Constraining the dark energy with galaxy clusters X-ray data

Lima, J. A. S.; Cunha, J. V.; Alcaniz, J. S.

Constraining the dark energy with galaxy clusters X-ray data

Authors

Lima, J. A. S.

Cunha, J. V.

Alcaniz, J. S.

Description

The equation of state characterizing the dark energy component is constrained by combining Chandra observations of the X-ray luminosity of galaxy clusters with independent measurements of the baryonic matter density and the latest measurements of the Hubble parameter as given by the HST key project. By assuming a spatially flat scenario driven by a "quintessence" component with an equation of state $p_x = ωρ_x$ we place the following limits on the cosmological parameters $ω$ and $Ω_{\rm{m}}$: (i) $-1 \leq ω\leq -0.55$ and $Ω_{\rm m} = 0.32^{+0.027}_{-0.014}$ (1$σ$) if the equation of state of the dark energy is restricted to the interval $-1 \leq ω< 0$ (\emph{usual} quintessence) and (ii) $ω= -1.29^{+0.686}_{-0.792}$ and $Ω_{\rm{m}} = 0.31^{+0.037}_{-0.034}$ ($1σ$) if $ω$ violates the null energy condition and assume values $< -1$ (\emph{extended} quintessence or ``phantom'' energy). These results are in good agreement with independent studies based on supernovae observations, large-scale structure and the anisotropies of the cosmic background radiation.
6 pages, 4 figures, LaTeX