Two Modes of Accretion onto ∼L∗ Galaxies
Jonathan Stern
(Northwestern University)
Collaborators:D. Fielding (CCA), C.-A. Faucher-Giguere (Northwestern), E. Quataert (UC Berkeley), Z. Hafen(Northwestern), L. Byrne (Northwestern), D. Angles-Alcazar (CCA), and the FIRE team
Papers:Stern et al. 2018, 2019a,b: arXiv:1909.07402; MNRAS 488 2549; ApJ 865 91
J. Stern (Northwestern) Berlin 2019 1 / 15
How the Global CGM Structure affects Star Formation
Behroozi et al. (2019)
tcool � tff
free-fall, cold flows
tcool � tff
∼HSE, cooling flows
tcool ∼ tff
?
refs:
Rees&Ostriker ’77; White&Rees ’78; Birnboim&Dekel ’03; Dusan+2005, 2009; Nelson+2013; Fielding+2017
J. Stern (Northwestern) Berlin 2019 2 / 15
Outline
The transition between free-fall and cooling flows in:
1 Steady-state solutions for halo gas
2 Idealized hydro simulations
3 The FIRE cosmological simulations
4 Observations
complexity
J. Stern (Northwestern) Berlin 2019 3 / 15
Steady-state Solutions for the Volume-Filling Phase
Equations
M = −4πr2ρv
1
2
dv2
dr= −1
ρ
dP
dr− g +
j2
r3
d ln(P/ργ)
dr=
1
−v · tcool
Solution for logMh = 12.2, z = 0
104
105
106
107
tem
pera
ture
[K]
fCGM = 1, 0.3Z ¯
rotationalsupport
Tvir
coolingflow
0.1
1
10
Mac
h
0.1
1
10
∼t c
ool/t f
f
0.05 0.1 0.2 0.5 1
r/Rvir
0.1
1
10
100en
trop
y[k
eV c
m−
2]
Stern+19a,b
J. Stern (Northwestern) Berlin 2019 4 / 15
Steady-state Solutions for the Volume-Filling Phase
Equations
M = −4πr2ρv
1
2
dv2
dr= −1
ρ
dP
dr− g +
j2
r3
d ln(P/ργ)
dr=
1
−v · tcool
Solution for logMh = 12.1, z = 0.3
104
105
106
107
tem
pera
ture
[K]
fCGM = 1, 0.3Z ¯
rotationalsupport
Tvir
coolingflow
0.1
1
10
Mac
h
0.1
1
10
∼t c
ool/t f
f
0.05 0.1 0.2 0.5 1
r/Rvir
0.1
1
10
100en
trop
y[k
eV c
m−
2]
Stern+19a,b
J. Stern (Northwestern) Berlin 2019 4 / 15
Steady-state Solutions for the Volume-Filling Phase
Equations
M = −4πr2ρv
1
2
dv2
dr= −1
ρ
dP
dr− g +
j2
r3
d ln(P/ργ)
dr=
1
−v · tcool
Solution for logMh = 12.0, z = 0.6
104
105
106
107
tem
pera
ture
[K]
fCGM = 1, 0.3Z ¯
rotationalsupport
Tvir
coolingflow
0.1
1
10
Mac
h
0.1
1
10
∼t c
ool/t f
f
0.05 0.1 0.2 0.5 1
r/Rvir
0.1
1
10
100en
trop
y[k
eV c
m−
2]
Stern+19a,b
J. Stern (Northwestern) Berlin 2019 4 / 15
Steady-state Solutions for the Volume-Filling Phase
Equations
M = −4πr2ρv
1
2
dv2
dr= −1
ρ
dP
dr− g +
j2
r3
d ln(P/ργ)
dr=
1
−v · tcool
Solution for logMh = 11.9, z = 1
104
105
106
107
tem
pera
ture
[K]
fCGM = 1, 0.3Z ¯
rotationalsupport
Tvir
coolingflow
0.1
1
10
Mac
h
0.1
1
10
∼t c
ool/t f
f
0.05 0.1 0.2 0.5 1
r/Rvir
0.1
1
10
100en
trop
y[k
eV c
m−
2]
Stern+19a,b
J. Stern (Northwestern) Berlin 2019 4 / 15
Steady-state Solutions for the Volume-Filling Phase
Equations
M = −4πr2ρv
1
2
dv2
dr= −1
ρ
dP
dr− g +
j2
r3
d ln(P/ργ)
dr=
1
−v · tcool
Solution for logMh = 11.6, z = 1.5
104
105
106
107
tem
pera
ture
[K]
fCGM = 1, 0.3Z ¯
rotationalsupport
Tvir
freefall
coolingflow
0.1
1
10
Mac
h
0.1
1
10
∼t c
ool/t f
f
0.05 0.1 0.2 0.5 1
r/Rvir
0.1
1
10
100en
trop
y[k
eV c
m−
2]
Stern+19a,b
J. Stern (Northwestern) Berlin 2019 4 / 15
