Massive molecular gas flows and AGN feedback in galaxy clusters

Transcription

1 Massive molecular gas flows and AGN feedback in galaxy clusters CO(3-2) Helen Russell (Cambridge) Brian McNamara (Waterloo), Andy Fabian (Cambridge), Paul Nulsen (CfA), Michael McDonald (MIT), Alastair Edge (Durham), Francoise Combes (Paris), Philippe Salomé (Paris), Jeremy Sanders (MPE) and the SPT collaboration

2 Outline Introduction Radiative cooling in galaxy clusters AGN feedback Results ALMA observations of molecular gas in central cluster galaxies Massive extended filaments, smooth velocity gradients AGN-driven gas outflows Direct uplift of molecular clouds or cooling in situ? Conclusions

3 X-ray surface brightness peaks in cluster cores X-ray radiative cooling time 100 kpc Chandra X-ray 100 kpc Lewis et al. 2003, Allen et al Cooling time (Gyr) Optical Voigt & Fabian 2004 Radius (kpc) M per year gas cooling?

4 Radio jets heat cluster gas Searches for vast reservoir of molecular gas find less than 10% of that expected (Edge '01, Salomé + Combes '03) residual cooling AGN heating replaces radiative losses feedback loop Truncates galaxy growth, keeps ellipticals red and dead, M-σ relation Optical, X-ray, Radio Pcav (1042 ergs-1) Heating 200 kpc LX(<rcool) (1042 ergs-1) MS0735, McNamara et al Cooling Rafferty et al. 2006; Birzan et al. 2004; Fabian 2012

5 What is the role of molecular gas in feedback? BCGs in cool core clusters are rich in molecular gas (Edge 2001, Salomé & Combes 2003) Chandra: energy output ALMA: fuelling? Origin of molecular gas in BCGs? Is molecular gas fuelling feedback? Does radio-jet feedback operate on molecular clouds?

6 Extended filaments of molecular gas Massive filaments each ~ a few x M PKS0745 and 3 15 kpc long Phoenix CO(3-2) kpc Russell et al. 2016, submitted

7 Filaments consist of many GMCs CO(2-1) absorption features with ~ 5 km/s linewidth typical of GMC and infalling velocity km/s A2597 Flux (mjy) NGC5044 Velocity (km/s) David et al Tremblay et al. 2016

8 Low velocities and low dispersions PKS0745 PKS0745: Modest velocities ±100 km/s, narrow FWHM ~100 km/s Gas not settled in gravitational potential Velocity map Beam size: 0.3 arcsec, 0.5 kpc Velocity dispersion Russell et al. 2016

9 Smooth velocity gradients along filaments A1795: Low velocities at small radii Highest velocities at largest radii Outflow?

10 Highest velocities at largest radii A1835: 1010 M molecular flow at km/s extending to 10kpc McNamara et al A1835

11 Phoenix cluster: ordered gas flow to centre Smooth velocity gradients and low FWHM in filaments Velocity gradient across nucleus with much higher FWHM Velocities too low for free fall in gravitational potential CO(3-2) Russell et al. submitted

12 Molecular gas not settled in the gravitational potential Massive filaments, low velocities merger origin is unlikely Low velocities compared to stars filaments not supported by rotation Highest velocities at large radii outflow? Perseus: Hα CO detections on Hα image Fabian et al. 2003; Conselice et al. 2001; Lim et al. 2008; Salome et al. 2011

13 Molecular gas filaments extend toward radio bubbles PKS0745: massive filaments drawn up underneath X-ray cavities and radio lobes 0.3 arcsec 0.5 kpc Russell et al Sanders et al. 2014

14 A1835: gas flow drawn up around the X-ray cavities Gas filaments drawn up around radio bubble Interaction with cold gas in radio-mode feedback A1835 CO(1-0) 2kpc 6.7 kpc 1.7 arcsec McNamara et al X-ray cavities

15 Phoenix cluster: filaments encase cavities Phoenix hosts a ~600 M /yr starburst and a 'transition' AGN bright in both X-ray/optical and radio 3 x 1010M of molecular gas total with half in filaments around radio bubbles HST CO(3-2) 30 kpc cavity positions McDonald + SPT collaboration 2012 Russell et al. submitted

16 Direct uplift of molecular gas clouds or cooling in situ? Molecular gas structure shaped by radio bubble expansion PKS0745 Direct uplift of molecular gas clouds? Pcav ~ erg/s High coupling efficiency required Rapid cooling of uplifted thermally unstable low entropy gas? Molecular gas coincident with soft X-ray Dust lanes Phoenix Phoenix

17 Conclusions Molecular gas structure shaped by radio bubble expansion Massive M filaments drawn up around and beneath radio bubbles Molecular emission lines are narrow Extended filaments, ordered velocity structure Gas not settled in gravitational potential Circulation flow Radio bubbles supply large-scale heating to stabilise cluster atmospheres and lift gas in their wakes PKS0745 Phoenix