Comment on "Constraining the smoothness parameter and dark energy using observational H(z) data"

Abstract

In this Comment we discuss a recent analysis by Yu et al. [RAA 11, 125 (2011)] about constraints on the smoothness $\alpha$ parameter and dark energy models using observational $H(z)$ data. It is argued here that their procedure is conceptually inconsistent with the basic assumptions underlying the adopted Dyer-Roeder approach. In order to properly quantify the influence of the $H(z)$ data on the smoothness $\alpha$ parameter, a ${\chi }^2$-test involving a sample of SNe Ia and $H(z)$ data in the context of a flat $\Lambda$CDM model is reanalyzed. This result is confronted with an earlier approach discussed by Santos et al. (2008) without $H(z)$ data. In the (${\Omega }_m,\alpha$) plane, it is found that such parameters are now restricted on the intervals $0.66\le \alpha \le 1.0$ and $0.27\le {\Omega }_m\le 0.37$ within 95.4% confidence level (2$\sigma$), and, therefore, fully compatible with the homogeneous case. The basic conclusion is that a joint analysis involving $H(z)$ data can indirectly improve our knowledge about the influence of the inhomogeneities. However, this happens only because the $H(z)$ data provide tighter constraints on the matter density parameter ${\Omega }_m$.

3 pages, 1 figure, submitted to Research in Astronomy and Astrophysics

References in corpus (7)

• New Hubble Space Telescope Discoveries of Type Ia Supernovae at z > 1: Narrowing Constraints on the Early Behavior of Dark Energy
• Constraints on the redshift dependence of the dark energy potential
• Improved Constraints on the Acceleration History of the Universe and the Properties of the Dark Energy
• Dark energy as a mirage
• Clustering, Angular Size and Dark Energy
• Constraining the dark energy and smoothness-parameter with supernovae
• Constraints on smoothness parameter and dark energy using observational $H(z)$ data

Cited by in corpus (7)

• Constraining the dark energy and smoothness parameter with type Ia Supernovae and Gamma-Ray Bursts
• Supernovae as probes of cosmic parameters: estimating the bias from under-dense lines of sight
• Observational constraints from SNe Ia and Gamma-Ray Bursts on a clumpy universe
• Unbiased constraints on the clumpiness of universe from standard candles
• Influence of Small-Scale Inhomogeneities on the Cosmological Consistency Tests
• Studying light propagation in a locally homogeneous universe through an extended Dyer-Roeder approach
• The $m$-$z$ relation for Type Ia supernovae: safety in numbers or safely without worry?