Improvements in the X-ray luminosity function and constraints on the cosmological parameters from X-ray luminous clusters
Abstract
Aims: We improve the current constraints on Ω_m, the dark-energy equation-of-state parameter, w, and σ_8, obtained from measurements of the X-ray luminosity function of galaxy clusters, namely MACS, the local BCS, and the REFLEX galaxy cluster samples with luminosities L > 3 × 1044 erg/s in the 0.1-2.4 keV band.
Methods: To this aim, we use Tinker and collaborators mass function instead of Jenkins and collaborators and the mass-luminosity relationship obtained by Del Popolo and collaborators.
Results: Using the same methods and priors as Mantz and collaborators, we find Ω_m = 0.28+0.05-0.04 and σ_8 = 0.78+0.04-0.05, for a ΛCDM universe, while the result of Mantz and collaborators gives less tight constraints Ω_m = 0.28+0.11-0.07 and σ_8 = 0.78+0.11-0.13. In the case of a wCDM model, we find Ω_m = 0.27+0.07-0.06, σ_8 = 0.81+0.05-0.06 and w = -1.3+0.3-0.4, while in Mantz and collaborators they are again less tight Ω_m = 0.24+0.15-0.07, σ_8 = 0.85+0.13-0.20 and w = -1.4+0.4-0.7. Combining the XLF analysis with the fgas+CMB+SNIa data set results in the constraint Ω_m = 0.269 ± 0.012, σ_8 = 0.81 ± 0.021 and w = -1.02 ± 0.04, to be compared with Mantz and collaborators, Ω_m = 0.269 ± 0.016, σ_8 = 0.82 ± 0.03 and w = -1.02 ± 0.06. The tightness of the last constraints obtained by Mantz and collaborators, are fundamentally due to the tightness of the fgas+CMB+SNIa constraints and not to their XLF analysis. Our findings, consistent with w = -1, lend additional support to the cosmological-constant model.
- Publication:
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Astronomy and Astrophysics
- Pub Date:
- May 2010
- DOI:
- 10.1051/0004-6361/200913133
- arXiv:
- arXiv:1001.1443
- Bibcode:
- 2010A&A...514A..80D
- Keywords:
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- cosmology: theory;
- cosmological parameters;
- Astrophysics - Cosmology and Extragalactic Astrophysics
- E-Print:
- 9 pages, 4 Figures. A&