Dynamical formation ! of black-hole X -ray binaries Ross Church ! - - PowerPoint PPT Presentation

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Dynamical formation ! of black-hole X -ray binaries Ross Church ! - - PowerPoint PPT Presentation

Dec 13, 2022 229 likes •451 views

Dynamical formation ! of black-hole X -ray binaries Ross Church ! Department of Astronomy and Theoretical Physics ! Lund University ! ! ! With thanks to: ! Melvyn B. Davies (Lund), Seppo Mikkola (Turku) ! Black-hole X -ray binaries in GCs

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Ross Church! Department of Astronomy and Theoretical Physics! Lund University!

! !

With thanks to:! Melvyn B. Davies (Lund), Seppo Mikkola (Turku)!

Dynamical formation !

  • f black-hole X-ray binaries
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Black-hole X-ray binaries in GCs

Miller-Jones et al. (2015)

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Is the tidal capture of black holes enhanced by binaries?

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Tidal capture of BHs by binaries

Two aspects:

  • 1. Black hole - star tidal interactions
  • 2. Three-body (BH + binary) simulations

ARCHAIN SPH

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Setup

5 M black hole Range of pericentre separations Measure: ✏ = E/µ δM? αJ = Jfinal/Jinitial 0.6 M or 0.8 M main-sequence star

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Results

Very strong function of pericentre separation q = 1 R q = 2 R

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Results

1 1.25 1.5 1.75 2 2.125 2.25 2.375 2.5 2.625 2.75 1 2 3 4 q = rmin/R 10−5 10−4 10−3 0.01 0.1 1 −δ (Solar units) M1 = 0.8 M M1 = 0.6 M exp (f1c [log (x) ]) exp (f106 [log (x) ]) Change in specific energy

Lines are fits using functional form of Fabian, Pringle & Rees (1975)

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Tidal capture of BHs by binaries

Two aspects:

  • 1. Black hole - star tidal interactions
  • 2. Three-body (BH + binary) simulations

ARCHAIN SPH

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Simulation setup

3-body scattering experiment (binary + black hole) Binary initially 100 au, thermal eccentricity distribution Impact parameter distribution dN db ∝ b M1 = 0.8 M M2 = 0.6 M M• = 5 M v∞ = 10 km/s

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Outcomes: flyby

−500 −250 250 500 x/R −500 −250 250 500 y/R Star 1 Star 2 BH Flyby −105 −75000 −50000 −25000 (t − t0)/τ 10 30 100 300 1000 3000 xi,j/R x1,2 x1,3 x2,3 Flyby

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Outcomes: exchange

−2000 −1000 1000 2000 x/R −2000 −1000 1000 2000 y/R Star 1 Star 2 BH Clean exchange −80000 −40000 40000 80000 (t − t0)/τ 10 30 100 300 1000 3000 xi,j/R x1,2 x1,3 x2,3 Clean exchange

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Outcomes: collision

−2000 −1000 1000 2000 x/R −2000 −1000 1000 2000 y/R Star 1 Star 2 BH Direct collision −105 −75000 −50000 −25000 (t − t0)/τ 100 200 500 1000 2000 5000 xi,j/R x1,2 x1,3 x2,3 Direct collision

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Outcomes: "dirty" capture

−2000 −1000 1000 2000 x/R −2000 −1000 1000 2000 y/R Star 1 Star 2 BH Type A capture (star survives) 5 × 106 107 1.5 × 107 2 × 107 (t − t0)/τ 1 10 100 1000 10000 xi,j/R x1,2 x1,3 x2,3 Type A capture (star survives)

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Outcomes: "dirty" capture

5 × 106 107 1.5 × 107 2 × 107 (t − t0)/τ 1 10 100 1000 10000 xi,j/R x1,2 x1,3 x2,3 Type A capture (star survives) 1.675 × 107 1.7 × 107 1.725 × 107 1.75 × 107 1.775 × 107 (t − t0)/τ 1 10 100 1000 10000 xi,j/R x1,2 x1,3 x2,3 Type A capture (star survives)

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Outcomes: "messy" capture

−2000 −1000 1000 2000 x/R −2000 −1000 1000 2000 y/R Star 1 Star 2 BH Type B capture (star shredded) 5 × 106 107 1.5 × 107 (t − t0)/τ 1 10 100 1000 10000 xi,j/R x1,2 x1,3 x2,3 Type B capture (star shredded)

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Outcomes: "messy" capture

5 × 106 107 1.5 × 107 (t − t0)/τ 1 10 100 1000 10000 xi,j/R x1,2 x1,3 x2,3 Type B capture (star shredded) 9.75 × 106 107 1.025 × 107 1.05 × 107 1.075 × 107 (t − t0)/τ 1 10 100 1000 xi,j/R x1,2 x1,3 x2,3 Type B capture (star shredded)

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Three routes to a close MS-BH binary

  • 1. Undergo a dirty exchange and circularise

10 30 100 300 1000 a/R 0.2 0.4 0.6 0.8 1 e Inner ⋆ 1, type A Inner ⋆ 2, type A Inner ⋆ 1, type B Inner ⋆ 2, type B q = 2.75 R q = 3 R q = 4 R

Red circles:! messy exchanges! (star destroyed) Blue circles:! dirty exchanges! (star survives) Final binary! too wide to ! circularise

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Three routes to a close MS-BH binary

  • 2. Form a dirty triple and circularise

4 5 6 a/R 0.1 0.2 0.3 0.4 0.5 e Inner ⋆ 1, type A Inner ⋆ 2, type A Inner ⋆ 1, type B Inner ⋆ 2, type B q = 2.75 R q = 3 R q = 4 R Dirty triples, inner orbit properties, ai = 100 R

Blue: dirty Red: messy Artificial effect: ! tidal cut-off at 4 R

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Three routes to a close MS-BH binary

  • 3. A messy triple leads to common-envelope evolution

4 5 6 a/R 0.1 0.2 0.3 0.4 0.5 e Inner ⋆ 1, type A Inner ⋆ 2, type A Inner ⋆ 1, type B Inner ⋆ 2, type B q = 2.75 R q = 3 R q = 4 R Dirty triples, inner orbit properties, ai = 100 R

Red: messy

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Three routes to a close MS-BH binary

  • 3. A messy triple leads to common-envelope evolution

1000 10000 105 a/R 0.2 0.4 0.6 0.8 1 e Inner ⋆ 1, type A Inner ⋆ 2, type A Inner ⋆ 1, type B Inner ⋆ 2, type B q = 10 R q = 30 R q = 100 R q = 300 R Dirty triples, outer orbit properties, ai = 100 R

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Coming soon

  • 1. Numbers and rates
  • 2. Other stellar masses
  • 3. MS-BH + MS rather than MS-MS + BH