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

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1 10

Permissible Models

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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

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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

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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⊙

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The Most Massive Stars that Ever Lived!?

Haemmerle, Woods, et al. (2018a)

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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

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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

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Tyrone E. Woods TITANS OF THE EARLY UNIVERSE June 29th , 2018 18 / 20

Supermassive Stars

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0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2

CO

RE

HE

LIU

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DR

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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)

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