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Article: Can the galactic rotation curves be explained in brane world models?
Title  Can the galactic rotation curves be explained in brane world models? 

Authors  
Keywords  Physics  nuclear physics 
Issue Date  2004 
Publisher  American Physical Society. The Journal's web site is located at http://prd.aps.org 
Citation  Physical Review D (Particles and Fields), 2004, v. 70 n. 2, p. 024010:112 How to Cite? 
Abstract  We consider solutions with conformal symmetry of the static, spherically symmetric gravitational field equations in the vacuum in the brane world scenario. By assuming that the vector field generating the symmetry is nonstatic, the general solution of the field equations on the brane can be obtained in an exact parametric form, with the conformal factor taken as parameter. As a physical application of the obtained solutions we consider the behavior of the angular velocity of a test particle moving in a stable circular orbit. In this case the tangential velocity can be expressed as a function of the conformal factor and some integration constants only. For a specific range of integration constants, the tangential velocity of the test particle tends, in the limit of large radial distances, to a constant value. This behavior is specific to galactic rotation curves and is explained usually by invoking the hypothesis of dark matter. The limiting value of the angular velocity of the test particle can be obtained as a function of the baryonic mass and radius of the galaxy. The behavior of the dark radiation and dark pressure terms is also considered in detail, and it is shown that they can be expressed in terms of the rotational velocity of a test particle. Hence all the predictions of the present model can be tested observationally. Therefore the existence of the nonlocal effects, generated by the free gravitational field of the bulk in a conformally symmetric brane, may provide an explanation for the dynamics of the neutral hydrogen clouds at large distances from the galactic center. 
Persistent Identifier  http://hdl.handle.net/10722/43427 
ISSN  2004 Impact Factor: 5.156 
ISI Accession Number ID 
DC Field  Value  Language 

dc.contributor.author  Mak, MK  en_HK 
dc.contributor.author  Harko, TC  en_HK 
dc.date.accessioned  20070323T04:45:29Z   
dc.date.available  20070323T04:45:29Z   
dc.date.issued  2004  en_HK 
dc.identifier.citation  Physical Review D (Particles and Fields), 2004, v. 70 n. 2, p. 024010:112  en_HK 
dc.identifier.issn  05562821  en_HK 
dc.identifier.uri  http://hdl.handle.net/10722/43427   
dc.description.abstract  We consider solutions with conformal symmetry of the static, spherically symmetric gravitational field equations in the vacuum in the brane world scenario. By assuming that the vector field generating the symmetry is nonstatic, the general solution of the field equations on the brane can be obtained in an exact parametric form, with the conformal factor taken as parameter. As a physical application of the obtained solutions we consider the behavior of the angular velocity of a test particle moving in a stable circular orbit. In this case the tangential velocity can be expressed as a function of the conformal factor and some integration constants only. For a specific range of integration constants, the tangential velocity of the test particle tends, in the limit of large radial distances, to a constant value. This behavior is specific to galactic rotation curves and is explained usually by invoking the hypothesis of dark matter. The limiting value of the angular velocity of the test particle can be obtained as a function of the baryonic mass and radius of the galaxy. The behavior of the dark radiation and dark pressure terms is also considered in detail, and it is shown that they can be expressed in terms of the rotational velocity of a test particle. Hence all the predictions of the present model can be tested observationally. Therefore the existence of the nonlocal effects, generated by the free gravitational field of the bulk in a conformally symmetric brane, may provide an explanation for the dynamics of the neutral hydrogen clouds at large distances from the galactic center.  en_HK 
dc.format.extent  161383 bytes   
dc.format.extent  122136 bytes   
dc.format.mimetype  application/pdf   
dc.format.mimetype  application/pdf   
dc.language  eng  en_HK 
dc.publisher  American Physical Society. The Journal's web site is located at http://prd.aps.org  en_HK 
dc.rights  Physical Review D (Particles and Fields). Copyright © American Physical Society.  en_HK 
dc.rights  This work is licensed under a Creative Commons AttributionNonCommercialNoDerivatives 4.0 International License.   
dc.subject  Physics  nuclear physics  en_HK 
dc.title  Can the galactic rotation curves be explained in brane world models?  en_HK 
dc.type  Article  en_HK 
dc.identifier.openurl  http://library.hku.hk:4550/resserv?sid=HKU:IR&issn=05562821&volume=70&issue=2&spage=024010:1&epage=12&date=2004&atitle=Can+the+galactic+rotation+curves+be+explained+in+brane+world+models?  en_HK 
dc.description.nature  published_or_final_version  en_HK 
dc.identifier.doi  10.1103/PhysRevD.70.024010  en_HK 
dc.identifier.hkuros  91993   
dc.identifier.isi  WOS:000223233400039   