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[astroph/0604055] Can the BransDicke gravity possibly with $\Lambda $ be a theory of Dark Matter ?

Authors:  Hongsu Kim 
Abstract:  The pure BransDicke (BD) gravity with or without the cosmological constant
$\Lambda $ has been taken as a model theory for the dark matter. Indeed, there
has been a consensus that unless one modifies either standard theory of
gravity, namely, the general relativity or standard model for particle physics,
or both, one can never achieve a satisfying understanding of the phenomena
associated with dark matter and dark energy. Along this line, our dark matter
model in this work can be thought of as an attempt to modify the gravity side
alone in the simplest fashion to achieve the goal. As is wellknown, the
mysterious flattened rotation curves observed for so long in the outer region
of galactic halos have been the primary cause that called for the existence of
dark matter. Among others, therefore, it is demonstrated that our model theory
can successfully predict the emergence of dark matter halolike configuration
in terms of a selfgravitating spacetime solution to the BD field equations and
reproduce the flattened rotation curve in this dark halolike object in terms
of the nontrivial energy density of the BD scalar field which was absent in
the context of general relativity where the Newton's constant is strictly a
``constant'' having no dynamics. 

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Garth Antony Barber
Joined: 19 Jul 2005 Posts: 71 Affiliation: Published independent

Posted: April 05 2006 


An interesting paper, will it go the same way as Cooperstock & Lieu?
Note that as well as explaining the flat galactic rotation curves, it has yet to explain galaxy/cluster lensing of distant quasars, and BB nucleosynthesis and be concordant with WMAP etc.
Garth 

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Ruth Lazkoz
Joined: 02 Jan 2006 Posts: 14 Affiliation: University of the Basque Country

Posted: June 29 2006 


Hi,
I have a question. I understand that the velocity curves are obtained from Doppler shift measurements, which are frame invariant quantities.
Should then this BransDicke explanation of the flatness of the curves lead to the same conclusions both in the Einstein or in the Jordan frame?
Put another way, if one were to present the results of this paper in terms of Doppler shift, then one should not care for what frame has been chosen, right?
Thanks,
Ruth
Garth Antony Barber wrote:  An interesting paper, will it go the same way as Cooperstock & Lieu?
Note that as well as explaining the flat galactic rotation curves, it has yet to explain galaxy/cluster lensing of distant quasars, and BB nucleosynthesis and be concordant with WMAP etc.
Garth 


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