Molecular gas in cooling flows Interplay with AGN and starbursts

Ph. Salomé & F. Combes

APEX workshop

3- February 2006

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Cooling flows in galaxy clusters

Cooling time < Hubble time at the center of clusters Gas Flow, 100 to 1000 Mo/yr

Problem: cold gas or stars formed are not detected?

Today, the amplitude of the flow has been reduced by 10 and the cold gas is detectedEdge (2001) Salomé & Combes (2003) 23 detected galaxies in CO

Results from Chandra & XMM: cooling flow self-regulated

Re-heating process, feedback due to the active nucleus or blackHole: schocks, jets, acoustic waves, bubbles...

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Sound wavesin Perseus

with Chandra

Fabian et al 2003NGC 1275=Abell 426

Mechanical energy muchlarger than Lbol(Binney & Tabor 1995,Churazov et al 2002)

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Detection of CO with

IRAM-30m

CO surveySelected on dM/dtand H

6-10 detectionsamong 32 galaxies

Masses between3 108 - 4 1010Mo

Mgas versus z, Stars * are detections, Squares hints of detectionsDash line: 3 sensitivity limit of IRAM 30m in 2h

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Correlation with Halpha

Both Edge (2001) and Salome & Combes (2003) dataSame excitation mechanisms, H shocked gas from cooling flowsor ionised by young stars formed

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Comparison between MH2 and dM/dt

dM/dt from Einstein (White et al 1997). Lines are 1%, 10%, and 100% dM/dt x 1 GyrIn blue, dM/dt (<r) ~r ~1 taken into account

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MH2 versus Mdust to be done with APEX

Mdust from IRAS (assumed 35K). Straight lines representgas-to-dust ratio of 200, 500 and 1500.Sputtering destroys dust in cluster hot gasHigher gas-to-dust ratio expected

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Abell 1795 cooling flow

Cooling time 300 Myr (Fabian et al 01)

200 Mo/yr in R < 200kpc (Ettori et al 02)

No gas below 2kev (Tamura et al 01, XMM)

60kpc H filament (Cowie et al 85)at V(cluster)Cooling wakeThe cD has V=374km/s w/o cluster

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Abell 1795: 2 new PdB fields (mosaic)

CO(1-0) 3.8 ’’ IRAM PdB CO(2-1) 1.8’’Cold gas coincident with cooling flow, not with any galaxy(Salomé & Combes 2003) z=0.06326 Cont-3mm = 7mJy

20% of the 30m fluxretrieved, 4.8 109 Mo

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CO(2-1) integrated map

Close correspondance between the CO(2-1) emission andthe H +[NII] line emission (gray scale)6cm contours van Breugel et al 1984Cold gas may have deflected the expanding radio lobes?The jet creates a hole (bubble) in the hot gas, which is compressedat the boundaries, and cools

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CO(1-0) and (2-1) kinematics

Same kinematics along thefilament than HPosition-Velocity at PA=27 deg from North-Southcentred on the cD, 5" width

CO velocity not associatedwith the central galaxy, but withthe cluster (-350km/s)

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Perseus H (WIYN) and optical (HST)

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NGC 1275 H (WIYN) and CO (IRAM)

H, Conselice 01 Salome, Combes, Edge et al 05

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Perseus Cluster

Fabian et al 2003

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Perseus cooling flow: M(H2) vs L (H

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Perseus cooling flow: CO velocitiesH CO

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RXJ0821+07CO (1-0) interferometric map

Not centered on the cD galaxy

CO (2-1)

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PdB maps of RXJ0821+07

z=0.11dM/dt ~ 30 Mo/yr

Gas shifted from the center

Could trace the coolingwake, since the centralGalaxy is not at rest

(Bayer-Kim et al 2002)

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Conclusions

Now about 23 detections, MH2 up to 1010Mo, typically 20kpccentral regions Abell 1795: CO clearly associated to the cooling wake, and not in rotation in the central galaxy Perseus: CO associated to the cooling filaments (not the merger)

The CO(2-1) closely associated to the HConfirms the global CO-H correlation

H2 masses found corresponds to what is expected from the cooling rate Cold dust to be detected, and gas-to-dust ratio checked

The AGN creates cavities in the hot gas. Cooling more efficient alongthe edges of cavities, where the CO and H are observed