1. Constraining the cosmological parameters with X-ray galaxy clusters S.Ettori (INAF Bologna) P.Tozzi (INAF Trieste), F.Terenziani (Univ. Bologna), L.Lovisari (Univ. Bologna), S.Borgani (Univ. Trieste), P.Rosati (ESO) et al.

2. Number density Abundance of galaxy clusters is sensitive to the normalization (  8 ) and shape (  m h) of the present-day power spectrum Voevodkin & Vikhlinin 04 71

3. Number density Abundance of galaxy clusters is sensitive to the normalization (  8 ) and shape (  m h) of the present-day power spectrum Reiprich 06

4. Gas mass fraction We combine a dynamical and a geometrical method: 1. baryonic content of galaxy clusters is representative of the cosmic baryon fraction Ω b / Ω m (White et al. 93, …) 2. f gas is assumed constant in cosmic time in very massive systems (Sasaki 96, Pen 97, Ettori & Fabian 99, …) To constrain the cosmological model Ω m +Ω  +Ω k =1

5. Gas mass fraction: the method  2 =  i (f bar, i / Y  Ω b / Ω m ) 2 /  i 2 f bar, i = f gas, i + f star, i f gas (<r 500 ) = M gas / M tot  d ang (  m,  , w) 3/2 f star = 1.64  0.10 e-2 (M tot / 3e14) -0.26  0.09 (Lin et al. 2003) = 0.1-0.2 f gas Ω b h 2 = 0.0189 ±0.0010 (PN, Burles et al. 01), Ω b h 2 = 0.0223 ±0.0008 (CMB, Spergel et al. 06), H 0 = 72 ± 8 km/s/Mpc (Freedman et al. 2001).

6. Gas mass fraction: Y(z) Ettori et al. 06 Y 500 = 0.903 (±0.004) +0.048 (±0.010) z R 500

7. Chandra data for 56 clusters @ 0.14<z<1.24 (Rosati et al. 02, Ettori et al. 03 & 04, Tozzi et al. 03, Balestra et al. 06)

8. An example: RXJ1252, z=1.235

10. A front is there: cold or hot?

11. An example: RXJ1252, z=1.237

13. R 500 = 0.592 (0.547, 0.741) Mpc (H 0 =70,  m =1-   =0.3) f gas = 0.097 (0.062, 0.120)

14. The sample: 56 hot clusters

15. Constraints on Ω m - Ω  Ω m = 0.23 (0.20, 0.29) Ω  =0.79 (<1.25) at 2  (95.4% 1 param)

16. Constraints on Ω m - Ω 

17. Constraints on Ω m - w Ω m = 0.22 (0.14, 0.27) w = -1.36 (-3.18, -0.45) at 2  (95.4% 1 param)

18. Complementary constraints on DE Three data sets: SN, CMB (WMAP1st+CBI+ACBAR) and Clusters Marginalized constraints (68.3%) w 0 = -1.05 ±0.11  m = 0.29 ±0.03 Rapetti, Allen & Weller (2005)