1. Molecular gas in cooling flows Interplay with AGN and starbursts
Ph. Salomé & F. Combes
APEX workshop
3- February 2006

2. 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 detected
Edge (2001) Salomé & Combes (2003) detected galaxies in CO
Results from Chandra & XMM: cooling flow self-regulated
Re-heating process, feedback due to the active nucleus or black
Hole: schocks, jets, acoustic waves, bubbles...

3. Sound waves in Perseus with Chandra
Fabian et al 2003
NGC 1275=Abell 426
Mechanical energy much
larger than Lbol
(Binney & Tabor 1995,
Churazov et al 2002)

4. Detection of CO with IRAM-30m
CO survey
Selected on dM/dt
and Ha
6-10 detections
among 32 galaxies
Masses between Mo
Mgas versus z,
Stars * are detections,
Squares hints of detections
Dash line: 3s sensitivity limit
of IRAM 30m in 2h

5. Correlation with Halpha
Both Edge (2001) and Salome & Combes (2003) data
Same excitation mechanisms, Ha shocked gas from cooling flows
or ionised by young stars formed

6. Comparison between MH2 and dM/dt
dM/dt from Einstein (White et al 1997). Lines are
1%, 10%, and 100% dM/dt x 1 Gyr
In blue, dM/dt (<r) ~ra a ~1 taken into account

7. MH2 versus Mdust  to be done with APEX
Mdust from IRAS (assumed 35K). Straight lines represent
gas-to-dust ratio of 200, 500 and 1500.
Sputtering destroys dust in cluster hot gas
Higher gas-to-dust ratio expected

8. 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 Ha filament (Cowie et al 85)
at V(cluster)
Cooling wake
The cD has V=374km/s w/o cluster

9. Abell 1795: 2 new PdB fields (mosaic)
20% of the 30m flux
retrieved, Mo
CO(1-0)  ’’ IRAM PdB CO(2-1) 1.8’’
Cold gas coincident with cooling flow, not with any galaxy
(Salomé & Combes 2003) z= Cont-3mm = 7mJy

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

11. CO(1-0) and (2-1) kinematics
CO velocity not associated
with the central galaxy, but with
the cluster (-350km/s)
Same kinematics along the
filament than Ha
Position-Velocity at
PA=27 deg from North-South
centred on the cD, 5" width

12. Perseus Ha (WIYN) and optical (HST)

13. NGC 1275 Ha (WIYN) and CO (IRAM)
Ha, Conselice 01
Salome, Combes, Edge et al 05

14. Perseus Cluster
Fabian et al 2003

15. Perseus cooling flow: M(H2) vs L (Ha)

16. Perseus cooling flow: CO velocities
Ha CO

17. RXJ0821+07 CO (1-0) interferometric map Not centered on the cD galaxy

18. PdB maps of RXJ0821+07 z=0.11 dM/dt ~ 30 Mo/yr
Gas shifted from the center
Could trace the cooling
wake, since the central
Galaxy is not at rest
(Bayer-Kim et al 2002)

19. Conclusions Now about 23 detections, MH2 up to 1010Mo, typically 20kpc
central 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 Ha
Confirms the global CO-Ha 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 along
the edges of cavities, where the CO and Ha are observed