Electromagnetic Radiations From Binary Black Holes Shigeo S. Kimura - PowerPoint PPT Presentation

Electromagnetic Radiations From Binary Black Holes Shigeo S. Kimura Center for Particle Astrophys. PSU (IGC Fellow) Dept. Astronomy & Astrophys., PSU Dept. Physics, PSU ref) SSK, S. Z. Takahashi, & K. Toma, 2017, MNRAS, 465, 4406 SSK, K. Murase, P. Meszaros in prep. Collaborators Kenji Toma, Sanemichi Takahashi (Tohoku Univ.) Kohta Murase, Peter Meszaros (PSU)

Outline • Introduction • sub-Energetic Supernovae from Newborn BBHs • Evolution of Accretion Disks in BBHs • Summary

Outline • Introduction • sub-Energetic Supernovae from Newborn BBH • Evolution of Accretion Disks in BBHs • Summary

Detection of GWs LIGO collaboration 16 • LIGO collaboration detected the gravitational waves from merging black holes (BHs) • Revealing existence of BH-BH binaries of M BH ~ 30 M sun

Formation scenarios • Dynamical formation • Binary evolution Belczynski+ 16 Time (Myr) a ( R � ) e Zero-age main sequence Rodriguez+ 16 0.0000 MS 96.2 M � MS 60.2 M � 2,463 0.15 < � Formation in Roche-lobe over fm ow star cluster 3.5445 HG 92.2 M � MS 59.9 M � 2,140 0.00 through 3-body interactions � HG 3.5448 42.3 M � MS 84.9 M � 0.00 or 3,112 CHeB 3.8354 He star 39.0 M � MS 84.7 M � 0.00 3,579 Direct collapse 3.8354 BH 35.1 M � MS 84.7 M � 0.03 3,700 Common envelope 5.0445 BH 35.1 M � CHeB 82.2 M � 0.03 3,780 5.0445 BH 36.5 M � He star 36.8 M � 0.00 43.8 5.3483 BH 36.5 M � He star 34.2 M �� 0.00 45.3 < Direct collapse � � 5.3483 BH 36.5 M � BH 30.8 M � 0.05 47.8 � � < � ~ � = � = � � � � < � � � � ~ � = � = � � �

are important difficult to distinguish these scenarios Electromagnetic Radiations only from GW observations Formation scenarios • Dynamical formation • Binary evolution Time (Myr) a ( R � ) e Zero-age main sequence 0.0000 MS 96.2 M � MS 60.2 M � 2,463 0.15 < � Formation in Roche-lobe over fm ow star cluster 3.5445 HG 92.2 M � MS 59.9 M � 2,140 0.00 through 3-body interactions � HG 3.5448 42.3 M � MS 84.9 M � 0.00 or 3,112 CHeB 3.8354 He star 39.0 M � MS 84.7 M � 0.00 3,579 Direct collapse 3.8354 BH 35.1 M � MS 84.7 M � 0.03 3,700 Common envelope 5.0445 BH 35.1 M � CHeB 82.2 M � 0.03 3,780 5.0445 BH 36.5 M � He star 36.8 M � 0.00 43.8 5.3483 BH 36.5 M � He star 34.2 M �� 0.00 45.3 < Direct collapse � � 5.3483 BH 36.5 M � BH 30.8 M � 0.05 47.8 � � < � ~ � = � = � � � � < � � � � ~ � = � = � � �

Accretion onto BHs Gravitational energy 
 • —> Radiation energy Angular momentum 
 • —> Accretion disk Angular momentum transport • is necessary for continuous accretion 
 —> MHD turbulence made by magnetorotational instability (MRI) Balbus & Hawley 91 Accretion may take place when • BBHs are born and/or merging Suzuki & Inutsuka 14

Outline • Introduction • sub-Energetic Supernovae from Newborn BBH • Evolution of Accretion Disks in BBHs • Summary

Binary Evolution scenario Kinugawa+14, Belczynski+ 16 Time (Myr) a ( R � ) e Zero-age main sequence • massive star binary 
 0.0000 MS 96.2 M � MS 60.2 M � 2,463 0.15 —> Binary Black Hole Roche-lobe over fm ow 3.5445 HG 92.2 M � MS 59.9 M � 2,140 0.00 • First, Primary —> BH • Secondary becomes giant HG 3.5448 42.3 M � MS 84.9 M � 0.00 or 3,112 CHeB —>Common envelope • Ejection of CE 
 3.8354 He star 39.0 M � MS 84.7 M � 0.00 3,579 Direct collapse 3.8354 BH 35.1 M � MS 84.7 M � 0.03 3,700 —> close BH-WR binary • WR collapses to BH 
 Common envelope 5.0445 BH 35.1 M � CHeB 82.2 M � 0.03 3,780 —> BBH formation • Direct Collapse 
 5.0445 BH 36.5 M � He star 36.8 M � 0.00 43.8 5.3483 BH 36.5 M � He star 34.2 M �� 0.00 45.3 = Failed Supernovae Direct collapse 5.3483 BH 36.5 M � BH 30.8 M � 0.05 47.8

Failed Supernovae Nadyozhin 80 ν Lovegrove & Woosley 13 ν ~~~~~~~> outflowing ~~~~~~~> envelope PNS ~~~~~~~> ~~~~~~~> collapsing core ν ν • ProtoNeutron Star forms when massive star collapses • Neutrino loss—> Binding energy decrease 
 —> shock propagation—> envelope ejection ~ 0.01M sun

