Improvements in the X-ray luminosity function and constraints on the cosmological parameters from X-ray luminous clusters
Dipartimento di Fisica e Astronomia, Università di Catania, Viale Andrea Doria 6, 95125 Catania, Italy e-mail: firstname.lastname@example.org
2 Argelander-Institut für Astronomie, Auf dem Hügel 71, 53121 Bonn, Germany
3 Dipartimento di Metodologie Chimiche e Fisiche per l'Ingegneria, Univesità di Catania, Viale A. Doria 6, 95125, Catania, Italy
4 Osservatorio Astrofisico di Catania, Istituto Nazionale di Astrofisica, via S. Sofia 78, 95123, Catania, Italy
Accepted: 31 December 2010
Aims. We improve the current constraints on Ωm, the dark-energy equation-of-state parameter, w, and σ8, 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 Ωm = and σ8 = , for a ΛCDM universe, while the result of Mantz and collaborators gives less tight constraints Ωm = and σ8 = . In the case of a wCDM model, we find Ωm = , σ8 = and w = , while in Mantz and collaborators they are again less tight Ωm = , σ8 = and w = . Combining the XLF analysis with the fgas+CMB+SNIa data set results in the constraint Ωm = 0.269 ± 0.012, σ8 = 0.81 ± 0.021 and w = -1.02 ± 0.04, to be compared with Mantz and collaborators, Ωm = 0.269 ± 0.016, σ8 = 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.
Key words: cosmology: theory / cosmological parameters
© ESO, 2010