Accretion, Buoyancy, and Chaos: ABCs of Galaxy Formation Ben Keller - - PowerPoint PPT Presentation

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Accretion, Buoyancy, and Chaos: ABCs of Galaxy Formation Ben Keller - - PowerPoint PPT Presentation

Nov 23, 2023 158 likes •615 views

Accretion, Buoyancy, and Chaos: ABCs of Galaxy Formation Ben Keller Universitt Heidelberg Diederik Kruijssen, James Wadsley, Samantha Benincasa, Hugh Couchman, Liang Wang Outfmows, Buoyancy, and Chaos: OBCs of Galaxy Formation Ben Keller

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Accretion, Buoyancy, and Chaos: ABCs

  • f Galaxy Formation

Ben Keller Universität Heidelberg Diederik Kruijssen, James Wadsley, Samantha Benincasa, Hugh Couchman, Liang Wang

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SLIDE 2

Outfmows, Buoyancy, and Chaos: OBCs

  • f Galaxy Formation

Ben Keller Universität Heidelberg Diederik Kruijssen, James Wadsley, Samantha Benincasa, Hugh Couchman, Liang Wang

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MUGS2: 18 L* Galaxies

  • Cosmological zoom-in simulations, run using

GASOLINE2 (Wadsley+ 2017), in a WMAP3 cosmology

  • Initial conditions identical to MUGS (Stinson+ 2010),

run with “classic” SPH and blast-wave feedback

  • Virial Masses range from 3.7x1011 to 2.1x1012Msun
  • Variety of merger histories, spin parameters
  • 320pc softening, baryon mass resolution of

2.2x105Msun

Keller+ 2016

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MUGS2: 18 L* Galaxies

Keller+ 2016

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Feedback Models Matter!

  • 4 test cases:

– No Feedback – Blastwave (Stinson+ 2006)

feedback

– Superbubble Feedback – Superbubble Feedback 2X Energy

  • g1536

– 8x1011 Msun virial mass – Last major merger at z=4 – Equal SN energy for Blastwave

and Superbubble

– Details in Keller+ 2015

Keller+ 2015

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SLIDE 7

Superbubble Feedback

  • Hot bubble is heated

by multiple SN

  • As bubble expands,

forms a cold & radiative shell

  • Shell is evaporated by

thermal conduction

∂ M B ∂t = 4 πμ 25 k B κ0T

5/2 A B

Keller+ 2014

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SLIDE 8

Correct Stellar Mass, Small Bulge

Stellar Mass Evolution Matches Behroozi+ 2012 abundance matching Flat rotation curve == no major bulge component (B/T ratio of 0.09 vs. 0.46, MW B/T ~0.14) Halo Mass Stellar Mass Keller+ 2015

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SLIDE 9

Superbubbles drive outfmows well

Keller+ 2015

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High-z outfmows prevent bulges, preserve disks

Keller+ 2015

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High-z outfmows prevent bulges, preserve disks

Bulge Forming Gas Disk Forming Gas

Keller+ 2015

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SLIDE 12

Can Supernovae do it all?

Moster+ 2010

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Can Supernovae do it all?

Moster+ 2010

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SLIDE 14

Can Supernovae do it all?

Moster+ 2010

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Can Supernovae do it all? Answer: No!

Halo Mass (1012Msun) Stellar Mass (1011Msun) Keller+ 2016

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Mass loading has universal scaling

  • Mass-loading begins to fall

from ~10 when disc is ~1010Msun, halo is ~2x1011Msun to << 1 in halos above ~1012Msun

  • SDSS observations fjnd

powerful AGN kick in here!

  • Dubois+ 2015 simulations

found AGN regulation began at 280 km/s bulge vesc at high z

Mass Loading Disc Mass Keller+ 2016

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How Gas Moves Through the CGM

  • Do outfmows escape

the halo?

– Wind vs. Fountain

  • Are they driven by

energy, momentum, or something else?

  • How does accreted

material interact with

  • utfmowing material?
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SLIDE 18

What Governs CGM Flow?

  • Physics at work

– Energy/Momentum

injected by FB

– Gravity/Accretion Shock – Hydrodynamic Drag – Radiative Cooling – Buoyancy

  • Buoyancy can add OR

remove radial momentum!

  • Critical Timescales

– Cooling tcool – Gravitational Freefall tf – Brunt-Väisälä tbuouy Feedback Gravity Drag Cooling

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What Governs CGM Flow?

