Chandra observations of the central region of Abell 3112 . M. Takizawa (Yamagata Univ.) C. L. Sarazin, E. L. Blanton (Univ. of Virginia) G. B. Taylor (NRAO). Introduction . We have a lot of unsolved problems about the cluster center. Radiative cooling (cooling flows) Where is cold gas ?
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M. Takizawa (Yamagata Univ.)
C. L. Sarazin, E. L. Blanton(Univ. of Virginia)
G. B. Taylor (NRAO)
0.3 – 10.0 keV
The image has been background
subtracted and exposure
On large scales, the cluster
is quite symmetric and
to be no substrcture.
We fitted the image with a concentric
elliptical isophotal model to get a residual component.
Obs. Data =
elliptical isophotal model + residual
Excess emission (black) appears
to surround the radio lobes.
Probable interaction between
ICM and radio lobes
Interacting region is limited to very
central region (r～ 10”)
Gray scale: residual (X-ray)
Contours: 1.32 GHz (radio)
Solid crosses: when the absorption is allowed to vary.
Dashed crosses: when the absorption is fixed to the Galactic value.
Clear temperature decrease and abundance increase
towards the center.
The data were fitted with
MEKAL + MKCFLOW
Total mass deposition rate: 44.46+52.07-32.50 solar mass/yr
This value is much lower than that derived from ROSAT
and EXOSAT imaging analysis (～400 solar mass/yr).
Total Spectrum (r<157”):
The data are fitted with MEKAL + MKCFLOW , where the Tlow in MKCFLOW is allowed to vary.
The mass deposition rate is comparable with the former (ROSAT, EXOSAT) results.
However, the Tlow in MKCFLOW is not very low.
tcool=8.5×1010 yr (np/10-3cm-3)-1 (T/108K) ½
t cond=9.1×106 yr (ne/10-3cm-3)(lT/100kpc)2 (T/108K)-5/2 (lnΛ/40)
where、lT=T/(dT/dr)、Spitzer’s conductivity is used。
Circles: cooling time
Squares: conduction time
Inside cooling radius (tcool < 2.0×1010 yr), conduction time
is comparable or shorter than cooling time.
(c.f. rcool～ 250 kpc)