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

Electromagnetic Radiations From Binary Black Holes

Shigeo S. Kimura

Collaborators Kenji Toma, Sanemichi Takahashi (Tohoku Univ.) Kohta Murase, Peter Meszaros (PSU)

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.

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 detected the gravitational waves

from merging black holes (BHs)

• Revealing existence of BH-BH binaries of MBH ~ 30 Msun

LIGO collaboration 16

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• ~
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• Formation scenarios
• Dynamical formation

Formation in star cluster through 3-body interactions

Time (Myr) 0.0000 3.5445 3.5448 3.8354 3.8354 5.0445 5.0445 5.3483 5.3483 MS HG He star BH BH BH BH BH 96.2M 92.2M 42.3M 39.0M 35.1M 35.1M 36.5M 36.5M 36.5M a (R) e 60.2M 59.9M 84.9M 84.7M 84.7M 82.2M 36.8M 34.2M 30.8M 2,463 2,140 3,112 3,579 3,700 3,780 43.8 45.3 47.8 0.15 0.00 0.00 0.00 0.03 0.03 0.00 0.00 0.05 MS MS MS MS MS CHeB He star He star BH Roche-lobe overfmow Zero-age main sequence Direct collapse Direct collapse HG

• r

CHeB Common envelope

• Binary evolution

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• ~
• =
• =
• <
• Rodriguez+ 16

Belczynski+ 16

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• ~
• =
• =
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• Formation scenarios
• Dynamical formation

Formation in star cluster through 3-body interactions

Time (Myr) 0.0000 3.5445 3.5448 3.8354 3.8354 5.0445 5.0445 5.3483 5.3483 MS HG He star BH BH BH BH BH 96.2M 92.2M 42.3M 39.0M 35.1M 35.1M 36.5M 36.5M 36.5M a (R) e 60.2M 59.9M 84.9M 84.7M 84.7M 82.2M 36.8M 34.2M 30.8M 2,463 2,140 3,112 3,579 3,700 3,780 43.8 45.3 47.8 0.15 0.00 0.00 0.00 0.03 0.03 0.00 0.00 0.05 MS MS MS MS MS CHeB He star He star BH Roche-lobe overfmow Zero-age main sequence Direct collapse Direct collapse HG

• r

CHeB Common envelope

• Binary evolution

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• ~
• =
• =
• <
• difficult to distinguish these scenarios
• nly from GW observations

Electromagnetic Radiations are important

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)

• Accretion may take place when

BBHs are born and/or merging

Balbus & Hawley 91 Suzuki & Inutsuka 14

Outline

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

Binary Evolution scenario

• massive star binary 


—> Binary Black Hole

• First, Primary —> BH
• Secondary becomes giant

—>Common envelope

• Ejection of CE


—> close BH-WR binary

• WR collapses to BH


—> BBH formation

• Direct Collapse


= Failed Supernovae

Time (Myr) 0.0000 3.5445 3.5448 3.8354 3.8354 5.0445 5.0445 5.3483 5.3483 MS HG He star BH BH BH BH BH 96.2M 92.2M 42.3M 39.0M 35.1M 35.1M 36.5M 36.5M 36.5M a (R) e 60.2M 59.9M 84.9M 84.7M 84.7M 82.2M 36.8M 34.2M 30.8M 2,463 2,140 3,112 3,579 3,700 3,780 43.8 45.3 47.8 0.15 0.00 0.00 0.00 0.03 0.03 0.00 0.00 0.05 MS MS MS MS MS CHeB He star He star BH Roche-lobe overfmow Zero-age main sequence Direct collapse Direct collapse HG

• r

CHeB Common envelope

Kinugawa+14, Belczynski+ 16

Failed Supernovae

• ProtoNeutron Star forms when massive star collapses
• Neutrino loss—> Binding energy decrease


