Probing the Dynamics of Galaxy-Gas Interactions in Groups and Clusters with

Chandra and XMM-Newton

Marie MachacekSmithsonian Astrophysical Observatory

IGM Workshop 3/8/2005

Thanks to my collaborators

Christine Jones

William R. Forman

Paul Nulsen

Ralph Kraft

Alexey Vikhlinin

Maxim Markevitch

Liviu Stirbat

Galaxy-IGM Interactions in Three Systems

• Elliptical NGC 1404 Fornax Cluster kT = 1.5 keV Transonic ram-pressure stripping

• Elliptical NGC 4552 Virgo Cluster kT = 2.2 keV Supersonic ram-pressure stripping

• Spiral NGC 6872 Pavo Group kT = 0.5 keV High velocity encounter

NGC 1404 in Fornax

Dosaj et al. 2002 ; Scharf et al. 2004; Machacek et al. 2005

NGC 1399 19 Mpc

Chandra0.3-2 keV134.3 ks

NGC1404

Rp = 54 kpc

Surface Brightness Map

Temperature Map

Tg = 0.55-0.02+0.01 keV

A = 0.7-0.1+0.7 Zs

Model Assumptions

• N1404 & N1399 in same plane

- r ~ rp : stripped tail ICM dense

- sharp edge inclination angle not large

• N1404

- isothermal sphere

- density ng r-

• Surface brightness jump (gng2/cnc

2)

Vikhlinin et al. 2001; Mazzotta et al. 2001

Surface Brightness Profile

1.54

=0.5

re=7.64 kpc0.3, rc=395”

NGC 1404’s Transverse Velocity

Tg/Tc = 0.36ng/nc = 6.0pg/pc = 2.1M1 ~ 1.0v = 657 km/svr = 450 km/s*

vt = 478 km/s ~ 43˚

*Drinkwater et al. 2001

Pressure ratio vs Mach Number

NGC 4552 in Virgo

Chandra54.4 ks0.5-2 keV

Machacek et al. 2005

Surface Brightness Profile

r1 = 1.29 kpc

r2 = 3.12 kpc

=1.29

Surface Brightness Profile

r1 = 1.29 kpc

r2 = 3.12 kpc

T1 = 0.61 keVT2 = 0.44 keVAg = 0.6±0.2 Zs

Tc = 2.2 keV

NGC 4552’s Transverse Velocity

Tg/Tc = 0.2ng/nc = 37 ± 5pg/pc = 7.3 ± 1.1M1= 2.1 ± 0.2v = 1646 km/svr = -968 km/s*

vt = 1331 km/s ~ 36˚ ± 3˚

Pressure ratio vs Mach Number

Tail Properties

• T = 0.57+0.06-0.1 keV

• n ~ 0.006 cm-3 >> nc

• p ~ a few pICM

• length ~ 10 kpc • bowed

Shock Model for Inner Rings

Mach = 1.7 t = 1.32 Myr

Emech = 2.4 1055fv ergs Lmech = 5.8 1041fv ers/s Lmech - Lradio 6.4 1041 ergs/s

Birzan et al. 2004

Tidal InteractionsNGC 6872/ IC 4970

VLT-ANTU+FORS1 ESO Top 20 images

NGC 6872 in PavoD = 53.5 Mpc vr = 849 km/s*

*Martimbeau & Huchra CfA Redshift Survey 2004

Strong Interaction with Pavo XMM pn+mos0.5-2 keV32.2 ks

Machacek et al. 2005 astro-ph 0411286v2

Trail Properties

• Hot T ~1 kev ~2TIGM

• Dense n ~ 1.7nIGM

• Low abundance

A ~ 0.2 ± 0.1 Zs

• Large extent

~ 67 90 kpc

Trail Formation Models• Tidal Stripping - distortions of other tracers ?• Ram Pressure Stripping

- T high? A low? n < 2 nICM

- not like NGC 4552!• Bondi-Hoyle Gravitional Focusing• Turbulent Viscous Stripping

Bondi Gravitational Focusing

Mach ~ 3

/ flat long trail

no large central peak

large gravitating halo ?

vcirc ~ ?

a = 20 kpc ?

sufficient heating ?

Tad ~ 1.4 TIGM

For NFW profile

Turbulent Viscous Stripping

v ~ 1300 km/s ~ 40

Stripping Rate

Energy

Extent +Adiabatic expansion

v = vr / sin

Signatures in the Trail

• Filaments, streamers

gas? stars? dust?• Abundance

galaxy, IGM or mix?• T & n profile

thermalization region?

cools, broadens & dims?

Conclusions

• Constrain 3-D motion of galaxy

• Show stripping processes in action

• Reveal interactions previously overlooked

• Differentiate between different stripping processes

X-ray Observations of Edges, Tails and Trails