Inflating Fat Bubbles in Clusters of Galaxies by Slow Wide Jets

Assaf Sternberg (did the work)

Noam Soker (speaker today)

Technion, Israel July 2008

Goal: To form ‘Fat’ Bubbles

PERSEUS IN VISIBLE AND X-RAY

Old bubble

Young bubbles

Rayleigh-Taylor instability

From Fabian and

collaborators

Cluster

Cluster

Planetary nebula

Planetary nebula

More ‘Fat’

Bubbles

From planetary nebulae we learn that there is no need for relativistic effects or strong magnetic fields

NGC 3587 Guerrero et al.

From Gorny et al .

NGC 2818

He 2-116.

NGC 3195 He 2-37.

Initial Setting

LowDensity

HighDensity

ICM in hydrostatic equilibrium

Wide Jet or

Precessing Jet

1

12

44 12

7

7750

10

2 10

2.7 10

j

j

j

v km s

M M yr

E erg s

T K

RESULTS: (1) Fat Bubbles (Assaf Sternberg PhD thesis)

The jet:

Temperature Density

44 1 1

1

10 ; 7750

5 ; 70

j j

Oj

E erg s v km s

M M yr

After 2.5 Myr

After 5 MyrAfter 5 Myr

Forward shock (ICM is

shocked)

Forward shock (ICM is

shocked)

Reverse shock (jet is shocked)

Contact discontinuity

RESULTS: (2a) Buoyant Bubbles

Evolution with gravity included. Here the density and velocity maps when the jet is shut off after10Myr activity.

Note 2: Vortex

Note 1: ICM Backflow

Note 3: a dense shell with momentum

During the inflation phase the bubble is stable (Pizzolato & Soker 2006)

Evolution of a bubble inserted by hand

After 15 Myr

After 30 Myr After 30 Myr

Jet-inflated bubble Artificial Bubble

Full evolution of ajet-inflated bubble

After 15 Myr

Instabilities

Momentum of shell leads to faster

motion

A weak shock

Note 4: mixing of hot gas with the ICM

Note 5: no instabilities

RESULTS (2b) Evolution

(Sternberg& Soker,MNRASLetter,in press)

Ripples in Perseus)Fabian et al(.

RESULTS: (3) Sound Waves: Wide jets

Density

Jets were active from to

A weak shock

Note 7: Several sound waves

0t 10t

Note 6: Complicated and changing bubbles’ shape

DensityJet was active at all times, starting at t=0.

Note 7: Several sound waves

RESULTS: (3) Sound Waves:

Precessing jets

A weak shock: Mach=1.3

SUMMARY

Slow massive jets can account for:

(1)Recycling of gas that cools from the ICM. (2) Formation of fat bubbles close to the center.(3) Allowing the bubble to rise to large distances. (4) Efficient energy transfer form bubbles to the ICM.

A realistic jet-inflation process shows that:

1) Vortices can stabilize the bubble.

2) The expanding shell around the bubble stabilizes it.

3) An efficient mixing between bubbles and the ICM.

4) One inflation episode excites several sound waves.