Study of Two Temperature and NonEquilibrium Ionization States ofPlasma in Merging Galaxy Clusters
Takuya Akahoriwith Kohji Yoshikawa, FIRST project team
10/30-11/1@Center for Computational Sciences,
University of Tsukuba

1/8Outline• Topic– Non-EQ states of ICM
in merging G.C.

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Ç™Ç±ÇÃÉsÉNÉ`ÉÉÇ¾å©ÇÈÇžÇ½Ç…ÇÕïKóvÇ-Ç ÅB• Contents– Introduction– Model and Method– Results– SummaryFig: the Mean temperature, electrontemperature, and OVI ionization
fraction of the intracluster gas inthe merging galaxy cluster

Super Computing 2007
Produced by K. Yoshikawa, T. Akahori,and FIRST project team

2/8Formation History• Standard ΛCDM model– Primordial perturbation– Jean’s instability– Galaxy clusters are formedin the dense region– Through mergers of smaller
objects such as galaxies,
galaxy groups and clusters

3K CMB (WMAP obs.)

Navarro et al. 1995

Evrard 1990

3/8Observations• Mpc scale density substructures– 1E0657-56 (Bullet)• Markevitch et al. 2002

X-ray intensity map X-ray intensity map(Abell2142)(1E0657-56)– Abell2142• Markevitch et al. 2000

• Mpc scale temperature
substructures– Perseus• Furusho et al. 2001

– Coma• Watanabe et al. 1999

X-ray temperaturemap (Perseus)

X-ray temperaturemap (Coma)4/8

Effects of Mergers• What kind of effects are seen in mergers?
– Compression/Heating ⇔Expansion/Cooling• Deviation from the equilibrium state– non-eq. e-i temperature state, non-eq. ionization state
Telectron / T
Ionization Fraction

Mean T

2T hydro-simulation (Takizawa 1999)

n~10-4cm-3,T~4*105K

Non-eq. ionization simulation(Yoshikawa, Sasaki 2006)

5/8Objective• In merging clusters, electron-ion temperature nonequilibrium, and ion ionization non-equilibrium havebeen suggested.
• Up to now, there are no 3D hydrodynamical simulation
which considers both the non-eq. states.

Objective•To see both the non-equilibrium states•When/Where do the non-EQ states appear?

•To predict the plasma state in observed merging clusters•Do 2T state and non-EQ ionization state really exist in the clusters?

6/8Method• N-body + SPH simulations• High performance PC Cluster
is the key to success.
– Non-EQ states– Virialization shock• We have an excellent solution,– FIRST Simulator!

Main Cluster

Simulation Outline

DM

Sub Cluster

Gas

Shock
Gravitye Recombination

He+eH+ Si14+
O6+• 36.1 TFlops• 1.6 TB memory• 22 TB storage
FIRST project logo, 256 nodes PC cluster

eIonization

X-ray

Brems.
UV

Fe24+
e e

Heavy Element

kT(keV)Xe
f/feq

7/8.005 .01 .05 .1 .5 1 3
5 8.95 .85 .75 .65 .55 .45 .35 .25 .15.55 .65 .75 .85 .95 1.05 1.15 1.25 1.35Results• A shock wave (M〜2) passed
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Ç™Ç±ÇÃÉsÉNÉ`ÉÉÇ¾å©ÇÈÇžÇ½Ç…ÇÕïKóvÇ-Ç ÅB– Non-EQ temperature and ionization
states are appreciable, and remains
for several Gyr.

Xe @ 9Gyr
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kT, OVII, SiXIII, FeXXV@9Gyr
OVII 2TOVII 1T

1Mpc
kT, SiXI@12Gyr8/8

Summary• Numerical simulation of two temperature and non-equilibrium
ionization states in merging galaxy clusters were carried out.
– The non-EQ states caused by mergers remained for several Gyr.
– We provided a good constraint for metal abundance.

Application (preliminary!) Abell399/Abell401 -Fujita et al. (2007)
kT, FeXXV(He-like Kα 6.7keV)