Cosmological Fast Radio Bursts

from Binary White Dwarf Mergers	

Kunihito Ioka (KEK)	

Kashiyama, KI & Mészáros 13	~10 yr ago 	

GRB Cosmology	

Massive star origin ⇒ High redshift GRBs	

Like QSO	

Like SN	

Star formation	

Reionization	

Metal, Dust	

Dark energy	…	

Larson & Bromm 02	

GRBs are useful	for probing high-z	

13/11/14	?	

z~10-30	

GRB	

z~8	QSO, galaxy	Fast	  Radio	  Burst	  by	  K.	  Ioka	  (KEK)	

2	

Radio Dispersion	

In a plasma, a light signal	

High energy photon	 is delayed	ω 2 = k 2 c 2 + ω p2
2plasma frequency	Low energy photon	 ω p = 4π ne = 5.63×10 4 n1 2 s−1m
Ionized region	

−2
Luminosity	

13/11/14	

t~Δt	%" ν % "
DM
Δt = 4.15 s $'' $ 3−3# 1 GHz & # 10 pc cm &Distortion in light curve	⇒ DM	Time	⇒ Reionization History	Fast	  Radio	  Burst	  by	  K.	  Ioka	  (KEK)	

3	

Dispersion Measure	is the column density of free electrons along light path	

Dispersion Measure	

13/11/14	

Dispersion Measure	↓	Reionization	

History	Reionization	

redshift	

Redshift	

Recombined electrons	

provide no DM	Fast	  Radio	  Burst	  by	  K.	  Ioka	  (KEK)	KI 03, Inoue 04	

4	

Intergalactic DM	

21+z
ν()
dt 1pΔt = ∫ dz
0dz 2 ⎡(1 + z )ν ⎤ 2⎣⎦ze2 1=×2
2π me c ν(1 + z ) dz
cn0 z
H 0 ∫0 ⎡Ω (1 + z )3 + Ω ⎤1 2Λ ⎦⎣ m

DMIGP	

including missing baryon	

DMGalaxy~30-103 pc cm-3	

KI 03	
13/11/14	

Fast	  Radio	  Burst	  by	  K.	  Ioka	  (KEK)	

5	

DM from Afterglow	

Distortion	

at t~Δt	⇒ DM	-2Δt∝ν 	

13/11/14	
KI 03	

Fast	  Radio	  Burst	  by	  K.	  Ioka	  (KEK)	

Unfortunately 	

radio afterglows	are not so bright	
6	

Fast Radio Bursts	
Thornton+ 13	64m Parkes radio telescope (New South Wales)	

High Time Resolution Universe (HTRU) Survey	

High latitude survey (-70 deg < b < -30 deg)	

ν=1.382 GHz, Δν=400 MHz/1024, Δθ~14 arcmin	

13/11/14	

F=0.6-8.0 Jy ms !!!	

Most luminous	

radio transients	

if cosmological	

Fast	  Radio	  Burst	  by	  K.	  Ioka	  (KEK)	

7	

Dispersion Measure	
Thornton+ 13	

Lorimer Burst	

δt∝DM・ν-2	

Galactic latitude	

DM=500-1000 cm-3 pc	
13/11/14	

Fast	  Radio	  Burst	  by	  K.	  Ioka	  (KEK)	

8	

Summary of FRB Obs.	
l DM=500-1000 cm-3 pc (z=0.5-1, dL~2-6Gpc)	

l Sν~Jy ⇒ Eiso~1038-40 erg	l δt=5.6ms,<4.3,1.4,1.1ms	

⇒ cδt(1+z)-1 < 1500(1+z)-1 km	l Rate~(1±0.5)×104/sky/day~10-3/yr/galaxy⇔ Supernova rate 10-2/yr/galaxy	l No repeated bursts so far	l No counterparts so far	

13/11/14	

Fast	  Radio	  Burst	  by	  K.	  Ioka	  (KEK)	

9	

Expected Rate	

Hassall+ 13	

Lorimer+ 13	
Trott+ 13	

Low frequency component SKA1 could 	

find an extragalactic burst every hour	
1 event/hour	

13/11/14	

Fast	  Radio	  Burst	  by	  K.	  Ioka	  (KEK)	

10	

Possible Origins	l RRAT (Rotating Radio Transient; intermittentpulsar)	

l Giant pulse from a msec/young pulsar	

Rees 77; Blandford 77; Kavic+ 08; Keane+ 12	l Evaporation of BH	l SN into a nearby star	Colgate+ 71,75; Egorov & Postnov 09	
l Magnetar giant flare	

Popov & Postnov 07; Thornton+ 13	
l Collapse of hypermassive NS	 Falcke & Rezzolla 13; Zhang 13	
Hansen & Lyutikov 01; Totani 13	l Binary NS mergers	

Cai+ 12	l Superconducting cosmic strings	

Loeb+ 12	l Nearby flaring stars	

13/11/14	

Fast	  Radio	  Burst	  by	  K.	  Ioka	  (KEK)	

11	

Binary White Dwarf Mergers?	
Kashiyama, KI & Meszaros 13	

l Massive WD	l SN Ia	

l Short GRB
via →NS	l WD pulsar
CR e± excess
	 Kashiyama+ 11	l GW sources	

13/11/14	

Fast	  Radio	  Burst	  by	  K.	  Ioka	  (KEK)	

lFRB?	