—> shock propagation—> envelope ejection ~ 0.01Msun

Lovegrove & Woosley 13

ν ν

PNS

~~~~~~~> ~~~~~~~> ~~~~~~~> ~~~~~~~>

ν ν

• utflowing

envelope collapsing core

Nadyozhin 80

Bondi-Hoyle Accretion

• The primary BH accretes the failed SN ejecta by 


Bondi-Hoyle accretion rate

˙ MB-H ≈ 4πR2

accρej,m

• v2

a + v2

• rb.~ 4.2x1025 g/s >> ṀEdd

r

Racc = GMBH v2

a + v2

• rb

,

BH accretion Column

Edgar 04 SSK+ in prep.

va: ejecta velocity vorb: orbital velocity

Radiation-driven Outflow

• Accreted material

forms a disk

• super-Eddington accretion rate


—> A radiation-driven outflow

Huarte-Espinosa+13⭐

wind

• rbital motion

Jiang+ 2014

v/c

Lw ≈ 1 2fw ˙ MB-Hv2

w.~ 6.3x1044 erg/s

Outflow-driven SNe

• Radiation-driven outflow pushes the ejecta


—> sub-energetic supernova

Ew ~ 1.4x1049 erg

˙ MB-H ≈ 4πR2

accρej,m

• v2

a + v2

• rb.

dEkin dt = Eint tdyn ,

dEint dt = fiLw − Eint tdyn − Lph,

Energy eq. EoM

dRej dt = vej.

Lph = radEint tph = Eint (1 + τej)Rej/c

Assumption: Spherical Symmetric Homologas expansion

ρej,m ≈ 3mej 4πa3 t tarr −3

where va = a/t.

SSK+ in prep.

Time Evolution

• Duration: a few days
• Temperature: 104 — 105 K

va > vorb va < vorb L [erg/s] t [day] t [day] 10 1 10 1 T [K] 1042 105

SSK+ in prep.

Light Curve

• 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

SSK+ in prep.

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

• Color is bluer than the usual supernovae

SSK+ in prep.

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.

• However, some consider

this signal is a false alert.

´

• ´
• Figure 2. Model-dependent count rates detected as a function of time

Connaughton + 16 Zhang+16, Greiner+16, Xiong 16

• Theoretical studies show

possible models.

• However, these models

seem unlikely.

Perna+16, Loab 16, Januik+17 Lyutikov+16, SSK+17, Dai+16

Timescale

• The material accretes to BH in the viscous time 

• The BBH merges in a merger time

• tvis ~ 3x104 s << tmer ~ 4x1015 s @ Rini~1012 cm, M~30 Msun


—> The material completely accretes to BH if angular momentum is efficiently transported by MHD turbulence

tmer = 5 512 c5 G3 R4

ini

M3

BH

tvis = 1 αK rout H 2

a) dead disk survives until tmer < tvis 
 (~1 s before the merger event).
 b) rapid accretion can produce GRB.

~ = = >

• a

= ´

• 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+2016 propose the dead disk model for Fermi GBM event

Dead disk model

Perna+16

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

Motivation

We examine the dead disc model, taking account of the above processes more carefully.

Tidal torque

Orbits of test particles Radial profile of tidal torque Tidal torque r/Rini

Rini asepRini

disk BH BH

Tidal torque diverges at tidal truncation radius → The disk cannot expand outward beyond there Non-Axisymmetric gravity induces torque

Ishikawa & Osaki 94

Disk Evolution in BBH

Σ [g/cm2 ] r [cm] md [Msun] t [1/Ω]

109 108 107 10-3 10-5 1010 1011 103 101

∂Σ ∂t = 1 r ∂ ∂r

• 1

dj/dr ∂ ∂r

• νΣr3 dΩ

dr

• ,

˙

Ṁ=0 at r=rout

e, Qvis = Qrad,

tvis ~ 3x104 s << tmer ~ 4x1015 s @ Rini~1012 cm
 —> separation does not change during initial evolution

