Cosmography and constraints on the equation of state of the Universe in various parametrizations
By Alejandro Aviles, C. Gruber, Orlando Luongo, Hernando Quevedo. 2012
191 citations recorded by the source corpus.
We use cosmography to present constraints on the kinematics of the Universe, without postulating any underlying theoretical model. To this end, we use a Monte Carlo Markov Chain analysis to perform comparisons to the supernova Ia Union 2 compilation, combined with the Hubble Space Telescope measurements of the Hubble constant, and the Hubble parameter datasets. We introduce a sixth order cosmographic parameter and show that it does not enlarge considerably the posterior distribution when comparing to the fifth order results. We also propose a way to construct viable parameter variables to be used as alternatives of the redshift $z$. These can overcome both the problems of divergence and lack of accuracy associated with the use of $z$. Moreover, we show that it is possible to improve the numerical fits by re-parameterizing the cosmological distances. In addition, we constrain the equation of state of the Universe as a whole by the use of cosmography. Thus, we derive expressions which can be directly used to fit the equation of state and the pressure derivatives up to fourth order. To this end, it is necessary to depart from a pure cosmographic analysis and to assume the Friedmann equations as valid. All our results are consistent with the $\Lambda$CDM model, although alternative fluid models, with nearly constant pressure and no cosmological constant, match the results accurately as well.
Subfields: Astronomy and Astrophysics
View Paper: https://www.semanticscholar.org/paper/221ff9b72003d83b3908f2ea9f97f7464faedca3
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In Astronomy and Astrophysics
- Bharat Ratra
- Omer Farooq
- Tiberiu Harko
- M. Setare
- Pierre-Henri Chavanis
- Hai-Bo Yu
- Fa-yin Wang
- S. Tsujikawa
Citations in the corpus
- HUBBLE PARAMETER MEASUREMENT CONSTRAINTS ON THE COSMOLOGICAL DECELERATION–ACCELERATION TRANSITION REDSHIFT (2013, methodology): “…models we consider here.4 Of interest to us here are measurements of the Hubble parameter as a function of redshift (e.g., Jimenez et al. 2003; Samushia & Ratra 2006; Samushia et al. 2007; Sen & Scherrer 2008; Chen & Ratra 2011b; Duan et al. 2011; Aviles et al. 2012; Seikel et al. 2012).”