Bondi-Hoyle Accretion • The primary BH accretes the failed SN ejecta by 
 Bondi-Hoyle accretion rate SSK+ in prep. v a : ejecta velocity v orb : orbital velocity Edgar 04 GM BH R acc = , a + v 2 v 2 orb BH accretion Column r � orb . ~ 4.2x10 25 g/s >> Ṁ Edd ˙ M B-H ≈ 4 π R 2 a + v 2 v 2 acc ρ ej , m

Radiation-driven Outflow • super-Eddington accretion rate 
 • Accreted material —> A radiation-driven outflow forms a disk v/c Jiang+ 2014 Huarte-Espinosa +13 ⭐ wind orbital motion L w ≈ 1 2 f w ˙ M B-H v 2 w . ~ 6.3x10 44 erg/s

Outflow-driven SNe Assumption: Spherical Symmetric Homologas expansion � t � − 3 ρ ej , m ≈ 3 m ej where v a = a/t . 4 π a 3 t arr EoM dE kin = E int dR ej , = v ej . dt t dyn dt Energy eq. dE int = f i L w − E int − L ph , dt t dyn L ph = � rad E int E int = t ph (1 + τ ej ) R ej /c � ˙ M B-H ≈ 4 π R 2 a + v 2 v 2 orb . SSK+ in prep. acc ρ ej , m • Radiation-driven outflow pushes the ejecta 
 E w ~ 1.4x10 49 erg —> sub-energetic supernova

Time Evolution L [erg/s] T [K] v a > v orb v a < v orb 10 42 10 5 t [day] 1 10 1 10 t [day] SSK+ in prep. • Duration: a few days • Temperature: 10 4 — 10 5 K

Light Curve SSK+ in prep. • Event rate: similar to LIGO ~ 10–100 Gpc -3 yr -1 
 —> expected distance ~300 Mpc 
 —> ~22 mag. @ 300 Mpc 
 —> detectable by Current optical transient survey

Caveat • Spherical symmetric treatment is not accurate 
 a) Effect of the outflow on ejecta 
 b) Finite binary separation • To investigate these effect, we need 3D (radiation) hydrodynamic simulation with feedback of outflows from the BH, which might be similar to the galaxy formation simulation with AGN feedback.

Short Summary I Accretion of ejecta onto primary BH produces 
 • a energetic outflows, which leads to sub-energetic SNe Duration of the SNe is a few days, 
 • absolute magnitude is ~ -15 SSK+ in prep. Color is bluer than the usual supernovae •

Outline • Introduction • sub-Energetic Supernovae from Newborn BBH • Evolution of Accretion Disks in BBHs • Summary

EM Counterparts of GWs • Fermi GBM reported possible EM counterparts. Connaughton + 16 • However, some consider this signal is a false alert. Zhang+16, Greiner+16, Xiong 16 • Theoretical studies show possible models. Perna+16, Loab 16, Januik+17 • However, these models seem unlikely. Lyutikov+16, SSK+17, Dai+16 Figure 2. Model-dependent count rates detected as a function of time - ´ - ´

Timescale • The material accretes to BH in the viscous time 
 � r out 1 � 2 t vis = α� K H • The BBH merges in a merger time 
 c 5 R 4 5 ini t mer = M 3 G 3 512 BH • t vis ~ 3x10 4 s << t mer ~ 4x10 15 s @ R ini ~10 12 cm, M~30 Msun 
 —> The material completely accretes to BH if angular momentum is efficiently transported by MHD turbulence

Dead disk model Perna+2016 propose the dead disk model for Fermi GBM event • If the disk cools down and becomes neutral, the MHD turbulence becomes weak, and make a “dead disk” where angular momentum transform is inefficient. Perna+16 a) dead disk survives until t mer < t vis 
 (~1 s before the merger event). 
 b) rapid accretion can produce GRB. � > � ~ = = = ´ a -

Motivation Perna’s model seems to misestimate or ignore 
 i) tidal torque from the companion 
 ii) condition for MRI activation/inactivation 
 iii) mass inflow due to separation decrease We examine the dead disc model, taking account of the above processes more carefully.

Tidal torque Non-Axisymmetric gravity induces torque Ishikawa & Osaki 94 Tidal torque r/R ini Orbits of test particles Radial profile of tidal torque Tidal torque diverges at tidal truncation radius → The disk cannot expand outward beyond there disk BH BH a sep R ini R ini

Disk Evolution in BBH SSK+17 Σ [g/cm 2 ] t vis ~ 3x10 4 s << t mer ~ 4x10 15 s @ R ini ~10 12 cm 
 10 9 —> separation does not change during initial evolution 10 8 10 7 � � � � ∂ Σ ∂ t = 1 ∂ 1 ∂ ν Σ r 3 d Ω r [cm] , 10 10 10 11 r ∂ r dj / dr ∂ r dr m d [M sun ] ˙ e, Q vis = Q rad , Ṁ =0 at r=r out 10 -3 m d = m 0 ( t/t ini ) − 3 / 2 10 -5 Σ = Σ 0 ( t/t ini ) − 3 / 2 ( r/r out ) − 3 / 5 t [1/ Ω ] 10 3 10 1 T = T 0 ( t/t ini ) − 1 ( r/r out ) − 9 / 10

Formation of Dead disk v 2 Condition for MRI activation: A Λ = > 1 , η Ω K Saha’s equation � 2 π m e k B T Ohmic resistivity � 3 / 2 χ 2 tion discs, where the Ohm � � = 1 − E i e exp , e cm 2 s − 1 ( η = 234 ( T / 1K ) 1 / 2 χ − 1 h 2 1 − χ e n k B T 2 2 c 2 Blae+94 T > T dead ~3000K Thermal equilibrium curves Lasota‘01 Thermal instability@T~ 40000K 
 —> rapid temperature drop to T<T dead Dead disk formation Bell&Lin 94 m dead ~ 5x10 -7 M sun t dead ~ a few years