On the evolution of Cool Core Clusters Joana Santos (INAF-Trieste) Piero Rosati (ESO), Paolo Tozzi...
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Transcript of On the evolution of Cool Core Clusters Joana Santos (INAF-Trieste) Piero Rosati (ESO), Paolo Tozzi...
On the evolution of Cool Core Clusters
Joana Santos (INAF-Trieste)
Piero Rosati (ESO), Paolo Tozzi (INAF-Trieste), Hans Boehringer (MPE), Stefano Ettori (INAF-
Bologna)
IBERICOS09, Madrid, April 2009
16 April 2009 Joana Santos (INAF-Trieste) IBERICOS09 2
Introduction Clusters of galaxies: • Largest gravitationally bound systems in the Universe, dominated by DM, formed at z>2• Baryon content: hot gas (intracluster medium) + galaxies Cosmological probes Ideal astro labs to study complex physics of baryons
Cool Core Clusters (CCC)Highly relaxed galaxy clusters show central
radiative cooling
• Core temperature: Tcore ~ 1/3 Tavg
• Central Surface Brightness (SB) excess
• Cooling time, tcool shorter than Hubble Time
16 April 2009 Joana Santos (INAF-Trieste) IBERICOS09 3
Motivation
Why are CCC important?• Cooling Flow problem: cool cores are not too cold! likely heating mechanisms: AGN feedback + mergers
• CCC affect scaling relations – connection to cluster mass• Cosmology using galaxy clusters: cluster detection
Current knowledge on CC abundance• Local Universe: 50 - 70% Peres et al. 98, Mittal et al. 08 • Since z=0.4: No evolution Bauer et al. 05• 0.5 < z < 0.9 -> Lack of cool cores?... Vikhlinin et al. 06
• Beyond z=1 ?... Study population of CCC @ 0.7 < z < 1.4
using high resolution CHANDRA images J.S.Santos et al. A&A 2008
16 April 2009 Joana Santos (INAF-Trieste) IBERICOS09 4
Data
CHANDRA archive
Low-z sample: 11 clusters, 0.15 < z < 0.3• selection: >10000 cts, T > 5 keV• heterogeneous sample Strong CC
(control sample) Moderate CC
Non CC
High-z sample: 15 clusters, 0.7 < z < 1.4 representative sample Rosati et al. 98
16 April 2009 Joana Santos (INAF-Trieste) IBERICOS09
Low redshift cluster sample
8”
16 April 2009 Joana Santos (INAF-Trieste) IBERICOS09
High
redshift
cluster
sample
3”
16 April 2009 Joana Santos (INAF-Trieste) IBERICOS09 7
Surface Brightness fitting at high-z: single & double β models
0.53b2/1+
rcr+So=S
β model:
S
(ct
s/s/
pix)
Cavaliere & Fusco-Femiano 76
1 β model: non-CC
2 β model: CC
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kpc)SB(r
kpc)SB(r=CSB
400
40
N
Surface Brightness Concentration, CSB
NCC CC
16 April 2009 Joana Santos (INAF-Trieste) IBERICOS09 9
Simulating clusters by cloning
Assumption: no intrinsic cluster evolution
Low redshift X-ray images (parameter free)
• Flux rescale: Luminosity distance, DL + K-correction (z,T)
• Spatial rescale (angular distance, DA)
Chandra PSF ~ 1”
-> Res = 8 kpc @ z=1
-> no PSF deconvolution
Cloning @ work:
16 April 2009 Joana Santos (INAF-Trieste) IBERICOS09 10
kpc)SB(r
kpc)SB(r=CSB
400
40
N
Surface Brightness Concentration, CSB
Clones recover same CSB of parent sample -> no z-dependence
NCC CC
16 April 2009 Joana Santos (INAF-Trieste) IBERICOS09 11
Scaled SB profiles
3 bins of CSB:
CSB > 0.155
0.075< CSB < 0.155
CSB < 0.075
Self Similar Scaling Law: 45.0 )1( zTSX
LOW-z Strong CC
Mod CC - - -
NCC
HIGH-z Mod CC - - -
NCC
Arnaud et al 2005
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Central Cooling Time, tcool
)(
5.22 Tn
Tnt
e
gcool
10 high-z cl
tcool < 10
Peterson & Fabian 2006
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Correlation tcool - CSB
93.0 SBcool Ct
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Conclusions
• Surface Brightness analysis: CSB + stacked SB profiles indicate a significant fraction of moderate CC @ 0.7< z<1.4
Absence of pronounced CC at high-z
• Cooling time supports SB results: 10/15 clusters tcool < Hubble time
(makes sense: distant galaxy clusters are dynamically younger …)
-> hint for evolution?
Future work: (X-ray) independent measurementIs there cold gas? How much? -> Search for optical emission (Hα)
ESO/SINFONI NIR spectroscopy of XMMUJ2235 @ z=1.4
(PI J.Santos)
16 April 2009 Joana Santos (INAF-Trieste) IBERICOS09 15
WFXT – Wide Field X-ray Telescope
PI: Riccardo Giacconi – ASTRO2010 DECADAL SURVEY
16 April 2009 Joana Santos (INAF-Trieste) IBERICOS09
High Redshift sample
RXJ1113V1221 RXJ2302 MS1137
RXJ1317 RXJ1350 RXJ1716 MS1054
RXJ1226 CLJ1415 RXJ0910 RXJ1252
RXJ0849 RXJ0848 XMMU J2235
`
CSB > 0.095
0.075 < CSB < 0.095
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