TESTING SCALING RELATION IN SITUATIONS OF EXTREME MERGER GALAXY CLUSTERS MASS

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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),
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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.
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GOALS
Rumors say X-ray mass underestimates the true mass
Rasia et al 04, 07
Compare X-ray method with Lensing

• Understand eventual bias!!

Scaling relation how they behave during merger?
What can we do with 10,000/ 100,000 clusters?
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X-ray mass in theory
M eq idrostatico
under
M eq idrodinamico
over
RTM, Rasia Tormen Moscardini,04
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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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over
under
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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 SLWLno-parametric mass
reconstruction (Merten et al 2008)
over
under
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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
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COMPARING THE 2 ESTIMATES

• DEPROJECTING LENSING
• Triaxiality problematics

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COMPARING THE 2 ESTIMATES

• PROJECTING THE X-RAY

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

• Physics radiative cooling,uniform time-dependent
  UV background, star formation from multi-phase
  interstellar medium, galactic winds powered by SN

ONE SPECIAL CLUSTER
Active dynamic history and strong merging (Mach
number 2.5),merging mass ratio 110 Detachment
between dark matter and gas component
ONE STRONG MERGER
1 million particles inside R200, merging mass
ratio 11
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EVOLUTION INTRINSIC QUANTITIES
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SCALING RELATION
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GIANT COVARIANCE MATRIX
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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
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