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Title: Is cosmic acceleration slowing down?

We investigate the course of cosmic expansion in its recent past using the Constitution SN Ia sample, along with baryon acoustic oscillations (BAO) and cosmic microwave background (CMB) data. Allowing the equation of state of dark energy (DE) to vary, we find that a coasting model of the universe (q{sub 0}=0) fits the data about as well as Lambda cold dark matter. This effect, which is most clearly seen using the recently introduced Om diagnostic, corresponds to an increase of Om and q at redshifts z < or approx. 0.3. This suggests that cosmic acceleration may have already peaked and that we are currently witnessing its slowing down. The case for evolving DE strengthens if a subsample of the Constitution set consisting of SNLS+ESSENCE+CfA SN Ia data is analyzed in combination with BAO+CMB data. The effect we observe could correspond to DE decaying into dark matter (or something else)
Authors:
 [1] ;  [2] ;  [3] ;  [4]
  1. Department of Physics, University of Oxford, 1 Keble Road, Oxford, OX1 3NP (United Kingdom)
  2. Inter University Centre for Astronomy and Astrophysics, Post Bag 4, Ganeshkhind, Pune, 411007 (India)
  3. Landau Institute for Theoretical Physics, Moscow 119334 (Russian Federation)
  4. (Japan)
Publication Date:
OSTI Identifier:
21308583
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review. D, Particles Fields; Journal Volume: 80; Journal Issue: 10; Other Information: DOI: 10.1103/PhysRevD.80.101301; (c) 2009 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ACCELERATION; BARYONS; EQUATIONS OF STATE; EXPANSION; NONLUMINOUS MATTER; OSCILLATIONS; RED SHIFT; RELICT RADIATION; SLOWING-DOWN; UNIVERSE