Enrichment of Clusters

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Enrichment of Clusters

• Andy Fabian
• Institute of Astronomy
• Cambridge UK
• With help from Jeremy Sanders

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Metals in the intracluster medium

• The intracluster medium in galaxy clusters is
  enriched on average to 1/3 solar

CCD spectrum from Chandra of Centaurus
cluster Sanders Fabian (2006a)? Z 1-1.5
solar
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Chandra X-ray spectrum of Perseus
cluster(residuals from Bremsstrahlung fit shown)
Sanders, Fabian, Allen Schmidt 2003
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Centaurus cluster with XMM RGS
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Cool core vs Non cool core
X-ray Surface Brightness shown on z-axis
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Temperature and radiative cooling time
profilesin regular relaxed COOL CORE clusters
Allen et al
Voigt et al
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Fabian94
Solid-CF, open-NCF
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Enhanced metals in the core
Non-cool core De Grandi Molendi (2001)?
Cool core
Cool core/cooling flow clusters show enhanced
metals in core (e.g. Fukazawa et al 1994, Allen
Fabian 1998)? They also show higher
emission-weighted average metallicities
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Baldi
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Lockman Hole z1.14 cluster kT5 keV
Hashimoto04
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Maugham et al
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Lets look at the details in nearby clusters

• Also see work by Baumgartner
• de Plaa
• Werner

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H Russell, Sanders Fabian (in prep)
A262
Direct Spectral Deprojection
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A2204 Sandersin prep
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900ks Chandra image of Perseus clusterFabian06
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Perseus metallicity map
Perseus metallicity map Regions contain gt4x104
counts Sanders Fabian (2007) see Sanders et
al (2004, 2005)
2' (45kpc)?
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Pushed high metallicity gas?
Metallicity map
330 MHz emission
74 MHz emission
High metallicity ridge
Evidence for ancient bubble?
Sanders, Fabian Dunn (2005)?
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Ha from WIYN Conselice01
NGC1275
VISCOUS?
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The Centaurus cluster
Inner core of the Centaurus cluster 200 ks
Chandra observation RGB image SandersFabian
02.05Fabian, Sanders05
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Centaurus temperature map
Crawford et al 2005
Temperature (keV)?
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Centaurus temperature and metals
Fabian et al (2005)?
50 kpc
3
1
0
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Temperature (keV)?
Metallicity (solar units)?
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Centaurus in different elements
Sanders Fabian (2006)?
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Cen cluster Abundance profileimplies little
diffusion/mixing Graham06 (following method of
Rebusco05)
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Supernova fractions
Sanders Fabian (2006)?

• Significant amount from Type II supernovae
  (30)?
• Therefore large amount of star formation in the
  Centaurus cluster
• Either massive initial burst
• Continuous 5 M?/yr
• Likely to have been undisturbed for 8 Gyr
• Close heating/cooling balance
• Allowed by Mg2 index

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Cool gas in the Centaurus cluster
Factor 10 temp range
T-sensitive lines indicate gas around 0.4
keV compared to gt4 keV in outer parts of cluster
Ne X/Fe
Fe XVII
Si
Mg XII
O VIII
N VIII
170 ks XMM-Newton RGS exposure Sanders 07
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Conclusions

• Metals in the intracluster medium are
  inhomogeneous on 5 kpc scales
• The central abundance drops are still
  unexplained.
• Any AGN feedback must preserve high Z blobs, and
  must preserve the steep abundance gradient
• Heating needs to be gentle and distributed
• However there is evidence bubbles can move some
  metals around

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Sanders04 Perseus
Baumgartner05 273 clusters
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Cooling in Centaurus?
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High metallicity blob
High metallicity blob dragged by bubble?
Ha
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The blob in detail

• No temperature correlation
• 2.6x104 solar masses of Fe in blob
• Requires 3.7x104 Type Ia SNae
• Diffusion timescale 40 Myr (using Rebusco et al
  2005)?
• Buoyancy timescale 100 Myr (Dunn et al 2006)?
• Diffusion timescale implies 0.1 Ia SN/century

Sanders Fabian (in prep.)?
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Hatch06
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Halpha WIYN
0.5 keV
109 M? consistent with 60 M?/yr
Multiphase cool gas in Perseus
Ha from Conselice et al 2001
1 keV
4 keV
2 keV
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Ha from WIYN Conselice et al 01
Perseus (see Fabian, Sanders, et al 2003b)?
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The Centaurus cluster
Inner core of the Centaurus cluster 200 ks
Chandra observation RGB image Fabian et al
(2005)?
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Temperature maps
5800 regions
10 000 counts per spectral region, binned using
Contour binning (Sanders 06)?
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Entropy and pressure
kT EM-1/3
kT EM1/2
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Metallicity of the ICM

• ICM is enriched at 0.3Solar in heavy elements
• ICM is not just primordial gas
• must contain gas processed through stars, and
  then removed from the constituent galaxies
• most likely mechanisms for injecting metals into
  the ICM are through
• supernova explosions / galactic winds
• ram pressure stripping of gas from galaxies by
  the ICM
• Constrains history and population of massive star
  formation within the galaxies

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• ...current observed mass loss from cluster
  galaxies would only produce 3 of the ICM in
  H0-1
• need a stage of early, rapid star formation in
  galaxies
• energetic S/N explosions that drive processed
  material from galaxies at early epochs of the
  cluster
• relative abundances of Si, S, Fe etc ? metals
  from Type II s/n
• 1011Mo of processed gas ejected from galaxies at
  Solar abundance
• becomes diluted on mixing with the primordial
  component of the ICM
• gas loss continues with ram pressure stripping by
  the ICM ( Type I s/n winds?)
• (s/n explosions also can act as a pre-heating
  mechanism for the gas)

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• Galaxy groups at T ? 1.5keV have Z ? 1/6 Solar
• ratio of elements (mainly Fe) ? Type Ia s/n
  important
• different SF history and processed matter lost
  through winds to IGM

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Lack of cool X-ray emitting gas
Spectra imply less than 10 of cooling rates
expected from luminosity profiles Typically
temperature goes down to 1/2 to 1/3 of outer
temperature
Fe XVII lines (indicating temperature 0.7
keV)? missing
2A 0335096 de Plaa
see also Peterson et al 01, 03, Kaastra et al 01,
03, Tamura et al 01,Boehringer..
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Temperature and radiative cooling time
profilesin regular relaxed clusters
Cooling?
Allen et al
Voigt et al