Projeto de parâmetros de limitações cosmológicas

CHANDRA CLUSTER COSMOLOGY PROJECT III: COSMOLOGICAL PARAMETER CONSTRAINTS

A. Vikhlinin et al 2009 ApJ 692 1060-1074 doi: 10.1088/0004-637X/692/2/1060

A. Vikhlinin1,2, A. V. Kravtsov3, R. A. Burenin2, H. Ebeling4, W. R. Forman1, A. Hornstrup5, C. Jones1, S. S. Murray1, D. Nagai6, H. Quintana7 and A. Voevodkin2,8

1 Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA

2 Space Research Institute (IKI), Profsoyuznaya 84/32, Moscow, Russia

3 Department of Astronomy and Astrophysics, Kavli Institute for Cosmological Physics, Enrico Fermi Institute, University of Chicago, Chicago, IL 60637, USA

4 Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96822, USA

5 National Space Institute, Technological University of Denmark, Juliane Maries Vej 30, DK-2100 Copenhagen, Denmark

6 Department of Physics and Yale Center for Astronomy & Astrophysics, Yale University, New Haven, CT 06520, USA

7 Departamento de Astronomia y Astrofisica, Pontificia Universidad Catolica de Chile, Casilla 306, Santiago, 22, Chile

8 Los Alamos National Laboratory, Los Alamos, NM 87545, USA

ABSTRACT:

Chandra observations of large samples of galaxy clusters detected in X-rays by ROSAT provide a new, robust determination of the cluster mass functions at low and high redshifts. Statistical and systematic errors are now sufficiently small, and the redshift leverage sufficiently large for the mass function evolution to be used as a useful growth of a structure-based dark energy probe. In this paper, we present cosmological parameter constraints obtained from Chandra observations of 37 clusters with z = 0.55 derived from 400 deg2 ROSAT serendipitous survey and 49 brightest z 0.05 clusters detected in the All-Sky Survey. Evolution of the mass function between these redshifts requires ΩΛ > 0 with a ~5σ significance, and constrains the dark energy equation-of-state parameter to w 0 = –1.14 ± 0.21, assuming a constant w and a flat universe. Cluster information also significantly improves constraints when combined with other methods. Fitting our cluster data jointly with the latest supernovae, Wilkinson Microwave Anisotropy Probe, and baryonic acoustic oscillation measurements, we obtain w 0 = –0.991 ± 0.045 (stat) ±0.039 (sys), a factor of 1.5 reduction in statistical uncertainties, and nearly a factor of 2 improvement in systematics compared with constraints that can be obtained without clusters. The joint analysis of these four data sets puts a conservative upper limit on the masses of light neutrinos ∑m ν < 0.33 eV at 95% CL. We also present updated measurements of ΩM h and σ8 from the low-redshift cluster mass function.

Key words:

cosmological parameters; cosmology: observations; galaxies: clusters: general; dark matter; surveys

Print publication: Issue 2 (2009 February 20)

Received 2008 May 12, accepted for publication 2008 October 22

Published 2009 February 23