12	

Minimum Requirements	

l Energetics	

l Timescale	l Event rate	
13/11/14	

Fast	  Radio	  Burst	  by	  K.	  Ioka	  (KEK)	

13	

Energetics	
Magnetic Energy	 Bobs,max~109G	23B 4π r
432 3EB ≈×~ 2 ×10 erg B9 r8.7
8π
3
WD-WD merger ⇒ Differential rotation ⇒ B	GM 2Emax ≈≈ 10 50 erg
r

13/11/14	

Fast	  Radio	  Burst	  by	  K.	  Ioka	  (KEK)	

Loren-Aguilar+ 09, Ji+ 13	v
−1 −3 2Ω ≈ ~ 1 s r8.7
r14	

Timescale	
WD radius	−1−18cδ t (1+ z ) ≤ 1.5 ×10 (1+ z ) cm < 108.7cm	
12# rΩ &rcap ≈ r % ($ c '732
8.7

120~ 6.7 ×10 cm r Ωrcap
32 12~ 2.3 ms r8.7 Ω0c
13/11/14	

Fast	  Radio	  Burst	  by	  K.	  Ioka	  (KEK)	

15	

Event Rate	
WD-WD merger rate	
−2

RWD2 ~ 10 −10−3yr−1galaxy−1~4000 WDs in SDSS	

Radial velocity ⇒ Binary fraction & distribution n(a)∝aα	Badenes & Maoz 12	

13/11/14	

Fast	  Radio	  Burst	  by	  K.	  Ioka	  (KEK)	

16	

Binary White Dwarf Mergers?	
Kashiyama, KI & Meszaros 13	

13/11/14	

Fast	  Radio	  Burst	  by	  K.	  Ioka	  (KEK)	

l Energetics	

EB~1040erg	

l Timescale	

rcap/c~ms	l Event rate	

~SN Ia	l SN Ia as a 	counterpart?	

17	

Counterparts	
l Supernova Ia (Double degenerate model)	

LX<1047erg/s for ~100sec	l X-ray debris disk	
Swift for nearby FRBs	

13/11/14	

Fast	  Radio	  Burst	  by	  K.	  Ioka	  (KEK)	

Loren-Aguilar+ 09, recently Beloborodov 13	

18	

FRB Cosmology	KI 03	

McQuinn 13	

l Reionization	

l Missing baryon	

l Dark energy, 
cosmological parameters	
1+ z ) dz
3cH 0Ωb z(DM IGP =∫8π Gm p 0 #Ω 1+ z 3 + Ω %1 2)
Λ&$ m(

Fast radio bursts 	c (1+ z ) zdz
dL =∫0 #12ascosmologicaltools	

3H0%Λ$Ωm (1+ z ) + Ω
13/11/14	
Fast	  R&adio	  Burst	  by	  K.	  Ioka	  (KEK)	
19	
New frontier?	

Counterparts to GW	
Gravitational Wave Sources	

Neutrino	?	
!!!	
21	  Nov	  2013	

Gravitational wave	?	

?	

?	 ?	

U.	  Tokyo	  Seminar	  by	  Kunihito	  IOKA	  (KEK)	

X-ray	

Gamma-ray	

IR-Opt	20	

Radio	

Relativistic Shock Breakout	
RelaHvisHc	

Kyutoku, KI & Shibata 12	
13/11/14	

Not resolved yet	

Fast	  Radio	  Burst	  by	  K.	  Ioka	  (KEK)	
21	
by numerical simulation	

Relativistic ShockAcceleration	ρ	Γ sh ∝ ρAfter breakout,	

shocked matter 	accelerates to	−α rela3
α rela ≈ 3 −2≈ 0.232

1+ 3shΓf ≈ Γby converting heat 	into motion	
13/11/14	

Fast	  Radio	  Burst	  by	  K.	  Ioka	  (KEK)	

Johnson & McKee 71	r	22	Relativistic Outflow	
1050

n=3, Msh=10-4
M-5 sunn=3, Msh=10-5 Msun
n=4, Msh=10-5 Msun
n=6, Msh=10-6 Msun
n=3, Msh=10 Msun

E(>`K) (erg)

1049
1048

v>>vesc~0.3c!!!	

