what ligo o1 results have taught us about astrophysics? · population i/ii: classical bh-bh mergers...

Astrophysical implicationsPopulation III stars: BH-BH mergers

Population I/II: classical BH-BH mergers

What LIGO O1 results have taught us aboutastrophysics?

Chris Belczynski1T.Bulik1, D.Holz

R.O’ShaughnessyC.Fryer, E.Berti

A.Ruiter, W.Gladysz1, G.Wiktorowicz1, A.Heger, S.WoosleyT.Ryu, R.Perna, T.Takamitsu

1Astronomical Observatory, Warsaw University

– Astrophysical implications: any? or just limited?

– BH-BH from Pop III stars: no big deal...

– Classical Pop I/II BH-BH formation model: major update

Chris Belczynski The Astrophysics of BH-BH Mergers (Aspen: 2017)



BH-BH formation: broad perspective

First astro-implication of LIGO detections: outbreak of models

Primordial BH-BH: density fluctuations after Big Bang

PopIII BH-BH: first massive stars (⇠ 1% of stars in Universe)

PopII/I BH-BH: classic field binary evolution (⇠ 90%)

PopII/I BH-BH: rapid rotation (homogeneous evol.) (⇠ 10%)

PopII/I BH-BH: dynamics/globular clusters (⇠ 0.1%)

exotic BH-BH: e.g., single star core splitting (?)

before LIGO detections: NS-NS dominant source – a conceptual mistake




modeling: synthetic universe




BH-BH O1 detections: lessons learnt?

Astro-implications: model/origin limited

Primordial BHs: dark matter component? (CMB?)

PopIII BHs: star formation & evolution at zero metallicity (halo?)

Dynamical BHs: revised cluster dynamics (NS systems?)

Homogeneous evol. BHs: non-standard stellar evolution(re-ionization/chemical enrichment?)

Classical evol. BHs: Common Envelope, BH mass & natal kick(spins?)

LIGO O1 detections: confirmation of massive BH existence – butnothing new learnt yet... without the (lacking) info on the origin




Star formation history: Population III (first) stars

0 5 10 15 20 25 30 35 40

cosmic time [Gyr]13.5 1.0 0.5 0.2 0.06

Pop I/II: uncertain for z>2, Pop III: much smaller contribution




Population III binary initial conditions:IMF orbital separations

0 20 40 60 80 100 120 140 160 0 1 2 3 4 5 6 7 8

0

25000

50000

75000

100000

125000

150000

M10 – Pop I/II (Sana et al. 2012)FS1 – Pop III: large dark matter halos (2000 AU)FS2 – Pop III: small dark matter halos (10-20 AU)

Pop III: very different initial conditions than for PopI/II...




Pop III BH-BH merger rate history:

0 5 10 15 20 25 30 35 40 45

z=2aLIGO horizon

Pop III BH-BH rates: 2.5 orders below LIGO, 4 orders below Pop I/II




Formation of massive BH-BH merger: Pop I/II

TIME [Myr]

0.0000

3.5445 3.5448 3.8354 3.8354 5.0445 5.0445 5.3483 5.3483 10,294

MS

HG He star BH BH BH BH BH

96.2 M⊙

92.2 M⊙ 42.3 M⊙ 39.0 M⊙ 35.1 M⊙ 35.1 M⊙ 36.5 M⊙ 36.5 M⊙ 36.5 M⊙

a [R⊙] e

60.2 M⊙

59.9 M⊙ 84.9 M⊙ 84.7 M⊙ 84.7 M⊙ 82.2 M⊙ 36.8 M⊙ 34.2 M⊙ 30.8 M⊙

2463

2140

3112

3579

3700

3780

43.8 45.3

47.8

0

0.15

0.00

0.00

0.00

0.03

0.03

0.00 0.00

0.05 0.00

MS

MS MS MS MS CHeB He star He star BH

RLOF

CE

ZAMS

DIRECT BH

DIRECT BH

MERGER

HG or CHeB

low metallicity: Z < 10%Z�

CE: during CHeB

delay: 10 Gyr or 2 Gyr

O1 horizon: z = 0.7(inspiral-merger-ringdown)

total merger mass: 20–80 M�

aligned BH spins: tilt= 0 deg?

BH spin: a = 0.0 -> a = 0.126a = 0.5 -> a = 0.572a = 0.9 -> a = 0.920

credit: Wojciech Gladysz (Warsaw)




BH-BH mergers: LIGO 44 days of O1 (70 Mpc)

0 20 40 60 80 100 120 140 160 180

O1 upper limits

standard model M1

rateLIGO

BH-BHonly

M1

M4

M2

M3

LIGO BH-BH merger rate: 9–240 Gpc�3 yr�1

GW150914: 36 + 29 M�, LVT151012: 23 + 13 M�, GW151226: 14 + 8 M�


what ligo o1 results have taught us about astrophysics? · population i/ii: classical bh-bh mergers...

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