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TITANS OF THE EARLY UNIVERSE
The origin of the most massive high-redshift quasars
Tyrone E. WoodsMonash Centre for Astrophysics
June 29th, 2018
With Alex Heger, Ralf Klessen, Lionel Haemmerle,and Daniel J. Whalen
Tyrone E. Woods TITANS OF THE EARLY UNIVERSE June 29th , 2018 1 / 20
Update: No hot and luminousprogenitor for most Type Ia supernovae
Woods, Ghavamian,Badenes, andGilfanov, NatureAstronomy, 2017
See also, e.g., Woods& Gilfanov 2013,2014, 2016 Johansson,Woods et al., 2014,2016
1
2
3
40.51M
⊙
0.6M⊙
0.8M⊙
1.0M⊙
1.2M⊙
1.4M⊙
n = 1cm -3, d = 3pc
log 1
0 B
olom
etric
Lum
inos
ity (
erg/
s)
Effective Temperature (105K)
Excluded Progenitors of Tycho’s Supernova
34
34.5
35
35.5
36
36.5
37
37.5
38
38.5
1 10
Permissible Models
Tyrone E. Woods TITANS OF THE EARLY UNIVERSE June 29th , 2018 2 / 20
The Origin of High-redshift Quasars
Tyrone E. Woods TITANS OF THE EARLY UNIVERSE June 29th , 2018 3 / 20
The Origin of High-redshift Quasars
Massive (109–1010M⊙
) quasars have been observed atz ∼7 (e.g., Mortlock+ 2011, Wu+ 2015).
This is hard to explain:
tgrowth ∼ 0.45 log
�
MBH
Mseed
�
Gyr
Especially given pop III black holes “born starving”(Alvarez, Wise, & Abel 2009); unable to reach suchhigh masses by z∼7 via mergers
Tyrone E. Woods TITANS OF THE EARLY UNIVERSE June 29th , 2018 4 / 20
The Origin of High-redshift Quasars
Tyrone E. Woods TITANS OF THE EARLY UNIVERSE June 29th , 2018 5 / 20
Supermassive Stars – a little history
How massive is supermassive? 104–106M⊙
Originally assumed to be formed “all at once” (e.g.,monolithically, well-approximated by a polytrope)
Strongly radiation-dominated (β=Pgas
Ptot<< 1):
P∝ ρ43 → polytrope, with index n = 3
Local adiabatic index Γ = 1+ 1
n≈
4
3+β6
Tyrone E. Woods TITANS OF THE EARLY UNIVERSE June 29th , 2018 6 / 20
Supermassive Stars – a little history
Γ ≈ 4/3→ “trembling on the verge of instability”(Fowler 1964)
Very small perturbation can trigger collapse!
Chandrasekhar (1964) and others showed that thereis a general relativistic correction to the critical
pressure support needed: Γ ≈ 4/3+ 1.122GM
Rc2
Leads to an upper limit to mass, above which starcollapses
Tyrone E. Woods TITANS OF THE EARLY UNIVERSE June 29th , 2018 7 / 20
So how do you actually make a directcollapse black hole seed?
Regan+, Nature Astro, 2017
Tyrone E. Woods TITANS OF THE EARLY UNIVERSE June 29th , 2018 8 / 20
Accreting Supermassive Stars Don’tKnow how to Relax!
