Through the looking glass: why the `cosmic horizon' is not a horizon
Abstract
The present standard model of cosmology, Λ cold dark matter (ΛCDM), contains some intriguing coincidences. Not only are the dominant contributions to the energy density approximately of the same order at the present epoch, but we also note that contrary to the emergence of cosmic acceleration as a recent phenomenon, the time-averaged value of the deceleration parameter over the age of the Universe is nearly zero. Curious features like these in ΛCDM give rise to a number of alternate cosmologies being proposed to remove them, including models with an equation of state w = -1/3. In this paper, we examine the validity of some of these alternate models and we also address some persistent misconceptions about the Hubble sphere and the event horizon that lead to erroneous conclusions about cosmology.
Research undertaken as part of the Commonwealth Cosmology Initiative (CCI: http://www.thecci.org), an international collaboration supported by the Australian Research Council. E-mail: pimvanoirschot@gmail.com- Publication:
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Monthly Notices of the Royal Astronomical Society
- Pub Date:
- June 2010
- DOI:
- 10.1111/j.1365-2966.2010.16398.x
- arXiv:
- arXiv:1001.4795
- Bibcode:
- 2010MNRAS.404.1633V
- Keywords:
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- cosmology: theory;
- Astrophysics - Cosmology and Nongalactic Astrophysics
- E-Print:
- Accepted for publication by MNRAS, 6 pages, 3 figures