Multiple kinetic k-essence, phantom barrier crossing and stability

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dc.contributor.authorSur, Sourav
dc.contributor.authorDas, Saurya
dc.date.accessioned2015-12-15T19:20:49Z
dc.date.available2015-12-15T19:20:49Z
dc.date.issued2015-12-15
dc.descriptionSherpa Romeo green journal. “This is an author-created, un-copyedited version of an article accepted for publication/published in Journal of Cosmology and Astroparticle Physics. IOP Publishing Ltd is not responsible for any errors or omissions in this version of the manuscript or any version derived from it.”en_US
dc.description.abstractWe investigate models of dark energy with purely kinetic multiple k- essence sources that allow for the crossing of the phantom divide line, without violating the conditions of stability. It is known that with more than one kinetic k-field one can possibly construct dark energy models whose equation of state parameter wX crosses −1 (the phantom barrier) at recent red-shifts, as indicated by the Supernova Ia and other observational probes. However, such models may suffer from cosmological instabilities, as the effective speed of propagation cX of the dark energy density perturbations may become imaginary while the wX = −1 barrier is crossed. Working out the expression for cX we show that multiple kinetic k-essence fields do indeed lead to a wX = −1 crossing dark energy model, satisfying the stability criterion c2 X ≥ 0 as well as the condition cX ≤ 1 (in natural units), which implies that the dark energy is not super-luminal. As a specific example, we construct a phantom barrier crossing model involving three k-fields for which cX is a constant, lying between 0 and 1. The model fits well with the latest Supernova Ia Union data, and the best fit shows that wX crosses −1 at red-shift z ∼ 0.2, whereas the dark energy density nearly tracks the matter density at higher red-shifts.en_US
dc.description.peer-reviewNo
dc.identifier.citationSur, S., & Das, S. (2009). Multiple kinetic k-essence, phantom barrier crossing and stability. Journal of Cosmology and Astroparticle Physics, 2009(01), 007. https://doi.org/10.1088/1475-7516/2009/01/007
dc.identifier.urihttps://hdl.handle.net/10133/3829
dc.language.isoen_CAen_US
dc.publisher.departmentDepartment of Physicsen_US
dc.publisher.facultyArts and Scienceen_US
dc.publisher.institutionUniversity of Lethbridgeen_US
dc.publisher.urlhttps://doi.org/10.1088/1475-7516/2009/01/007
dc.subjectDark energyen_US
dc.subjectKinetic k-essenceen_US
dc.subjectPhantom barrieren_US
dc.subjectStabilityen_US
dc.subjectDark energy theory
dc.subjectSupernova type Ia
dc.subjectCosmological perturbation theory
dc.titleMultiple kinetic k-essence, phantom barrier crossing and stabilityen_US
dc.typeArticleen_US
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