Magnetic Jets and Lobes in Cosmological MHD

Hui Li Los Alamos National Laboratory

NSF/DOE Center for Magnetic Self-Organization (CMSO)

Collaborators:

H. Xu, D. Collins, S. Li, M. Morman

Overview of Observations and Magnetic Jet Model Results on 3D MHD Jet/Cluster Simulations Results on Cosmological MHD Jet/Cluster Simulations

Papers and Posters

1) Basic model: Li et al. ApJ, 2006

2) Jets in Static Clusters: Nakamura, Li, Li, ApJ, 2006, 2007

3) Comparison w. X-ray Bubbles: Diehl et al. ApJ, 2008

4) Comparison w. Herc A Observ: Nakamura et al. ApJ, 2008

5) Cosmological MHD Jet+Cluster Simulation: Xu et al. ApJL, 2008

6) Long-time evolution of magnetic bubble: Liu et al. ApJL, submitted

Both Steven Diehl and Hao Xu have posters at this meeting.

We are also looking for a postdoc in this area.

Hydra A (Wise et al.)

Jets and Lobes in Galaxy Clusters :Effects of ICM Dynamics ?

MS0735.6+7421 (McNamara et al.)

~ 400 kpc

~ 1 Mpc

Perseus (Fabian et al.)

~ 250 kpc

Leahy et al.(1996)

disk

Poloidal flux: ~ 104 (1014)2 ~ 1032 (G cm2) Toroidal flux: ~ (t) G cm2) Current: I ~ B R ~ 1018 A Mag. energy injection rate: dEmag/dt = Iz V - Ploss

Expansion: Iz(r,t), (r,t), and Ploss(r,t).

BH

Li et al. (2006)

Astrophysical Jets: Engine and Injection

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λ =I polΨpol

r0QuickTime™ and aTIFF (LZW) decompressor

are needed to see this picture.

Ipol

r0

Li et al. 2006; Nakamura, Li, Li 2006; 2007

Li (2008)

With Both Magnetic and Kinetic Injections

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are needed to see this picture.

Ipol

r0

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Magnetic field and Momentum Injection :

Poloidal Flux (Br and Bz) : Ψinj = r2 exp(−r2 − k 2z2)

Toroidal Field (and poloidal current) : Bφ inj =αΨinj /r,

Magnetic Flux (energy) injection : ∂B

∂t= Binj(r,z) • γB (t)

Kinetic energy injection : ∂(ρv)

∂t= vinj(r,z) • γ v (t)

3D MHD SimulationsCluster: isothermal, hydrostatic (initially)

T = 4 keV, nc = 0.01 (1/cm3), Rc = 40 kpc; = 0.5

Jets in Static Clusters:

injection time: 40 Myr

injection magnetic energy: ~ 3x1060 ergs (~2.5x1045 ergs/s)

mass injection rate: < Msun / yr

Magnetic field and current distribution(as kinetic energy injection increases…)

EB = 2.6x1060 ergsEk < 2.6x1056 ergs

EB = 1.8x1060 ergsEk = 0.7x1060 ergs EB = 1.6x1060 ergs

Ek = 2.3x1061 ergs

Run A Run B Run C

Effects of Flows: StabilizationRun FRun E

Alfven Speed (run F)

Alfven speed (run E)

Flow Speed (run F)

Flow Speed (run E)

Radius

Vel

ocit

y

Sub-Alfvenicwith shear Supersonic

Azimuthally averaged velocity profile at z=3

Run E: without Ek injection Run F: with Ek injection

Comparison of Energy Evolution

Einj = EBinj

Einj=EBinj+EKinj

EB EB

Eth

Eth

EK

EKEg

Eg

Magnetic/Thermallog10 (eB/eth)

Magnetic/Kineticlog10 (eB/ek)

Run F: Jets/Lobes are mostly magnetically dominated

Estimating Magnetic Fields and Energy Density

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Bφ ∝IzR

,

eB ∝1

R2,

EB ∝ ln(R /R0)

Rlobe

Measuring B: could be small in the main volume.

But magnetic energy containedin the central region is a sizablefraction of the total lobe.

Analysis of 64 Bubbles in 32 ClustersSee Poster by Diehl (Diehl et al. 2008)

magnetic

HydroAdiabatic expansion

Cosmology Ideal-MHD Code( )

( )

( )

velocitypeculiar proper :v pressures; density, comoving :B

v BBvB

vBBvv

vBBvvv

v

2

,,

212

1,

2

11

2

112

2

1

1

2

1)(

01

2

22

2

g

g

g

g

P

BPE

a

a

at

Ba

a

aEa

aBPE

at

E

aa

aBP

at

at

ρ

γρ

ρ

ρρρρ

ρρ

+−

+=−××∇=∂

∂

+Φ∇•−−=⎥⎦

⎤⎢⎣

⎡•−⎟

⎠

⎞⎜⎝

⎛++•∇+

∂

∂

Φ∇−−=⎥⎦

⎤⎢⎣

⎡−++•∇+

∂

∂

=•∇+∂

∂

•

••

•

Xu et al. (2008, method paper)

• Developed AMR+MHD and implemented in ENZO code.

• ENZO AMR+Hydro simulation:

h=0.7, m=0.3, b=0.026, λ=0.7, 8=0.928

• Volume: 256 Mpc/h

• Initial 1283 root grid from

z=30, followed with 8 level

refinements (~8kpc/h)

for magnetic fields.

Cosmological AMR+MHD Simulation(see H. Xu’s poster)

Cluster formation with an AGN feedback (Xu et al. 2008)

X-rayIntensity

QuickTime™ and ampeg4 decompressor

are needed to see this picture.

Magnetic Energy Evolution

Lobes are magnetically dominated

Heating the Cluster Core Region(see Hao Xu’s poster)

Change of inflow mass of clusters with and without AGN injection

T=36 Myr T=156 Myr

T=336 Myr T=670 Myr

Magnetic jet input at high redshiftMagnetically dominated jet input at a halo at z=3size: 80 Mpc comovingInjection B fields strength: 40 microgauss Halo properties:Rvir = 0.248462 (Mpc)Mvir = 3.04303e+13 (M_solar)Mvir (gas) = 1.51376e+12 (M_solar) Mvir (dm) = 2.89165e+13 (M_solar)

T=108Myr

T=228Myr

T=348Myr

T=528Mry

T=648Myr

T=768Myr

T=1.02Gyr

T=1.38Gyr

T=2.10Gyr

T=2.82Gyr

Summary Jets/lobes as magnetically dominated system with large current

“Flaring”/Lobe formation related to background ICM pressure profile (coupled with 3D MHD instability)

Lobe size determined by balance between external pressure and total current

Magnetic energy is gradually converted to thermal and kinetic energies of the jet/lobes

Morphology of jet/lobe is heavily influenced by background ICM dynamics, though magnetic fields crucial in maintaining the integrity of jets/lobes

Relic evolution, leading to magnetization of ICM/IGM