Deep Chandra and XMM-Newton Observations of NGC 4472

R. P. Kraft, S. W. Randall, W. R. Forman, P. E. J. Nulsen, C. Jones, A. Bogdan, M. J. Hardcastle, E. Hallman, T.

Maccarone, T. Joseph, S. Raychaudhury, D. Evans, G. Sivakoff, C. Sarazin (+ M. Machacek, J. ZuHone, R.

Johnson)

SAO/University of Hertfordshire/Southampton University/Birmingham University/University of Alberta/University of Virginia29JUN11 - Presentation at ‘The X-ray Universe 2011’ conference

Introduction – Cluster and Group Mergers – Potpourri of Gas Dynamics

• Merging is central to the hierarchical formation of structure paradigm

• Chandra and XMM-Newton have studied large number of cluster and group mergers– Shocks/supersonic infall (e.g. Bullet Cluster)– Cold fronts/ram pressure stripping (e.g.

Fornax cluster, M86)– Sloshing (e.g. Abell 1795, NGC 7618/UGC

12941)

Shocks

Cold FrontsSloshing

Introduction – Cluster and Group Mergers – Potpourri of Gas Dynamics

• Merging is central to the hierarchical formation of structure paradigm

• Chandra and XMM-Newton have studied large number of cluster and group mergers– Shocks/supersonic infall (e.g. Bullet Cluster)– Cold fronts/ram pressure stripping (e.g.

Fornax cluster, M86)– Sloshing (e.g. Abell 1795, NGC 7618/UGC

12941)

Shocks

Cold FrontsSloshing

Entropy, temperature, and emission weighted projected temperature from cold front simulation (Heinz et al. 2003)

Introduction – What is NGC 4472 and why do we care

• NGC 4472 is most optically luminous galaxy in local Universe

• Member of Virgo cluster (d=17 Mpc, 1”=80 pc)

• Lies at virial radius (1.35 Mpc) of the Virgo cluster

• MSMBH=6x108 M

• Best example of group/cluster merger in local Universe for detailed study– Proximity– Luminosity– Gas temperature (<1.5 keV)

• Chandra LP (380 ks total) approved in last AO

• Received data 3 months ago

ROSAT mosaic of Virgo cluster (Bohringer et al. 1995)

Previous X-ray Observations (Biller et al. 2004 and Kraft et al. 2011)

100 ks XMM-Newton (PI: T. Maccarone) – MOS1+2 in 0.5-1.0 keV band

Direction of infall M87

Broadband Overview•380 ks Chandra/ACIS-S•Smoothed (s=1.5’’), exposure corrected•0.5-2.0 keV band•Point sources removed

Features of Interest•Multiple Surface Brightness Discontinuities•Filamentary Arms Around Radio Bubbles + cavities•Large scale X-ray filaments to the E and SW of the nucleus (seen by XMM)

Narrower Bands

0.7-0.9 keV 1.1-1.5 keV

Core Region

0.5-2.0 keV image with radio contours overlaid

Temperature map with radio contours overlaid

•Gas core is clearly sloshing•Complex temperature structure aligned with radio lobes - Uplift

9.7 kpc

Radio Outburst

•Density jump implies M=1.1-1.2•Pmech=1.3x1057 ergs

•Significant energy in shocks+uplift (e.g. filaments in Hyd A)

Shock visible in harder band

Similar to shocks in M87

1.1-1.5 keV band, smoothed exposure corrected

Temperature map (1000 counts per cell)

On scales of tens of kpc, hot gas distributed asymmetrically around nucleus

Cold filaments to the E and SW of the core – relic buoyant radio bubble?

Origin? Related to merger process? Sloshing?

Looks much different than Abell 3667 and the simulations of Heinz et al. (2003)

Temperature map (1000 counts per cell)

On scales of tens of kpc, cold gas is distributed asymmetrically around nucleus

Cold filaments to the E and SW of the core – relic buoyant radio bubble?

Origin? Related to merger process?

Looks much different than Abell 3667 and the simulations of Heinz et al. (2003)

Abell 3667 (Vikhlinin et al. 2001)

Discontinuities in large scale gaskBT=0.96±0.02 keVZfe=0.47±0.04Zsi=0.68±0.07

kBT=1.04±0.02Zfe=0.36±0.04Zsi=0.56±0.07

Small temperature jump across discontinuity – significant abundance jump

Evidence of flow separation (?) or just sloshing

Discontinuities in large scale gaskBT=0.96±0.02 keVZfe=0.47±0.04Zsi=0.68±0.07

kBT=1.04±0.02Zfe=0.36±0.04Zsi=0.56±0.07

Small temperature jump across discontinuity – significant abundance jump

Evidence of flow separation (?) or just sloshingRetail≈1000 assuming

Spitzer type viscosity

Infall into the Virgo Cluster

M87

M49

What is NGC 4472 falling into?

Infall velocity between 1200 and 2500 km s-1

Could this be the WHIM? Virgo cluster gas falling back into NGC 4472 group potential?

Infall into the Virgo Cluster

M87

M49

What is NGC 4472 falling into?

Infall velocity between 1000 and 2500 km s-1

Could this be the WHIM?

NGC 4522 – small spiralRPS -> 4000 km s-1!! (Kenney et al. 2004)

NGC 4649 group created sloshing structures in M87 (Rodiger et al.2011)

Preliminary Conclusions and Future Work

• NGC 4472 clearly not a ‘classical’ cold front• Disentangling everything will not be trivial!• Detected a weak shock around radio lobe +

evidence up significant uplift• Multiple contact discontinuities in gas tail from

merger – flow separation (?)• Large-scale mosaic with XMM-Newton from

NGC 4472 to NGC 4261 needed!• Need better radio data!

Hydrodynamic Simulation of Group/Cluster Merger (from John ZuHone) and Cold Front (Heinz et al. 2003)

Entropy, temperature, and emission weighted projected temperature from cold front simulation (Heinz et al. 2003)

Temperature slice of supersonic merger

Nuclear Outburst and Feedback• Feedback now a central theme

in astrophysics – particularly relevant to clusters and galaxies

• Many Chandra studies of supersonic inflation of radio lobes – Cen A, M87, Per A, Her A, etc.

• Suppress cooling flows, control star formation, distribute metals

• Less dramatic outbursts more common and probably more important!

Cen A (Kraft et al. 2008)

M87 (Forman et al. 2005)

Active Nucleus

0.5-2.0 keV image with radio contours overlaid

Temperature map with radio contours overlaid

•n0=0.2 cm-3, kBT=700 eV•Pbondi=5x1044 ergs s-1,Pmech=5x1042 ergs s-1, Lx= 2x1038 ergs s-1

•Complex temperature structure of gas makes it difficult to study Bondi flow

9.7 kpc

Compact Binary PopulationDisk BB Temperature versus Lx (curves from Gierlinski & Done 2004)•Filled squares – NGC 4472 (Joseph et al. in preparation)•Crosses – NGC 3379 (Brassington et al. 2009)•Dozens/hundreds of points on this graph (Cen A, NGC 4649, M31, etc.)