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


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


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”


High

redshift

cluster

sample

3”


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


kpc)SB(r

kpc)SB(r=CSB

400

40

N

Surface Brightness Concentration, CSB

NCC CC


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:


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


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


Central Cooling Time, tcool

)(

5.22 Tn

Tnt

e

gcool

10 high-z cl

tcool < 10

Peterson & Fabian 2006


Correlation tcool - CSB

93.0 SBcool Ct


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)


WFXT – Wide Field X-ray Telescope

PI: Riccardo Giacconi – ASTRO2010 DECADAL SURVEY


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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on the evolution of cool core clusters joana santos (inaf-trieste) piero rosati (eso), paolo tozzi...

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