Haemmerle, Woods, et al. (2018a)Tyrone E. Woods TITANS OF THE EARLY UNIVERSE June 29th , 2018 9 / 20
KEPLER Stellar Evolution Code
implicit Lagrangian hydrodynamics and stellarevolution (Weaver, Zimmerman, and Woosley 1978)
solve conservation equations for mass, energy, andmomentum in spherical symmetry
equation of state allowing for general mixture ofradiation, ions, and electrons of arbitrarydegeneracy and relativity, as well as pair production
include post-Newtonian correction to theacceleration due to gravity (e.g., Fuller+ 1986)
Tyrone E. Woods TITANS OF THE EARLY UNIVERSE June 29th , 2018 10 / 20
The Onset of Nuclear-burning
106
107
108
109
10-310-210-1100101102103104105106
Tem
pera
ture
[K]
Den
sity
[g/c
m-3
]
10-10
10-9
10-8
10-7
100 101 102 103 104 105
CN
O M
ass
Fra
ctio
n
Time [yr]
Blue – 1M⊙/yr Red – 10 M
⊙/yr
Tyrone E. Woods TITANS OF THE EARLY UNIVERSE June 29th , 2018 11 / 20
The Most Massive Stars that Ever Lived!?Collapse after H-exhaustion
GR collapse during H-burning
Hydrostatic limit for H-burning monolithic stars
Hydrostatic limit for He-burning monolithic starsfinal
mas
s (1
05 M⊙
)
accretion rate (M⊙ yr-1)
0.3
0.4
0.5 0.6
0.8
1
1.5
2
3
0.01 0.1 1 10
Woods, Heger, et al. (2017)
MSMS,final ≈
h
0.83 log10
�
MM⊙
yr−1
�
+ 2.48i
× 105 M⊙
Tyrone E. Woods TITANS OF THE EARLY UNIVERSE June 29th , 2018 12 / 20
The Most Massive Stars that Ever Lived!?
Haemmerle, Woods, et al. (2018a)
Tyrone E. Woods TITANS OF THE EARLY UNIVERSE June 29th , 2018 13 / 20
Rotating Supermassive Stars
Haemmerle, Woods et al., 2018b: Supermassivestars have to be slow rotators (vsurf < 10−20%vcrit,1).
Supermassive star formation by accretion requiresmechanisms efficient enough to remove most(≈99%) of the angular momentum from theaccretion disc.
Need to get rid of a lot of angular momentumsomehow! Spiral arms in the disk? Magneticbraking?
Tyrone E. Woods TITANS OF THE EARLY UNIVERSE June 29th , 2018 14 / 20
Accreting Supermassive Stars with“realistic” accretion rates
Tyrone E. Woods TITANS OF THE EARLY UNIVERSE June 29th , 2018 15 / 20
Tyrone E. Woods TITANS OF THE EARLY UNIVERSE June 29th , 2018 16 / 20
Conclusions
Supermassive protostars a natural consequence ofatomically-cooled halos, though need to account forfragmentation!
Initial masses of DCBHs depends in a reliable wayon accretion rate (variable rates qualitativelysimilar). Can’t form as rapid rotators (need to getrid of that ang. mom. somehow...)
JWST, Euclid, and the search for IMBHs will soongive us a real idea of the seeds of the first quasars!
www.tewoods-astro.com
Tyrone E. Woods TITANS OF THE EARLY UNIVERSE June 29th , 2018 17 / 20
Tyrone E. Woods TITANS OF THE EARLY UNIVERSE June 29th , 2018 18 / 20
Supermassive Stars
103
104
105
106
107
0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2
CO
RE
HE
LIU
M
BU
RN
ING
CO
RE
HY
DR
OG
EN
BU
RN
ING
DIR
EC
T C
OL
LA
PS
E
Life
time
[Yea
rs]
Mass [105MO. ]
Woods, Heger, et al., (2018, in prep.)Tyrone E. Woods TITANS OF THE EARLY UNIVERSE June 29th , 2018 19 / 20
Supermassive Stars
Probably only way to make such objects is throughdisruption of a dense cluster→ can only makeobjects up to a few thousand solar masses (see e.g,.Latif & Ferrara 2016 and references therein)
No apparent route to nuclear explosions or “trulydirect” collapse
Would suffer huge pulsational mass losses anyway(see e.g., Hosokawa et al., 2012)
Tyrone E. Woods TITANS OF THE EARLY UNIVERSE June 29th , 2018 20 / 20