  • Physics at work

– Energy/Momentum

injected by FB

– Gravity/Accretion Shock – Hydrodynamic Drag – Radiative Cooling – Buoyancy

  • Buoyancy can add OR

remove radial momentum!

  • Critical Timescales

– Cooling tcool – Gravitational Freefall tf – Brunt-Väisälä tbuouy

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Buoyancy is all about Entropy! K=kBT n

−2/3

Δ S=Δ ln(K) ∂ S ∂r >0

“Entropy” Entropy

Schwarzchild Criterion Brünt-Väisälä Frequency

ω=√ 3 5 ∇ ϕ∇ S

Keller+ 2018b, in prep

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Buoyancy determines fmow direction

Keller+ 2018b, in prep

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Entropy-Driven Fountains

Keller+ 2018b, in prep

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EoM for Entropy-Driven Fountains Buoyancy Gravity Drag

Keller+ 2018b, in prep

¨ r=∇ ϕ

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Can We Derive the Entropy of a SB? nSB=9.6∘10

−3cm −3 L38 6/35n0 19/35t7 −22/35 Superbubble Density Superbubble Temperature

T SB= 10μm p 33k BmSB Lt

Superbubble Radius

RSB=267 pc L38

1/5n0 −1/5t7 3/5

Weaver+ 1977, Mac Low & McCray 1988

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SLIDE 25

Superbubble Entropy K SB=5.84keV cm

2(

h 267 pc )

26/36

L38

2/63n0 −14/63 Entropy at breakout (R~h) Halo Entropy

K vir=30.06keV cm

2(

M vir 10

12 M sun) 2/3

Keller+ 2018b, in prep

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Integrating the Buoyant EoM

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Buoyant Outfmows Recycle Slowly! Entropy-Driven Energy-Driven

Keller+ 2018b, in prep

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SLIDE 28

Buoyancy determines recycling time

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SLIDE 29

A “Reproducibility Crisis” In Numerical Astrophysics?

Monya Baker, Nature News, 2016

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How Sensitive Are Galaxy Properties to Small Perturbations?

  • N-Body Chaos
  • Infjnitesimal Initial Condition Perturbations
  • Random Number Generator seeds
  • Poisson Noise
  • Floating Point Roundof
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SLIDE 31

Chaos Rules Everything Around Me

Laskar & Gastineau 2009

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Chaos is Important in Protoplanetary Discs: Why Not Galactic Discs?

Hofgmann+ 2017

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Chaos is Universal!

Isolated Dwarf Galaxy Cosmological MW Zoom

  • All codes
  • All subgrid feedback models
  • All initial conditions
  • See also Genel+ 2018

Keller+ 2018a, submitted Difgerence in Stellar Mass Between Runs

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SLIDE 34

Keller+ 2018a, submitted

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SLIDE 35

Keller+ 2018a, submitted

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Feedback & Gas Exhaustion Constrain Stochasticity

No Feedback: Gas Exhaustion Feedback: Self-Regulation

Variance in Stellar Mass Time

Keller+ 2018a, submitted

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Starbursts & Mergers Pump Chaos

Merger Isolated/

Keller+ 2018a, submitted

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SLIDE 38

T emporal ~ Numerical Stochasticity

Stellar Surface Density

Keller+ 2018a, submitted

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T emporal ~ Numerical Stochasticity Run-to-Run Variation Step-to-Step Variation

Keller+ 2018a, submitted

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What does “simulation” mean?

Confjguration Space

Final State Initial Conditions S i m u l a t i

  • n

Model 1 Model 2

Keller+ 2018a, submitted

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SLIDE 41

What does “simulation” mean?

Confjguration Space

Final State a Initial Conditions Final State b S i m u l a t i

  • n

Model 1 Model 2

Keller+ 2018a, submitted

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SLIDE 42

What does “simulation” mean?

Keller+ 2018a, submitted

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SLIDE 43

What does “simulation” mean?

Keller+ 2018a, submitted

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Conclusions

  • Highly mass-loaded outfmows, especially at high-z, are

essential to forming realistic L* galaxies

– These outfmows cannot be driven by SN alone in halos more

massive than 1012 Msun

  • Entropy-driven winds, driven by buoyancy, behave quite

diferently than ballistic outfmows

– Gentle acceleration, low velocities – Long recycling times – Halo entropy exceeds superbubble entropy near 1012 Msun,

halting outfmows

  • Galaxy evolution involves chaotic physics: small-scale

stochasticity can pump large-scale changes

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