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),

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.

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 dowith 10,000/

100,000 clusters?

X-ray mass in theory

M eq idrostatico

M eq idrodinamico

RTM, Rasia Tormen Moscardini,04

€

M E (< x) = −xRvkbT(x)

Gμmp

d lnρ(x)

d ln x+d lnT(x)

d ln x

⎡ ⎣ ⎢

⎤ ⎦ ⎥

€

−xRvσ r

2(x)

G

d lnρ(x)

d ln x+d lnσ r

2(x)

d ln x+ 2β (x)

⎡

⎣ ⎢

⎤

⎦ ⎥

over

under

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)

under

over

LENSINGThe projected massSTRONG 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

Do we measure well the mass through lensing reconstruction?Generally: YES! We do measure correctly the mass… but we

need to take care of substructuresA single parametric model can be inaccurate

COMPARING THE 2 ESTIMATES

DEPROJECTING LENSING

Triaxiality problematics

PROJECTING THE X-RAY

COMPARING THE 2 ESTIMATES

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

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

SCALING RELATIONSSCALING RELATIONS

all clusters [7101321015]Msun/h all z (=0,0.6)

All quantities at R500 excluding 0.15 R500

by Kravtsov et al 06by Kravtsov et al 06

• 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 R200, merging mass ratio 1:1

ONE SPECIAL CLUSTER

ONE STRONG MERGER

EVOLUTION INTRINSIC QUANTITIES

SCALING RELATION

GIANT COVARIANCE MATRIX

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-Mgas and M-YX 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 YSZ