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TITANS OF THE EARLY UNIVERSE The origin of the first supermassive black holes Tyrone E. Woods Monash Centre for Astrophysics July 18, 2018 With Alex Heger, Ralf Klessen, Lionel Haemmerle, and Daniel J. Whalen Tyrone E. Woods July 18, 2018 1

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TITANS OF THE EARLY UNIVERSE

The origin of the first supermassive black holes

Tyrone E. Woods Monash Centre for Astrophysics July 18, 2018 With Alex Heger, Ralf Klessen, Lionel Haemmerle, and Daniel J. Whalen

Tyrone E. Woods

TITANS OF THE EARLY UNIVERSE

July 18, 2018 1 / 31

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TITANS OF THE EARLY UNIVERSE

The origin of the first supermassive black holes

Tyrone E. Woods Institute of Gravitational Wave Astronomy University of Birmingham July 18, 2018 With Alex Heger, Ralf Klessen, Lionel Haemmerle, and Daniel J. Whalen

Tyrone E. Woods

TITANS OF THE EARLY UNIVERSE

July 18, 2018 2 / 31

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No hot and luminous progenitor for most Type Ia supernovae

Woods, Ghavamian, Badenes, and Gilfanov, Nature Astronomy, 2017 See also, e.g., Woods & Gilfanov 2013, 2014, 2016 Johansson, Woods et al., 2014, 2016

1 2 3 4

0.51M⊙ 0.6M⊙ 0.8M⊙ 1.0M⊙ 1.2M⊙ 1.4M⊙

n = 1 c m

  • 3

, d = 3 p c log10 Bolometric Luminosity (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

July 18, 2018 3 / 31

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The Origin of High-redshift Quasars

Tyrone E. Woods

TITANS OF THE EARLY UNIVERSE

July 18, 2018 4 / 31

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The Origin of High-redshift Quasars

Truly massive (109–1010M⊙) quasars have been

  • bserved at redshift ∼7 (e.g., Mortlock+ 2011,

Wu+ 2015). This is hard to explain: tgrowth ∼ 0.1log10 MBH Mseed

  • Gyr

Especially given pop III black holes “born starving” (Alvarez, Wise, & Abel 2009)

Tyrone E. Woods

TITANS OF THE EARLY UNIVERSE

July 18, 2018 5 / 31

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The Origin of High-redshift Quasars

Tyrone E. Woods

TITANS OF THE EARLY UNIVERSE

July 18, 2018 6 / 31

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The Origin of High-redshift Quasars

See review by Mar Mezcua, 2017

Tyrone E. Woods

TITANS OF THE EARLY UNIVERSE

July 18, 2018 7 / 31

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Supermassive Stars – a little history

How massive is supermassive? 104–106M⊙ Initially hypothesized candidate for quasars Assumed to be formed “all at once” (monolithically) Strongly radiation-dominated (β =

Pgas Ptot << 1):

P ∝ ρ

4 3 → polytrope, with index n = 3

Local adiabatic index Γ = 1 + 1

n ≈ 4 3 + β 6

Tyrone E. Woods

TITANS OF THE EARLY UNIVERSE

July 18, 2018 8 / 31

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Supermassive Stars – a little history

Objects with Γ ≈ 4/3 are “trembling on the verge of instability” (Fowler 1964) Very small perturbation can trigger collapse! Chandrasekhar (1964) and others showed that there is a general relativistic correction to the critical pressure support needed: Γ ≈ 4/3 + 1.122GM

Rc2

Criterion for instability: β

6 < 1.122GM Rc2

β ∝ M − 1

2 for β << 1 → ∼ 105–106M⊙ stars will

quickly collapse!

Tyrone E. Woods

TITANS OF THE EARLY UNIVERSE

July 18, 2018 9 / 31

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KEPLER Stellar Evolution Code

implicit Lagrangian hydrodynamics and stellar evolution (Weaver, Zimmerman, and Woosley 1978) solve conservation equations for mass, energy, and momentum in spherical symmetry equation of state allowing for general mixture of radiation, ions, and electrons of arbitrary degeneracy and relativity, as well as pair production include post-Newtonian correction to the acceleration due to gravity (e.g., Fuller+ 1986)

Tyrone E. Woods

TITANS OF THE EARLY UNIVERSE

July 18, 2018 10 / 31

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Monolithic Supermassive Stars

Tyrone E. Woods

TITANS OF THE EARLY UNIVERSE

July 18, 2018 11 / 31

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Monolithic Supermassive Stars

Tyrone E. Woods

TITANS OF THE EARLY UNIVERSE

July 18, 2018 12 / 31

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Supermassive Stars

0.01 0.1 1 10 2000 3000 4000 5000 6000 7000 8000 9000 10000 Specific Volume [cm3g-1] Time [years] 155000 M⊙ 156000 M⊙

Tyrone E. Woods

TITANS OF THE EARLY UNIVERSE

July 18, 2018 13 / 31

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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

CORE HELIUM BURNING CORE HYDROGEN BURNING DIRECT COLLAPSE

Lifetime [Years] Mass [105MO

. ]

Tyrone E. Woods

TITANS OF THE EARLY UNIVERSE

July 18, 2018 14 / 31

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How do you actually make a supermassive star?

Option 1: Regan+, Nature Astro, 2017

Tyrone E. Woods

TITANS OF THE EARLY UNIVERSE

July 18, 2018 15 / 31

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How do you actually make a supermassive star?

