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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.
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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
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Number density Abundance of galaxy clusters is sensitive to the normalization ( 8 ) and shape ( m h) of the present-day power spectrum Reiprich 06
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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
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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).
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Gas mass fraction: Y(z) Ettori et al. 06 Y 500 = 0.903 (±0.004) +0.048 (±0.010) z R 500
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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)
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An example: RXJ1252, z=1.235
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A front is there: cold or hot?
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An example: RXJ1252, z=1.237
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R 500 = 0.592 (0.547, 0.741) Mpc (H 0 =70, m =1- =0.3) f gas = 0.097 (0.062, 0.120)
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The sample: 56 hot clusters
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Constraints on Ω m - Ω Ω m = 0.23 (0.20, 0.29) Ω =0.79 (<1.25) at 2 (95.4% 1 param)
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Constraints on Ω m - Ω
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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)
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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)
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