on the method of Springel & White and were evolved using the N-body/SPH code GADGET-2. The initially pure exponential discs have a minimum of 1.4 million particles and most models were evolved over a period of 10 Gyr. We find that the slope of the outer density profile is in close agreement with that of the initial profile and remains stable over time, whereas the inner density profile slope evolves considerably as a result of angular momentum redistribution. The evolution of the galaxy mass density profile, including the development of a two-component profile with an inner and outer segment, is controlled by the ratio of the disc mass fraction, md, to the halo spin parameter, lambda. The location of the break between the two components and speed at which it develops is directly proportional to md/lambda the amplitude of the transition between the inner and outer regions is however controlled by the ratio of halo concentration to virial velocity. The location of the divide between the inner and outer profile does not change with time. The condition for a two-component profile is roughly md/lambda >= 1. While the development of a two-component density profile is coupled to bar formation, not all barred galaxies develop a two-component profile. A galaxy model showing a clear minimum Toomre Q, normally linked to a double exponential in the stellar profile, may never exhibit any two-component feature thus yielding a fully evolved pure exponential disc.
Free Keywords:methods: numerical; galaxies: kinematics and dynamics; galaxies: spiral
External Publication Status:published
Document Type:Article
Communicated by:N. N.
Affiliations:MPI für Astronomie
Identifiers:URL:http://adsabs.harvard.edu/abs/2008MNRAS.386.1821F [ID No:1]
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