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Article: Galactic rotation curves in modified gravity with nonminimal coupling between matter and geometry

TitleGalactic rotation curves in modified gravity with nonminimal coupling between matter and geometry
Authors
Issue Date2010
PublisherAmerican Physical Society. The Journal's web site is located at http://prd.aps.org
Citation
Physical Review D - Particles, Fields, Gravitation and Cosmology, 2010, v. 81 n. 8, article no. 084050 How to Cite?
AbstractWe investigate the possibility that the behavior of the rotational velocities of test particles gravitating around galaxies can be explained in the framework of modified gravity models with nonminimal matter-geometry coupling. Generally, the dynamics of test particles around galaxies, as well as the corresponding mass deficit, is explained by postulating the existence of dark matter. The extra terms in the gravitational field equations with geometry-matter coupling modify the equations of motion of test particles and induce a supplementary gravitational interaction. Starting from the variational principle describing the particle motion in the presence of the nonminimal coupling, the expression of the tangential velocity of a test particle, moving in the vacuum on a stable circular orbit in a spherically symmetric geometry, is derived. The tangential velocity depends on the metric tensor components, as well as on the coupling function between matter and geometry. The Doppler velocity shifts are also obtained in terms of the coupling function. If the tangential velocity profile is known, the coupling term between matter and geometry can be obtained explicitly in an analytical form. The functional form of this function is obtained in two cases, for a constant tangential velocity and for an empirical velocity profile obtained from astronomical observations, respectively. All the physical and geometrical quantities in the modified gravity model with nonminimal coupling between matter and geometry can be expressed in terms of observable/measurable parameters, like the tangential velocity, the baryonic mass of the galaxy, and the Doppler frequency shifts. Therefore, these results open the possibility of directly testing the modified gravity models with nonminimal coupling between matter and geometry by using direct astronomical and astrophysical observations at the galactic or extragalactic scale. © 2010 The American Physical Society.
Persistent Identifierhttp://hdl.handle.net/10722/91777
ISSN
2014 Impact Factor: 4.643
2015 SCImago Journal Rankings: 1.882
ISI Accession Number ID
Funding AgencyGrant Number
government of the Hong Kong SAR
Funding Information:

This work is supported by an RGC grant of the government of the Hong Kong SAR.

References

 

DC FieldValueLanguage
dc.contributor.authorHarko, Ten_HK
dc.date.accessioned2010-09-17T10:26:19Z-
dc.date.available2010-09-17T10:26:19Z-
dc.date.issued2010en_HK
dc.identifier.citationPhysical Review D - Particles, Fields, Gravitation and Cosmology, 2010, v. 81 n. 8, article no. 084050en_HK
dc.identifier.issn1550-7998en_HK
dc.identifier.urihttp://hdl.handle.net/10722/91777-
dc.description.abstractWe investigate the possibility that the behavior of the rotational velocities of test particles gravitating around galaxies can be explained in the framework of modified gravity models with nonminimal matter-geometry coupling. Generally, the dynamics of test particles around galaxies, as well as the corresponding mass deficit, is explained by postulating the existence of dark matter. The extra terms in the gravitational field equations with geometry-matter coupling modify the equations of motion of test particles and induce a supplementary gravitational interaction. Starting from the variational principle describing the particle motion in the presence of the nonminimal coupling, the expression of the tangential velocity of a test particle, moving in the vacuum on a stable circular orbit in a spherically symmetric geometry, is derived. The tangential velocity depends on the metric tensor components, as well as on the coupling function between matter and geometry. The Doppler velocity shifts are also obtained in terms of the coupling function. If the tangential velocity profile is known, the coupling term between matter and geometry can be obtained explicitly in an analytical form. The functional form of this function is obtained in two cases, for a constant tangential velocity and for an empirical velocity profile obtained from astronomical observations, respectively. All the physical and geometrical quantities in the modified gravity model with nonminimal coupling between matter and geometry can be expressed in terms of observable/measurable parameters, like the tangential velocity, the baryonic mass of the galaxy, and the Doppler frequency shifts. Therefore, these results open the possibility of directly testing the modified gravity models with nonminimal coupling between matter and geometry by using direct astronomical and astrophysical observations at the galactic or extragalactic scale. © 2010 The American Physical Society.en_HK
dc.languageengen_HK
dc.publisherAmerican Physical Society. The Journal's web site is located at http://prd.aps.orgen_HK
dc.relation.ispartofPhysical Review D - Particles, Fields, Gravitation and Cosmologyen_HK
dc.rightsPhysical Review D (Particles, Fields, Gravitation and Cosmology). Copyright © American Physical Society-
dc.rightsCreative Commons: Attribution 3.0 Hong Kong License-
dc.titleGalactic rotation curves in modified gravity with nonminimal coupling between matter and geometryen_HK
dc.typeArticleen_HK
dc.identifier.emailHarko, TC:harko@hkucc.hku.hken_HK
dc.identifier.authorityHarko, TC=rp1333en_HK
dc.description.naturepublished_or_final_version-
dc.identifier.doi10.1103/PhysRevD.81.084050en_HK
dc.identifier.scopuseid_2-s2.0-77952506278en_HK
dc.identifier.hkuros242350-
dc.relation.referenceshttp://www.scopus.com/mlt/select.url?eid=2-s2.0-77952506278&selection=ref&src=s&origin=recordpageen_HK
dc.identifier.volume81en_HK
dc.identifier.issue8en_HK
dc.identifier.eissn1550-2368-
dc.identifier.isiWOS:000277205000105-

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