Steady-state Solutions for the Volume-Filling Phase
Equations
M = −4πr2ρv
1
2
dv2
dr= −1
ρ
dP
dr− g +
j2
r3
d ln(P/ργ)
dr=
1
−v · tcool
Solution for logMh = 11.4, z = 2.2
104
105
106
107
tem
pera
ture
[K]
fCGM = 1, 0.3Z ¯
rotationalsupport
Tvir
freefall
coolingflow
0.1
1
10
Mac
h
0.1
1
10
∼t c
ool/t f
f
0.05 0.1 0.2 0.5 1
r/Rvir
0.1
1
10
100en
trop
y[k
eV c
m−
2]
Stern+19a,b
J. Stern (Northwestern) Berlin 2019 4 / 15
Steady-state Solutions for the Volume-Filling Phase
Equations
M = −4πr2ρv
1
2
dv2
dr= −1
ρ
dP
dr− g +
j2
r3
d ln(P/ργ)
dr=
1
−v · tcool
Solution for logMh = 11.2, z = 3
104
105
106
107
tem
pera
ture
[K]
fCGM = 1, 0.3Z ¯
rotationalsupport
Tvir
freefall
coolingflow
0.1
1
10
Mac
h
0.1
1
10
∼t c
ool/t f
f
0.05 0.1 0.2 0.5 1
r/Rvir
0.1
1
10
100en
trop
y[k
eV c
m−
2]
Stern+19a,b
J. Stern (Northwestern) Berlin 2019 4 / 15
Steady-state Solutions for the Volume-Filling Phase
Equations
M = −4πr2ρv
1
2
dv2
dr= −1
ρ
dP
dr− g +
j2
r3
d ln(P/ργ)
dr=
1
−v · tcool
Solution for logMh = 11.0, z = 4
104
105
106
107
tem
pera
ture
[K]
fCGM = 1, 0.3Z ¯
rotationalsupport
Tvir
freefall
coolingflow
0.1
1
10
Mac
h
0.1
1
10
∼t c
ool/t f
f
0.05 0.1 0.2 0.5 1
r/Rvir
0.1
1
10
100en
trop
y[k
eV c
m−
2]
Stern+19a,b
J. Stern (Northwestern) Berlin 2019 4 / 15
Steady-state Solutions for the Volume-Filling Phase
Equations
M = −4πr2ρv
1
2
dv2
dr= −1
ρ
dP
dr− g +
j2
r3
d ln(P/ργ)
dr=
1
−v · tcool
Solution for logMh = 10.7, z = 5
104
105
106
107
tem
pera
ture
[K]
fCGM = 1, 0.3Z ¯
rotationalsupport
Tvir
freefall
0.1
1
10
Mac
h
0.1
1
10
∼t c
ool/t f
f
0.05 0.1 0.2 0.5 1
r/Rvir
0.1
1
10
100en
trop
y[k
eV c
m−
2]
Stern+19a,b
J. Stern (Northwestern) Berlin 2019 4 / 15
Steady-state Solutions for the Volume-Filling Phase
Equations
M = −4πr2ρv
1
2
dv2
dr= −1
ρ
dP
dr− g +
j2
r3
d ln(P/ργ)
dr=
1
−v · tcool
Solution for logMh = 10.4, z = 7
104
105
106
107
tem
pera
ture
[K]
fCGM = 1, 0.3Z ¯
rotationalsupport
Tvir
freefall
0.1
1
10
Mac
h
0.1
1
10
∼t c
ool/t f
f
0.05 0.1 0.2 0.5 1
r/Rvir
0.1
1
10
100en
trop
y[k
eV c
m−
2]
Stern+19a,b
J. Stern (Northwestern) Berlin 2019 4 / 15
Three Types of Solutions for the Global CGM Structure
tcool > tfftcool < tff at small rtcool > tff at large r
tcool < tff
Rvir
cooling flow
galaxy
Rvir
free fall Rsonic
cooling flow
galaxy
Rvir
free fall
galaxy
Stern+19b
accretion mode onto galaxy determined by tcool/tff at galaxy outskirts
J. Stern (Northwestern) Berlin 2019 5 / 15
The Global CGM Structure in 3D Idealized Simulations
Conclusions fromsteady-state solutionssupported by idealizedsimulations
Thermal instabilitiesdevelop only in free-fallinggas where tcool < tff(see Balbus & Soker ’89)
Stern+19b, sims by D. Fielding
t cool
decre
ase
s−→
tcool = tff at 10 kpc
J. Stern (Northwestern) Berlin 2019 6 / 15
Identification of Transition in FIRE ‘Zoom’ Simulations
0 1 2 3 4 5
redshift
0.1
1
10
100
1000
104tim
esca
les
at≈
0.05R
vir
[Myr]
x
m12i
cooling time
free fall time
0.01× tHubble
tcool = tff
Stern et al. (in prep.)
