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

GalFRESCA 2017 Stellar feedback strongly alters the amplification and morphology of galactic magnetic fields Kung-Yi Su TAPIR, California Institute of Technology

Collaborators Prof . Philip F . Hopkins Chris Hayward Prof. Claude-André 
 Prof. Du š an Kere š Prof. Eliot Quataert Faucher-Giguère

? Magnetic Field 
 Baryonic physics Amplification

Baryonic physics Stellar Feedback 
 - FIRE 
 - Sub-grid (S&H) ? Magnetic Field 
 Amplification

Baryonic physics Stellar Feedback 
 - FIRE 
 - Sub-grid (S&H) ? Magnetic Field 
 Amplification Cooling Physics 
 - Low temperature?

Baryonic physics Stellar Feedback 
 - FIRE 
 - Sub-grid (S&H) ? Magnetic Field 
 Amplification Cooling Physics 
 - Low temperature? Star Formation

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

SMC : Small Magellanic Cloud-like dwarf MW : Milky Way-like galaxy Model Star Formation Cooling Feedback Adiabatic NO None None NoFB Yes 10-10 10 K None FIRE Yes 10-10 10 K FIRE Springel & 
 S&H Yes 10 4 -10 10 K Hernquist

Magnetic Field Morphology MW

Magnetic Field Morphology MW

Magnetic Field Morphology MW

Magnetic Field Morphology SMC

Randomness of Magnetic Field 1 . 0 SMC MW 0 . 8 ξ 1 = | h B i | / h B 2 i 1 / 2 ξ 2 = h | B | i / h B 2 i 1 / 2 B ave / B rms 0 . 6 Adiabatic 0 . 4 SH NoFB 0 . 2 FIRE 0 . 0 10 � 3 10 � 1 10 � 3 10 � 1 10 1 10 3 10 1 10 3 Density [n/cm 3 ] Density [n/cm 3 ]

Magnetic Field Amplification SMC MW 10 1 Magnetic Field [ µ G] Adiabatic log(Magnetic Field) [ µ G] 10 0 NoFB SH 10 − 1 FIRE FIRE-low 10 − 2 All Gas 10 − 3 n > 1 cm − 3 0 . 0 0 . 2 0 . 4 0 . 6 0 . 0 0 . 2 0 . 4 0 . 6 0 . 8 Time [Gyr] Time [Gyr] Magnetic fields in dense particles differ a lot

Magnetic Field Amplification SMC MW 10 1 Magnetic Field [ µ G] Adiabatic log(Magnetic Field) [ µ G] 10 0 NoFB SH 10 − 1 FIRE FIRE-low 10 − 2 All Gas 10 − 3 n > 1 cm − 3 0 . 0 0 . 2 0 . 4 0 . 6 0 . 0 0 . 2 0 . 4 0 . 6 0 . 8 Time [Gyr] Time [Gyr] Magnetic fields in dense particles differ a lot

Magnetic Field Amplification SMC MW 10 1 Magnetic Field [ µ G] Adiabatic log(Magnetic Field) [ µ G] 10 0 NoFB SH 10 − 1 FIRE FIRE-low 10 − 2 All Gas 10 − 3 n > 1 cm − 3 0 . 0 0 . 2 0 . 4 0 . 6 0 . 0 0 . 2 0 . 4 0 . 6 0 . 8 Time [Gyr] Time [Gyr] Magnetic fields in dense particles differ a lot

Turbulent & Magnetic Energy 10 13 SMC MW 10 12 Energy / Mass [erg/g] Turbulent 10 11 Magnetic 10 10 Nofb SH Fire 10 9 Fire FIRE-lo 10 8 FIRE-low 10 7 10 6 0 . 0 0 . 2 0 . 4 0 . 6 0 . 0 0 . 2 0 . 4 0 . 6 0 . 8 Time [Gyr] Time [Gyr] Magnetic energy ~ 2-6% of Turbulent Supersonic turbulent dynamo

Magnetic & Density 10 3 SMC MW 10 2 Adiabatic SH 10 1 B rms [ µ G] NoFB 10 0 FIRE Initial Condition 10 − 1 10 − 2 10 − 3 10 − 3 10 − 1 10 1 10 3 10 − 3 10 − 1 10 1 10 3 Density [n/cm 3 ] Density [n/cm 3 ] B ∝ n 2/3 - Flux freezing isotropic compression/ expansion 
 - Gravitational energy ~ Magnetic energy

Magnetic & Density 10 3 SMC MW 10 2 Adiabatic SH 10 1 B rms [ µ G] NoFB 10 0 FIRE Initial Condition 10 − 1 10 − 2 10 − 3 10 − 3 10 − 1 10 1 10 3 10 − 3 10 − 1 10 1 10 3 Density [n/cm 3 ] Density [n/cm 3 ] B ∝ n 2/3 - Flux freezing isotropic compression/ expansion 
 - Gravitational energy ~ Magnetic energy

Outflows 1 M out flow /dlogn) [M � /yr] MW SMC 0 Adiabatic S&H � 1 NoFB FIRE � 2 � 3 log(d˙ � 4 � 5 � 6 � 4 � 2 0 2 4 � 6 � 4 � 2 0 2 4 Density [n/cm 3 ] Density [n/cm 3 ] 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 ∝ n 2/3 Flux freezing isotropic compression/ expansion Gravitational energy ~ Magnetic energy

Divergence Cleaning Numerical error of builds up r · B S = S Powell + S Dedner Powell 8 wave 
 Dedner 
 - Transport and Damp -Subtract the divergence     0 0 0 B         B · ( r ψ ) = � v · B = �r · B         v r ψ     ( r · B ) ρ c 2 h + ρψ / τ 0 back Powell (1999) Dedner et al. (2002)

back Turbulent energy

back Turbulent energy 10 Kpc Particles in the gas disk 1Kpc

back Turbulent energy 10 Kpc Particles in the gas disk Cut into annuli 1Kpc

back Turbulent energy 10 Kpc Particles in the gas disk Cut into annuli Fixed particle number 1Kpc

back Turbulent energy 10 Kpc Particles in the gas disk Cut into annuli Fixed particle number Subtract V rot 1Kpc

back Turbulent energy 10 Kpc Particles in the gas disk Cut into annuli Fixed particle number Subtract V rot Subtract wind 1Kpc

back Turbulent energy 10 Kpc Particles in the gas disk Cut into annuli Fixed particle number Subtract V rot Subtract wind Cut into rings 1Kpc

back Turbulent energy 10 Kpc Particles in the gas disk Cut into annuli Fixed particle number Subtract V rot Subtract wind Cut into rings Same particle number 1Kpc

back Turbulent energy 10 Kpc Particles in the gas disk Cut into annuli Fixed particle number Subtract V rot Subtract wind Cut into rings Same particle number Cut into cells with 
 1Kpc 15 particles

back Turbulent energy 10 Kpc Particles in the gas disk Cut into annuli Fixed particle number Subtract V rot Subtract wind Cut into rings Same particle number Cut into cells with 
 1Kpc 15 particles Subtract V group 
 and other outflow

back Turbulent energy 10 Kpc Particles in the gas disk Cut into annuli Fixed particle number Subtract V rot Subtract wind Cut into rings Same particle number Cut into cells with 
 1Kpc 15 particles Subtract V group 
 E Turbulent = Remaining kinetic energy and other outflow