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Particle horizon

About: Particle horizon is a research topic. Over the lifetime, 2096 publications have been published within this topic receiving 69137 citations.


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Journal ArticleDOI
09 Apr 1999-Pramana
TL;DR: In this paper, the authors show that multiply-connected flat and hyperbolic models are consistent with present observations on scales of 1−20 h−1 Gpc as are the corresponding simply connected flat models.
Abstract: Is the Universe (a spatial section thereof) finite or infinite? Knowing the global geometry of a Friedmann-Lemaitre (FL) universe requires knowing both its curvature and its topology. A flat or hyperbolic (‘open’) FL universe is not necessarily infinite in volume. Multiply connected flat and hyperbolic models are, in general, as consistent with present observations on scales of 1–20 h−1 Gpc as are the corresponding simply connected flat and hyperbolic models. The methods of detecting multiply connected models (MCM’s) are presently in their pioneering phase of development and the optimal observationally realistic strategy is probably yet to be calculated. Constraints against MCM’s on ∼1–4 h−1 Gpc scales have been claimed, but relate more to inconsistent assumptions on perturbation statistics rather than just to topology. Candidate 3-manifolds based on hypothesised multiply imaged objects are being offered for observational refutation. The theoretical and observational sides of this rapidly developing subject have yet to make any serious contact, but the prospects of a significant detection in the coming decade may well propel the two together.

2 citations

Posted Content
TL;DR: In this article, a new idea of deriving a cosmological term from an underlying theory has been proposed in order to explain the expansion history of the universe and obtain the scale factor with this derived cosmology term and demonstrate that it reflects all the characteristics of the expanding universe in different era.
Abstract: A new idea of deriving a cosmological term from an underlying theory has been proposed in order to explain the expansion history of the universe. We obtain the scale factor with this derived cosmological term and demonstrate that it reflects all the characteristics of the expanding universe in different era so as to result in a transition from inflation to late acceleration through intermediate decelerating phases by this single entity. We further discuss certain observational aspects of this paradigm.

2 citations

Posted Content
TL;DR: Lesgourgues et al. as discussed by the authors analyzed the mathematical structure of the time co-ordinate of present day cosmological models, where these models include a cosmology constant term to account for the observed acceleration of the universe.
Abstract: Following the approach of Julien Lesgourgues [astro-ph/0409426], we analyze the mathematical structure of the time co-ordinate of present day cosmological models, where these models include a cosmological constant term to account for the observed acceleration of the universe: we find that in all cases, except for a set of measure zero in the parameter space, the time is given by an (abelian) integral on a torus; the imaginary period of this integral then gives a natural periodicity in imaginary time for the universe; following Stephen Hawking, this periodicity may be interpreted either as giving a fundamental mass scale for the universe, or (using Planck's constant) a fundamental temperature, or both. The precise structure that emerges suggests that the structure of time can be regarded as an order parameter arising perhaps in a phase transition in the early universe; one might hope that this structure would be predictable in any fundamental theory.

2 citations

Book ChapterDOI
01 Dec 2007

2 citations

Journal ArticleDOI
TL;DR: In this paper, the authors present a review of existing three-dimensional techniques for constraining and/or detecting the space-like hypersurface of the observable universe, using X-ray bright clusters of galaxies and quasars.
Abstract: The space-like hypersurface of the Universe at the present cosmological time is a three-dimensional manifold. A non-trivial global topology of this space-like hypersurface would imply that the apparently observable universe (the sphere of particle horizon radius) could contain several images of the single, physical Universe. Recent three-dimensional techniques for constraining and/or detecting this topology are reviewed. Initial applications of these techniques using X-ray bright clusters of galaxies and quasars imply (weak) candidates for a non-trivial topology.

2 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202320
202247
20216
202010
201910
201814