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Article: Can dark matter be a BoseEinstein condensate?
Title  Can dark matter be a BoseEinstein condensate? 

Authors  
Keywords  Dark Matter Dark Matter Simulations 
Issue Date  2007 
Publisher  Institute of Physics Publishing. The Journal's web site is located at http://www.iop.org/EJ/journal/JCAP 
Citation  Journal of Cosmology and Astroparticle Physics, 2007 n. 6 How to Cite? 
Abstract  We consider the possibility that the dark matter which is required to explain the dynamics of the neutral hydrogen clouds at large distances from the galactic centre could be in the form of a BoseEinstein condensate. To study the condensate we use the nonrelativistic GrossPitaevskii equation. By introducing the Madelung representation of the wavefunction, we formulate the dynamics of the system in terms of the continuity equation and of the hydrodynamic Euler equations. Hence dark matter can be described as a nonrelativistic, Newtonian BoseEinstein gravitational condensate gas, whose density and pressure are related by a barotropic equation of state. In the case of a condensate with quartic nonlinearity, the equation of state is polytropic with index n ≤ 1. In the framework of the ThomasFermi approximation the structure of the Newtonian gravitational condensate is described by the LaneEmden equation, which can be exactly solved. General relativistic configurations with quartic nonlinearity are studied, by numerically integrating the structure equations. The basic parameters (mass and radius) of the BoseEinstein condensate dark matter halos sensitively depend on the mass of the condensed particle and of the scattering length. To test the validity of the model we fit the Newtonian tangential velocity equation of the model with a sample of rotation curves of low surface brightness and dwarf galaxies, respectively. We find a very good agreement between the theoretical rotation curves and the observational data for the low surface brightness galaxies. The deflection of photons passing through the dark matter halos is also analysed, and the bending angle of light is computed. The bending angle obtained for the BoseEinstein condensate is larger than that predicted by standard general relativistic and dark matter models. The angular radii of the Einstein rings are obtained in the small angle approximation. Therefore the study of the light deflection by galaxies and the gravitational lensing could discriminate between the BoseEinstein condensate dark matter model and other dark matter models. © IOP Publishing Ltd. 
Persistent Identifier  http://hdl.handle.net/10722/91826 
ISSN  2015 Impact Factor: 5.634 2015 SCImago Journal Rankings: 0.652 
ISI Accession Number ID  
References 
DC Field  Value  Language 

dc.contributor.author  Böhmer, CG  en_HK 
dc.contributor.author  Harko, T  en_HK 
dc.date.accessioned  20100917T10:27:45Z   
dc.date.available  20100917T10:27:45Z   
dc.date.issued  2007  en_HK 
dc.identifier.citation  Journal of Cosmology and Astroparticle Physics, 2007 n. 6  en_HK 
dc.identifier.issn  14757516  en_HK 
dc.identifier.uri  http://hdl.handle.net/10722/91826   
dc.description.abstract  We consider the possibility that the dark matter which is required to explain the dynamics of the neutral hydrogen clouds at large distances from the galactic centre could be in the form of a BoseEinstein condensate. To study the condensate we use the nonrelativistic GrossPitaevskii equation. By introducing the Madelung representation of the wavefunction, we formulate the dynamics of the system in terms of the continuity equation and of the hydrodynamic Euler equations. Hence dark matter can be described as a nonrelativistic, Newtonian BoseEinstein gravitational condensate gas, whose density and pressure are related by a barotropic equation of state. In the case of a condensate with quartic nonlinearity, the equation of state is polytropic with index n ≤ 1. In the framework of the ThomasFermi approximation the structure of the Newtonian gravitational condensate is described by the LaneEmden equation, which can be exactly solved. General relativistic configurations with quartic nonlinearity are studied, by numerically integrating the structure equations. The basic parameters (mass and radius) of the BoseEinstein condensate dark matter halos sensitively depend on the mass of the condensed particle and of the scattering length. To test the validity of the model we fit the Newtonian tangential velocity equation of the model with a sample of rotation curves of low surface brightness and dwarf galaxies, respectively. We find a very good agreement between the theoretical rotation curves and the observational data for the low surface brightness galaxies. The deflection of photons passing through the dark matter halos is also analysed, and the bending angle of light is computed. The bending angle obtained for the BoseEinstein condensate is larger than that predicted by standard general relativistic and dark matter models. The angular radii of the Einstein rings are obtained in the small angle approximation. Therefore the study of the light deflection by galaxies and the gravitational lensing could discriminate between the BoseEinstein condensate dark matter model and other dark matter models. © IOP Publishing Ltd.  en_HK 
dc.language  eng  en_HK 
dc.publisher  Institute of Physics Publishing. The Journal's web site is located at http://www.iop.org/EJ/journal/JCAP  en_HK 
dc.relation.ispartof  Journal of Cosmology and Astroparticle Physics  en_HK 
dc.subject  Dark Matter  en_HK 
dc.subject  Dark Matter Simulations  en_HK 
dc.title  Can dark matter be a BoseEinstein condensate?  en_HK 
dc.type  Article  en_HK 
dc.identifier.email  Harko, TC:harko@hkucc.hku.hk  en_HK 
dc.identifier.authority  Harko, TC=rp1333  en_HK 
dc.description.nature  link_to_subscribed_fulltext   
dc.identifier.doi  10.1088/14757516/2007/06/025  en_HK 
dc.identifier.scopus  eid_2s2.034548623343  en_HK 
dc.relation.references  http://www.scopus.com/mlt/select.url?eid=2s2.034548623343&selection=ref&src=s&origin=recordpage  en_HK 
dc.identifier.issue  6  en_HK 
dc.identifier.isi  WOS:000247924600005   
dc.identifier.citeulike  1407844   