TESTING SCALING RELATION IN SITUATIONS OF EXTREME MERGER GALAXY CLUSTERS MASS
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Transcript of TESTING SCALING RELATION IN SITUATIONS OF EXTREME MERGER GALAXY CLUSTERS MASS
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