J. Stern (Northwestern) Berlin 2019 7 / 15
A Major Change in the Global Structure of the CGM
logMh = 12; z = 0.5; tcooltff
≈ 3 logMh = 11.9; z = 1; tcooltff
≈ 13
Stern et al. (in prep.)
free-fall
cooling flow
J. Stern (Northwestern) Berlin 2019 8 / 15
Identification of Transition in FIRE ‘Zoom’ Simulations
0 1 2 3 4 5 7
redshift
11
12
13
log
halo
mas
s [M
¯]
m12im12bA4A1
12510time [Gyr]
0 1 2 3 4 50.1
1
10
100
1000
104 x
m12i
cooling time
free fall time
0.01× tHubble
0 1 2 3 4 5
x
m12b
1 2 3 4 5 7
redshift
0.1
1
10
100
1000
104 x
A41 2 3 4 5 7
redshift
x
A1
tim
esca
les
at≈
0.05R
vir
[Myr]
Stern et al. (in prep.)
J. Stern (Northwestern) Berlin 2019 9 / 15
SF-driven outflows cease when tcool > tff at ≈ 0.05Rvir
0 1 2 3 4 5
redshift
1.0
0.5
0.0
0.5
1.0
1.5v r/v
circ
x
m12i
0.1 Rvir
tcool < tfftcool > tff
Stern et al. (in prep.)
J. Stern (Northwestern) Berlin 2019 10 / 15
SF-driven outflows cease when tcool > tff at ≈ 0.05Rvir
0 1 2 3 4 5 7
redshift
11
12
13
log
halo
mas
s [M
¯]
m12im12bA4A1
12510time [Gyr]
0 1 2 3 4 51.0
0.5
0.0
0.5
1.0
1.5x
m12i0 1 2 3 4 5
x
m12b
1 2 3 4 5 7
redshift
1.0
0.5
0.0
0.5
1.0
1.5x
A41 2 3 4 5 7
redshift
x
A1
v r/v
circ
Stern et al. (in prep.)
J. Stern (Northwestern) Berlin 2019 11 / 15
Accretion mode versus the Star Formation Rate
0 1 2 30.1
1
10SFR/S
FR
m12i0 1 2 3
m12b
1 2 3 4 5 6 7 8redshift
0.1
1
10
SFR/S
FR
A41 2 3 4 5 6 7 8
redshift
A1
Stern et al. (in prep.), SFRs see Faucher-Giguere (2018)
Transition in accretion mode coincides with transition to steady SFR
J. Stern (Northwestern) Berlin 2019 12 / 15
Accretion mode versus the Star Formation Rate
0 1 2 30.1
1
10SFR/S
FR
m12i
x
0 1 2 3m12b
0.01
0.1
1
10
100
t coo
l/t f
fat≈
0.05R
vir
x
1 2 3 4 5 6 7 8redshift
0.1
1
10
SFR/S
FR
A4
x
1 2 3 4 5 6 7 8redshift
A10.01
0.1
1
10
100
t cool/t
ffat≈
0.05R
vir
x
Stern et al. (in prep.), SFRs see Faucher-Giguere (2018)
Transition in accretion mode coincides with transition to steady SFR
J. Stern (Northwestern) Berlin 2019 12 / 15
Accretion mode versus Black Hole Growth
1 2 3 4 5 610−4
10−3
0.01
0.1
1
BH
acc
retio
n ra
te A8
1 2 3 4 5 6
A2
1 2 3 4 5 6redshift
10−4
10−3
0.01
0.1
1
BH
acc
retio
n ra
te A1
1 2 3 4 5 6redshift
A4
Byrne et al. (in prep.); MBH from Angles-Alcazar+17
Transition in accretion mode coincides with significant BH growth
J. Stern (Northwestern) Berlin 2019 13 / 15
Accretion mode versus Black Hole Growth
1 2 3 4 5 610−4
10−3
0.01
0.1
1
BH
acc
retio
n ra
te A8
1 2 3 4 5 6
A2
1 2 3 4 5 6redshift
10−4
10−3
0.01
0.1
1
BH
acc
retio
n ra
te A1
1 2 3 4 5 6redshift
A4
x
0.01
0.1
1
10
100
t coo
l/t f
fat≈
0.05R
vir
x
x
0.01
0.1
1
10
100
t coo
l/t f
fat≈
0.05R
vir
x
Byrne et al. (in prep.); MBH from Angles-Alcazar+17
Transition in accretion mode coincides with significant BH growth
J. Stern (Northwestern) Berlin 2019 13 / 15
Kinematics of free-fall in UV absorbers
Stern+18, obs’ from COS-Halos (SF galaxies)
predicted velocity shear in free-
falling gas for different OVI densities
OVI densities suggested by line ratios
OVI widths consistent with free-falling gas
J. Stern (Northwestern) Berlin 2019 14 / 15
Summary: Two Accretion Modes onto ∼L∗ Galaxies
1 The nature of accretion determined by conditions at galaxy outskirts
2 Transition in accretion onto galaxies in FIRE coincides with
cessation of SF-driven outflowstransition from bursty to steady star formationonset of BH growth
3 OVI widths consistent with free-falling outer CGM around SF galaxies
J. Stern (Northwestern) Berlin 2019 15 / 15
