1. TESTING SCALING RELATION IN SITUATIONS OF EXTREME MERGER GALAXY CLUSTERS MASS ELENA RASIA (University of Michigan) IN COLLABORATION WITH MAXIM MARKEVITCH (CFA), GUS EVRARD (UoM), BECKY STANECK (UoM), KLAUS DOLAG(MPA), PASQUALE MAZZOTTA (CFA, UNIVERSITY OF ROME), MASSIMO MENEGHETTI (OBSERVATORY OF BOLOGNA),

2. THESE GUYS ARE BIG!! WHY DO I CARE TO QUANTIFY THEIR MASS AND HOW CAN I MEASURE IT? Cluster mass is a fundamental quantity and is fundamental to do cosmology with clusters… There are some “direct” ways to obtain it from the sky: via X-ray, gravitational lensing, dynamical analysis in optical, combining different measurements (X-SZ). There are several indirect ways: scaling relation between an easy observable quantity and the total mass.

3. GOALS Understand eventual bias!! Compare X-ray method with Lensing Rumors say X-ray mass underestimates the true mass Rasia et al 04, 07 Scaling relation how they behave during merger? What can we do with 10,000/ 100,000 clusters?

4. X-ray mass in theory M eq idrostatico M eq idrodinamico RTM, Rasia Tormen Moscardini,04 over under

5. X-ray mass in observation XMM Chandra observations Surface brightness profile Temperature profile Two methods to estimate the mass via hydrostatic equilibrium equation –Forward (à la Vikhlinin et al. 05) –Backward (à la Ettori et al 2002)

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7. LENSING The projected mass STRONG LENSING: fit multiple images, arcs, etc., using “lenstool” (Kneib et al. 1993, Jullo et al. 2007) WEAK LENSING: measure shear with KSB; then (i) fit via NFW, (ii) aperture mass densitometry SL+WL:no-parametric mass reconstruction (Merten et al 2008) under over

8. Do we measure well the mass through lensing reconstruction? Generally: YES! We do measure correctly the mass… but we need to take care of substructures A single parametric model can be inaccurate

9. COMPARING THE 2 ESTIMATES DEPROJECTING LENSING Triaxiality problematics

10. PROJECTING THE X-RAY COMPARING THE 2 ESTIMATES

11. Difficulty to compare the 2 estimates The is a fundamental limit in which 3D masses can be measured via lensing for triaxiality

12. M tot = 10 14.41 (T X /3 keV) 1.521 10 14.35 (M gas /2 10 13 ) 0.921 10 14.27 (Y X /4 10 13 ) 0.581 Y x =M gas T X SCALING RELATIONS all clusters [710 13 210 15 ]M sun /h all z (=0,0.6) All quantities at R 500 excluding 0.15 R 500 by Kravtsov et al 06

13. Physics: radiative cooling,uniform time-dependent UV background, star formation from multi-phase interstellar medium, galactic winds powered by SN SIMULATIONS Active dynamic history and strong merging (Mach number 2.5),merging mass ratio 1:10 Detachment between dark matter and gas component 1 million particles inside R 200, merging mass ratio 1:1 ONE SPECIAL CLUSTER ONE STRONG MERGER

14. EVOLUTION INTRINSIC QUANTITIES

15. SCALING RELATION

16. GIANT COVARIANCE MATRIX

17. CONCLUSION We test the robustness of the scaling relation and we find that they are satisfied also in the case of a strong merger. The M-M gas and M-Y X are particularly strong and maintained a small scatter also in the case of extreme merger Gravitational lensing is a good way to measure cluster masses. BUT substructures influences the WL and triaxiality can have drammatic effect on deprojected masses. Other excellent choices can be  DM or Y SZ