Crossing the phantom divide without phantom matter
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چکیده
منابع مشابه
Crossing the phantom divide
We consider fluid perturbations close to the ‘‘phantom divide’’ characterized by p and discuss the conditions under which divergencies in the perturbations can be avoided. We find that the behavior of the perturbations depends crucially on the prescription for the pressure perturbation p. The pressure perturbation is usually defined using the dark energy rest-frame, but we show that this frame ...
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The rôle of the interaction in crossing the phantom divide line in the Chaplygin gas model is discussed. We obtain some general properties of the interactions that allow the model to arrive at phantom divide line. We show that these properties put some conditions on the ratio of dark matter to dark energy density. PACS: 98.80.-k, 98.80.Jk
متن کاملCrossing the Phantom Divide: Dark Energy Internal Degrees of Freedom
Dark energy constraints have forced viable alternatives that differ substantially from a cosmological constant Λ to have an equation of state w that evolves across the phantom divide set by Λ. Naively, crossing this divide makes the dark energy gravitationally unstable, a problem that is typically finessed by unphysically ignoring the perturbations. While this procedure does not affect constrai...
متن کاملCrossing the Phantom Divide with Parameterized Post-Friedmann Dark Energy
Dark energy models with a single scalar field cannot cross the equation of state divide set by a cosmological constant. More general models that allow crossing require additional degrees of freedom to ensure gravitational stability. We show that a parameterized post-Friedmann description of cosmic acceleration provides a simple but accurate description of multiple scalar field crossing models. ...
متن کاملCrossing the phantom divide with parametrized post-Friedmann dark energy
Wenjuan Fang, Wayne Hu, and Antony Lewis Department of Physics, Columbia University, New York, New York 10027, USA Kavli Institute for Cosmological Physics, Department of Astronomy & Astrophysics, Enrico Fermi Institute, University of Chicago, Chicago, Illinois 60637, USA Institute of Astronomy, Madingley Road, Cambridge, CB3 0HA, United Kingdom (Received 22 August 2008; published 24 October 2008)
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ژورنال
عنوان ژورنال: Journal of Cosmology and Astroparticle Physics
سال: 2006
ISSN: 1475-7516
DOI: 10.1088/1475-7516/2006/09/004