1. TESTING SCALING RELATION IN SITUATIONS OF EXTREME MERGERGALAXY 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. Rumors say X-ray mass underestimates the true mass GOALS Rasia et al 04, 07 Understand eventual bias!! Compare X-ray method with Lensing 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 under M eq idrodinamico over RTM, Rasia Tormen Moscardini,04

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)

6. over under

7. LENSINGThe 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) over under

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. COMPARING THE 2 ESTIMATES PROJECTING THE X-RAY

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

12. SCALING RELATIONS by Kravtsov et al 06 Mtot = 1014.41 (TX/3 keV)1.521 1014.35 (Mgas/2 1013)0.921 1014.27 (YX/4 1013)0.581 Yx=Mgas TX all clusters [7101321015]Msun/h all z (=0,0.6) All quantities at R500 excluding 0.15 R500

13. SIMULATIONS ONE SPECIAL CLUSTER • Physics: radiative cooling,uniform time-dependent UV background, star formation from multi-phase interstellar medium, galactic winds powered by SN Active dynamic history and strong merging (Mach number 2.5),merging mass ratio 1:10 Detachment between dark matter and gas component ONE STRONG MERGER 1 million particles inside R200, merging mass ratio 1:1

14. EVOLUTION INTRINSIC QUANTITIES

15. SCALING RELATION

16. GIANT COVARIANCE MATRIX

17. CONCLUSION Gravitational lensing is a good way to measure cluster masses. BUT substructures influences the WL and triaxiality can have drammatic effect on deprojected masses. 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-Mgas and M-YX are particularly strong and maintained a small scatter also in the case of extreme merger Other excellent choices can be DM or YSZ