Comparison of standard ruler and standard candle constraints on dark energy models
- Fisika Teorikoa, Zientzia eta Teknologiaren Fakultatea, Euskal Herriko Unibertsitatea, 644 Posta Kutxatila, 48080 Bilbao (Spain)
- Department of Physics, University of Ioannina (Greece)
We compare the dark energy model constraints obtained by using recent standard ruler data (baryon acoustic oscillations (BAO) at z = 0.2 and 0.35 and cosmic microwave background (CMB) shift parameters R and l{sub a}) with the corresponding constraints obtained by using recent type Ia supernovae (SnIa) standard candle data (ESSENCE+SNLS+HST from astro-ph/0701510). We find that, even though both classes of data are consistent with {Lambda}CDM (CDM: cold dark matter) at the 2{sigma} level, there is a systematic difference between the two classes of data. In particular, we find that for practically all values of the parameters ({Omega}{sub 0m},{Omega}{sub b}) in the 2{sigma} range of the three-year WMAP data (WMAP3) best fit, {Lambda}CDM is significantly more consistent with the SnIa data than with the CMB+BAO data. For example for ({Omega}{sub 0m},{Omega}{sub b}) = (0.24,0.042) corresponding to the best fit values of WMAP3, the dark energy equation of state parameterization w(z) = w{sub 0}+w{sub 1}(z/1+z) best fit is at a 0.5{sigma} distance from {Lambda}CDM (w{sub 0} = -1,w{sub 1} = 0) using the SnIa data and 1.7{sigma} away from {Lambda}CDM using the CMB+BAO data. There is a similar trend in the earlier data (SNLS versus CMB+BAO at z = 0.35). This trend is such that the standard ruler CMB+BAO data show a mild preference for crossing of the phantom divide line w = -1, while the recent SnIa data favor {Lambda}CDM. Despite this mild difference in trends, we find no statistically significant evidence for violation of the cosmic distance duality relation {eta} {identical_to} d{sub L}(z)/d{sub A}(z)(1+z){sup 2}=1. For example, using a prior of {Omega}{sub 0m} = 0.24, we find {eta} = 0.95 {+-} 0.025 in the redshift range 0<2, which is consistent with distance duality at the 2{sigma} level.
- OSTI ID:
- 22156682
- Journal Information:
- Journal of Cosmology and Astroparticle Physics, Vol. 2008, Issue 07; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 1475-7516
- Country of Publication:
- United States
- Language:
- English
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