Stellar feedback strongly alters the amplification and morphology of - - PowerPoint PPT Presentation

strongly alters the amplification and morphology of galactic magnetic fields Stellar feedback

Kung-Yi Su TAPIR, California Institute of Technology GalFRESCA 2017

Collaborators

Prof . Philip F . Hopkins Chris Hayward

• Prof. Claude-André 


Faucher-Giguère

• Prof. Dušan Kereš
• Prof. Eliot Quataert

Magnetic Field
 Amplification

?

Baryonic physics

Stellar Feedback


• FIRE

• Sub-grid (S&H)

Magnetic Field
 Amplification

?

Baryonic physics

Stellar Feedback


• FIRE

• Sub-grid (S&H)

Cooling Physics


• Low temperature?

Magnetic Field
 Amplification

?

Baryonic physics

Stellar Feedback


• FIRE

• Sub-grid (S&H)

Cooling Physics


• Low temperature?

Star Formation

Magnetic Field
 Amplification

?

Baryonic physics

GIZMO + MHD (Hopkins and Raives 2016) Stellar Feedback FIRE Stellar Feedback


• SNe, Stellar Winds, Photo-ionization, Photo-

electric heating, Radiation pressure Sub-grid


• Springel and Hernquist (2003)

• Effective equation of state

• Implicitly 2 phase ISM

Model Star Formation Cooling Feedback Adiabatic NoFB FIRE S&H NO Yes Yes Yes None 10-1010 K 10-1010 K 104-1010 K None None FIRE Springel &
 Hernquist SMC : Small Magellanic Cloud-like dwarf MW : Milky Way-like galaxy

MW Magnetic Field Morphology

MW Magnetic Field Morphology

MW Magnetic Field Morphology

SMC Magnetic Field Morphology

Randomness of Magnetic Field

103 101 101 103

Density [n/cm3]

0.0 0.2 0.4 0.6 0.8 1.0

Bave / Brms

SMC

103 101 101 103

Density [n/cm3]

MW

ξ1 = |hBi|/hB2i1/2 ξ2 = h|B|i/hB2i1/2 Adiabatic SH NoFB FIRE

Magnetic Field Amplification

0.0 0.2 0.4 0.6 0.8

Time [Gyr]

log(Magnetic Field) [µG]

MW

Adiabatic NoFB SH FIRE FIRE-low All Gas n > 1 cm−3

0.0 0.2 0.4 0.6

Time [Gyr]

10−3 10−2 10−1 100 101

Magnetic Field [µG]

SMC

Magnetic fields in dense particles differ a lot

Magnetic Field Amplification Magnetic fields in dense particles differ a lot

0.0 0.2 0.4 0.6 0.8

Time [Gyr]

log(Magnetic Field) [µG]

MW

Adiabatic NoFB SH FIRE FIRE-low All Gas n > 1 cm−3

0.0 0.2 0.4 0.6

Time [Gyr]

10−3 10−2 10−1 100 101

Magnetic Field [µG]

SMC

Magnetic Field Amplification Magnetic fields in dense particles differ a lot

0.0 0.2 0.4 0.6 0.8

Time [Gyr]

log(Magnetic Field) [µG]

MW

Adiabatic NoFB SH FIRE FIRE-low All Gas n > 1 cm−3

0.0 0.2 0.4 0.6

Time [Gyr]

10−3 10−2 10−1 100 101

Magnetic Field [µG]

SMC

Turbulent & Magnetic Energy Magnetic energy ~ 2-6% of Turbulent Supersonic turbulent dynamo

0.0 0.2 0.4 0.6 0.8

Time [Gyr]

MW

Turbulent Magnetic Nofb SH Fire FIRE-low

0.0 0.2 0.4 0.6

Time [Gyr]

106 107 108 109 1010 1011 1012 1013

Energy / Mass [erg/g]

SMC

Fire FIRE-lo

10−3 10−1 101 103

Density [n/cm3]

10−3 10−2 10−1 100 101 102 103

Brms [µG] SMC

10−3 10−1 101 103

Density [n/cm3]

MW

Adiabatic SH NoFB FIRE Initial Condition

Magnetic & Density

B ∝ n2/3 - Flux freezing isotropic compression/ expansion


• Gravitational energy ~ Magnetic energy

10−3 10−1 101 103

Density [n/cm3]

10−3 10−2 10−1 100 101 102 103

Brms [µG] SMC

10−3 10−1 101 103

Density [n/cm3]

MW

Adiabatic SH NoFB FIRE Initial Condition

Magnetic & Density

B ∝ n2/3 - Flux freezing isotropic compression/ expansion


• Gravitational energy ~ Magnetic energy

6 4 2 2 4

Density [n/cm3]

5 4 3 2 1 1

log(d˙ Mout flow /dlogn) [M/yr]

MW

6 4 2 2 4

Density [n/cm3]

SMC

Adiabatic S&H NoFB FIRE

Outflows Feedback driven >> Magnetic driven

Summary

Sub-grid model (effective EOS) Reasonable result in gas with lower density Worse dense gas More ordered large scale magnetic field B ∝ n2/3 Flux freezing isotropic compression/ expansion Gravitational energy ~ Magnetic energy

Numerical error of builds up Powell 8 wave


• Subtract the divergence

S = SPowell + SDedner

= r · B       B v · B v       Dedner


• Transport and Damp

=       B · (rψ) rψ (r · B)ρc2

h + ρψ/τ

      r · B

Dedner et al. (2002) Powell (1999)

Divergence Cleaning

back

Turbulent energy

back

Turbulent energy

Particles in the gas disk

10 Kpc 1Kpc

back

Turbulent energy

Cut into annuli Particles in the gas disk

10 Kpc 1Kpc

back

Turbulent energy

Fixed particle number

Cut into annuli Particles in the gas disk

10 Kpc 1Kpc

back

Turbulent energy

Fixed particle number

Cut into annuli

Subtract Vrot

Particles in the gas disk

10 Kpc 1Kpc

back

Turbulent energy

Fixed particle number

Cut into annuli

Subtract Vrot

Subtract wind Particles in the gas disk

10 Kpc 1Kpc

back

Turbulent energy

Fixed particle number

Cut into annuli

Subtract Vrot

Subtract wind Cut into rings Particles in the gas disk

10 Kpc 1Kpc

back

Turbulent energy

Fixed particle number

Cut into annuli

Subtract Vrot

Subtract wind Cut into rings

Same particle number

Particles in the gas disk

10 Kpc 1Kpc

back

Turbulent energy

Fixed particle number

Cut into annuli

Subtract Vrot

Subtract wind Cut into rings

Same particle number

Cut into cells with
 15 particles

Particles in the gas disk

10 Kpc 1Kpc

back

Turbulent energy

Fixed particle number

Cut into annuli

Subtract Vrot

Subtract wind Cut into rings

Same particle number

Cut into cells with
 15 particles

Subtract Vgroup 
 and other outflow

Particles in the gas disk

10 Kpc 1Kpc

back

Turbulent energy

Fixed particle number

Cut into annuli

Subtract Vrot

Subtract wind Cut into rings

Same particle number

Cut into cells with
 15 particles

Subtract Vgroup 
 and other outflow

Particles in the gas disk

10 Kpc 1Kpc

ETurbulent = Remaining kinetic energy

back