Σ = Σ0 (t/tini)−3/2 (r/rout)−3/5

T = T0 (t/tini)−1 (r/rout)−9/10

md = m0 (t/tini)−3/2

SSK+17

Formation of Dead disk

Λ = v2

A

ηΩK > 1,

Condition for MRI activation:

χ2

e

1 − χe = 1 n 2πmekBT h2 3/2 exp

• − Ei

kBT

• ,

tion discs, where the Ohm η = 234(T/1K)1/2 χ−1

e cm2s−1 ( 2

2c2

Ohmic resistivity Saha’s equation

T > Tdead ~3000K Thermal instability@T~ 40000K
 —> rapid temperature drop to T<Tdead mdead ~ 5x10-7 Msun Dead disk formation

Lasota‘01

tdead ~ a few years

Thermal equilibrium curves

Blae+94 Bell&Lin 94

Disk Revival

• Separation decreases due to GW 


—> The dead disk shrinks due to tidal torque
 —> Disk heats up due to mass inflow
 —> Disk Revival: MRI becomes active (T > Tdead)

• Disk revival condition: Q+ ~ Ṁsd Ω2 > Qrad(Tdead)


—> Rrev ~ 1.4x1011 cm, Ṁrev~2.6x1014 g/s << ṀEdd

• Time until merger: tmer - trev ~ 1012 s

Rsep asepRsep Rsep asepRsep

vgw

〜 〜 ＞

GW

Impossible to explain short GRBs

Evolution of Revival Disk

Tidal torque controls Ṁ of revival disk

˙ MGW = −2πroutΣoutasepvGW = −7mdvGW 5Rsep ,

md = mdead tmer − t tmer − trev 7/20 .

˙ MGW = 7mdead 20(tmer − trev) tmer − t tmer − trev −13/20 ˙

Solve dmd/dt = - ṀGW GW determines evolution of Rsep

Rsep = Rrev tmer − t tmer − trev 1/4 ,

ṀGW increases with time and 
 ṀGW can be super Eddington before merger

Jet launching

• High Accretion rate


—> Geometrically thick 
 & strong magnetic field
 —> jet can be launched

• Jet launch condition:


ṀGW > Ṁjet ~ 10LEdd/c2

• Luminosity of Jets:


Ljet ~ ṀGWc2

• ´
• r

µ

f

r r =

• 5

r =

• 5

) r =

• r

~ ~

Takahashi & Ohsuga 16

Emission from Jet

・Internal Shock: 10% of Ljet goes to X-ray

・Afterglow: 10% of LAG goes to optical

LAG ∼ Ejet(t) t − tjet = t

tjet Ljetdt′

t − tjet ,

− jet

AG ∼ ˙

MGWc2 ∼ 10LEdd

estimate with simplest modeling Fband ~ 0.1 Ljet / (4 π dL2)

Detectable by optical followup and/or X-ray monitoring

J-GEM, Pan-STARRS MAXI, SWIFT

model MBH[M] Rini [cm] (tmer − tjet) [s] LAG [erg s−1] TAG [s] dL,limit [Mpc] A 30 3 × 1012 3.0×105 3.8×1040 1.5×103 19 B 103 3 × 1013 4.7×106 1.3×1042 1.0×104 1.1×102 C 105 1015 4.36×108 1.3×1044 2.1×105 1.1×103

Fband [erg/s/cm2] (tmer - t) [s]

10 100 10-9 10-8

Light curves of internal shock emission

SSK+17

Short Summary II

• Evolution of accretion disk in

BBHs are shown in the left panel.

• Disk becomes dead when the

disk sufficiently cools down.

• The dead disk revives due to

tidal torque ~105 yr before the merger event.

• EM counterparts are detectable

before the merger if merger happens around 10 Mpc.

Rrev Rini !rev mdead !dead

I II III-i

!t-3/2 !t-5/2

initial evolution dead disk revival disk jet launched

trev tjet tmer

!jet

t md ! Rsep

• !dead

t III-ii

SSK+17

Outline

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

Summary

• Detection of GW reveals existence of BBHs.
• BBHs can emit EM radiation when they are born or

they merge.

• Sub-energetic SNe from newborn BBHs are

detectable by current optical transient surveys.

• Dead disk revives ~105 years before the merger,

and it produces not GRB like burst but weak transient of longer duration.

〜 〜 ＞

GW