Option 2: high baryonic streaming velocities (Tanaka & Li 2014; Schauer et al., 2017; Hirano et al., 2017). Essentially an atomically-cooled halo with an assist? Option 3: really massive infall rates possible in high-z galaxy mergers? (Maier et al 2015) Option 4: Coalesence of a dense stellar cluster? (problems, see Latif et al., 2016)

Tyrone E. Woods

TITANS OF THE EARLY UNIVERSE

July 18, 2018 16 / 31

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Initial Conditions

Begin with a 10M⊙, n = 3 polytrope with a central density of 10−3gcm−3 → a somewhat “puffy” protostar. Primordial composition, including deuterium and lithium. Consider accretion rates in the range 0.01 – 10 M⊙/yr, typical of atomically-cooled haloes

Tyrone E. Woods

TITANS OF THE EARLY UNIVERSE

July 18, 2018 17 / 31

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Accreting Supermassive Stars Don’t Know how to Relax!

Haemmerle, Woods, et al. (2017)

Tyrone E. Woods

TITANS OF THE EARLY UNIVERSE

July 18, 2018 18 / 31

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The Onset of Nuclear-burning

106 107 108 109 10-3 10-2 10-1 100 101 102 103 104 105 106 Temperature [K] Density [g/cm-3] 10-10 10-9 10-8 10-7 100 101 102 103 104 105 CNO Mass Fraction Time [yr]

Blue – 1M⊙/yr Red – 10 M⊙/yr

Tyrone E. Woods

TITANS OF THE EARLY UNIVERSE

July 18, 2018 19 / 31

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A Representative Case: 1M⊙/yr

Tyrone E. Woods

TITANS OF THE EARLY UNIVERSE

July 18, 2018 20 / 31

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Reminder: criterion for onset of instability

Recall the Chandrasekhar general relativistic instability for supermassive stars:

P ∝ ρ

4 3 → polytrope, with index n = 3

Local adiabatic index Γ = 1 + 1

n ≈ 4 3 + β 6

Chandrasekhar (1964) and others showed that there is a general relativistic correction to the critical pressure support needed: Γ ≈ 4/3 + 1.122GM

Rc2

Polytropic criterion for instability: β

6 < 1.122GM Rc2

Tyrone E. Woods

TITANS OF THE EARLY UNIVERSE

July 18, 2018 21 / 31

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When does collapse set in?

0.001 0.002 0.003 0.004 0.005 0.006 0.007 0.008 0.009 0.01 102 103 104 105 106 β/6, 1.12(2GM)/Rc2 Mass coordinate [M⊙] β/6, 105M⊙ 1.12(2GM)/Rc2, 105M⊙ β/6, 3.2 x 105M⊙ 1.12(2GM)/Rc2, 3.2 x 105M⊙

Tyrone E. Woods

TITANS OF THE EARLY UNIVERSE

July 18, 2018 22 / 31

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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 stars

final mass (105 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

MSMS,final ≈

  • 0.83 log10
  • ˙

M M⊙ yr−1

  • + 2.48
  • × 105 M⊙

Tyrone E. Woods

TITANS OF THE EARLY UNIVERSE

July 18, 2018 23 / 31

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The Most Massive Stars that Ever Lived!?

Tyrone E. Woods

TITANS OF THE EARLY UNIVERSE

July 18, 2018 24 / 31

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Accreting Supermassive Stars with “realistic” accretion rates

Tyrone E. Woods

TITANS OF THE EARLY UNIVERSE

July 18, 2018 25 / 31

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Accreting Supermassive Stars with “realistic” accretion rates

Tyrone E. Woods

TITANS OF THE EARLY UNIVERSE

July 18, 2018 26 / 31

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Rotating Supermassive Stars

ΩΓ-limit: known problem from “normal” Pop I massive star evolution

v2

crit,1

Req = GM R2

eq → vcrit,1 =

  • GM

Req

v2

crit,2 = 2πGρ(1 − ΓEdd)R2 eq

Tyrone E. Woods

TITANS OF THE EARLY UNIVERSE

July 18, 2018 27 / 31

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Rotating Supermassive Stars

Haemmerle et al., 2017, submitted: Supermassive stars have to be slow rotators (vsurf < 10−20%vcrit,1). Supermassive star formation by accretion requires mechanisms efficient enough to remove most (≈99%) of the angular momentum from the accretion disc. Need to get rid of a lot of angular momentum somehow! Spiral arms in the disk? Magnetic braking?

Tyrone E. Woods

TITANS OF THE EARLY UNIVERSE

July 18, 2018 28 / 31

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Tyrone E. Woods

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July 18, 2018 29 / 31

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Conclusions

Supermassive protostars accreting 0.1M⊙/yr collapse due to the GR while H-burning Final fate of (non-rotating) supermassive stars depends in a reliable way on accretion rate (variable rates qualitatively similar) Rotation rates of supermassive stars strongly constrained Even for non-rotating case, n=3 polytrope poorly predicts moment of collapse... including when applied only to the core. www.tewoods-astro.com

Tyrone E. Woods

TITANS OF THE EARLY UNIVERSE

July 18, 2018 30 / 31

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KEPLER Stellar Evolution Code

dv d t = 4πr 2 ∂ P ∂ mr − Grelmr r 2 + 4π r ∂ Q ∂ mr d u d t = −4πP ∂ ∂ mr (v r 2) + 4πQ ∂ ∂ mr v r

  • − ∂ L

∂ mr + ε Grel = G

  • 1 + P

ρc2 + 2GM rc2 + 4πP r 3 mr c2

  • Tyrone E. Woods

TITANS OF THE EARLY UNIVERSE

July 18, 2018 31 / 31