1. Observing galaxy cluster simulations with an X-ray telescope Elena Rasia Department of Physics, University of Michigan Chandra Fellows Symposium Harvard-Smithsonian Center for Astrophysics October 13, 2006

2. COSMOLOGY H 0 =71 +/- 2 km/s/Mpc  8 =0.9 +/- 0.03 n = 0.98 +/- 0.02   =0.72 +/-0.02  B =0.024 +/-0.003  DM h 2 =0.115+/-0.013 (Seljak et al. 2005) From: WMAP(1st year) SDSS 2dF weak lensing SNe Ia Ly-  forest Age of G.C. (Haiman et al 2005) Plank SNAP clusters H 0 =73 +/- 3 km/s/Mpc  8 =0.74 +/- 0.05 n = 0.951 +0.01/-0.02  B h 2 =0.0223 +/-0.0008  DM h 2 =0.127 +0.007/- 0.013  =0.09 +/- 0.03 From: WMAP (3rd year) (Spergel et al. 2006) DUNE (Dark Universe Explorer) DES (Dark Energy Survey) XEUS (X-ray Evolving Universe Spectroscopy mission) Constellation-X

3. X-MAS X-ray Map Simulator (Gardini et al 2004, Rasia et al. 2006) SIMULATIONS: GADGET/GADGET2 Tree + SPH (Springel et al.’01; Springel ‘05)  CMD (  M  0.27,    0.7,  8 =0.8/0.9, h=0.70) Explicit entropy conservation (Springel & Hernquist ‘02) Radiative cooling + uniform evolving UV background Multiphase model for star- formation + galactic winds (Springel & Hernquist ‘03) Thermal conduction (Jubelgas et al. ‘04; Dolag et al. ‘04) Chemical enrichment from Sn- Ia and II (Tornatore et al. ’04, ‘06) Reduced-viscosity SPH scheme (Dolag et al. ‘05) First part: Selection of los + projection into the sky, is quite general+ computation of the spectral emissivity Second part: Depend on the characteristics of the X-ray telescope and detector (Chandra ACIS-S, Chandra ACIS-I, XMM-Newton EPIC- MOS1&2 XMM- Newton EPIC-PN) X-RAY EVENT FILES which can be analyzed using the X-ray tools

4. X-ray Map Simulator

5. Main Results Contrast between temperature definitions in simulations and observations: T EW is not a good description of the X- ray spectroscopic temperature (Gardini et al. 2004) Temperature to use in simulations T SL ->cosmological consequence for M-T (Mazzotta et al 2004, Rasia et al. 2005) Study of systematics bias of mass measurement (Rasia et al. 2006) and metallicity measurement (Rasia et al. in prep.)

6. TEMPERATURES simulation X-ray observation The different degree of thermal homogeneity has strong implications on the temperature profiles: for the perturbed systems the spectral and emission- weighted temperature profiles are not in good agreement (Gardini et al. 2004)

7. beside being biased toward densest regions the spectroscopic temperature is also biased toward the coolest regions (Mazzotta et al. 2004)TEMPERATURES Emission-Weighted Spectroscopic-Like Shock frontNo Shock front Mazzotta et al. 2004, see also Vikhlinin 2006

8. COSMOLOGICAL IMPLICATIONS T SL =(0.70±0.01)T EW +(0.29±0.05) Rasia et al.2005, Kawahara et al. in prep Simple theoretical arguments supported by hydro N-body simulations suggest the existence for virialized gravitational systems of a tight relation between M-T: M 500 =M 0 (kT 500 /1keV) 

9. MASS-TEMPERATURE RELATION M sim M,M, M 0 is higher using T sl instead of T ew T_EW (Borgani et al.2004)T_SL (Rasia et al. 2005)

10. MASS-TEMPERATURE RELATION M sim M,M, Scatter reduced from 30 % to 16%

11. MASS BIAS Hydrostatic equilibrium equation Hydro(dynamic?) equilibrium equation (Rasia et al. 2004, see also Kay et al. 2004, Faltenbacher et al. 2005, Lau et al. 2006, Nagai et al. 2006) Gap explained by the velocity motions of the gas the is not completely at rest even in the center of the cluster

12. MASS BIAS The mass recovered through the HE equation are underestimated by 20%, half or more of which solved by including the kinetic pressure term (Rasia et al. 2006, see also Nagai et al. 2006). The mass measurements reconstructed via the  -model show a systematic underestimate, with typical deviation of about 40% at R 2500 and R 500.

13. SUMMARY Clusters are good probe to extract cosmological parameters To study systematics bias, to verify models and hypothesis and to test (X-ray, but not only…) methods we need SIMULATIONS We built X-MAS that allow us to make proper comparison between simulations and observations T EW is not a good description of T spec -> we propose another formulation T SL -> this has relevant cosmological consequence for M-T X-ray mass estimates present systematic bias due to different reasons -> this has to be taken into account in comparing different M-T relation present in literature