1047
1046
1045
1044

escape velocity
for M* = 2.8 Msun
and R* = 15 km
1

13/11/14	
KI & Shibata 12	
Kyutoku,

10

Fast	  Radio	  Burst	  by	  K.	  Ioka	  (KEK)	

`K100

1000

23	

Early & High-Energy Emission	

Macronova	

Radio flare	

13/11/14	

Fast	  Radio	  Burst	  by	  K.	  Ioka	  (KEK)	

24	

Summary	l Fast Radio Burst	

Thornton+ 13	l Dispersion Measure ⇒ Cosmological?	

KI 03	l Binary White Dwarf Merger	

– Energetics ✔, Timescale ✔, Event Rate ✔

– SN Ia, X-ray debris disk	l FRB Cosmology	

Kashiyama, KI & Mészáros 13	

l Ultrarelativistic EM Counterpart to NS2	Kyutoku, KI & Shibata 13	
13/11/14	

Fast	  Radio	  Burst	  by	  K.	  Ioka	  (KEK)	

25	

ThankYou	BH-NS Merger	
©Kyutoku	

Only Ejecta	

x-z plane, only ejecta	
Full GR	

Q=5	

χ=0.75	

H４13/11/14	
EOS	

Fast	  Radio	  Burst	  by	  K.	  Ioka	  (KEK)	

Kyutoku, KI & Shibata 13	27	Anisotropic Mass Ejection	

1θ ej ≈
5

ϕ ej ≈ π
Kyutoku, KI & Shibata 13	
13/11/14	

Viewing angle diversity	

Polarization	

Proper motion	

Fast	  Radio	  Burst	  by	  K.	  Ioka	  (KEK)	

28	

Spin Down Luminosity	
2 64BrΩ38−1 2 6443 erg/s	
<<10Lspin ≈~1.7×10ergs
BrΩ
9 8.7 03c

B reconnection 	⇒ FRB	

like solar flares,	

magnetar flares	

13/11/14	

Fast	  Radio	  Burst	  by	  K.	  Ioka	  (KEK)	

29	

Acceleration	
2 3BΩ r162 3
Φ max ≈~ 2.5 ×10 Volt B9Ω0 r8.7
22c
⇒ e± production	

⇒ Coherent	

radio emission	

13/11/14	

Fast	  Radio	  Burst	  by	  K.	  Ioka	  (KEK)	

30	

Beaming	

Kashiyama, KI & Meszaros 13	

Injection 	≠ Emission	

13/11/14	

Fast	  Radio	  Burst	  by	  K.	  Ioka	  (KEK)	

31	

Brightness Temperature	
2⊥2

2

41

−243 emi,10π r 2νFν =kT
2d c
T ~ 3×10 K L r⇒ Coherent emission	

P~|E|2~|E1+E2+E3+…+EN|2	~N|E1|2	(incoherent)	

2|E |2	~N	(coherent)
1
13/11/14	
Fast	  Radio	  Burst	  by	  K.	  Ioka	  (KEK)	

32	

Curvature Radiation	
3cνc ≈ γ
4π rc
33 −1
3 c,10~ 0.72 GHz γ r

13 13
9 c,10γ ≥ 1100ν r
13/11/14	

Fast	  Radio	  Burst	  by	  K.	  Ioka	  (KEK)	

33	

Luminosity	
Ltot ≈ ( Pc N2coh)× N

pat

2γ 4 e 2 c−17−14 −2Pc ~~5×10ergsγ
3 rc,1023rc
4 2 c
2N coh ≈ ne ×Vcoh ≈ ne × 2 remi ~ ne × 2 ×1016 cm 3 γ 3−5rc,10 remi,10γ
νcVemi
1122N pat ≈≈4π fremiδ remi ~× 9 ×10 28 cm 3 fremi,10
δ remi,7.8
Vcoh Vcoh
Vcoh

Ltot ~ 4 ×10
13/11/14	

42−1

2−1 −1 4e,7 3 c,10 emi,10erg s fn γ r r
Fast	  Radio	  Burst	  by	  K.	  Ioka	  (KEK)	

δ remi,7.834	

Electron Density	
71 2 1 2 1 2 −2
43 3 c,10 emi,10ne ~ 2 ×10 cm L γ r r−1 2emi,7.8

δr

Necessary multiplicity	nene3−1−1
κ GJ ==~ 8 ×10 ne,7 Bemi,5Ω0nGJ BemiΩ 2π ce
Plasma frequency limit	
12γ $ 4π ne# e 'neνc ≥ ν p ≈&) , ne# =2π % me (γ27ne ≤ 0.6 ×10 cm

13/11/14	

−35 −2
3 c,10γ r

Fast	  Radio	  Burst	  by	  K.	  Ioka	  (KEK)	

35	

Induced Compton	

Melrose 71	

Wilson & Rees 78	

Lyubarsky 08	

Compton scattering is enhanced by photons	

To evade the induced Compton	
3 14 3 14
3 14c,10 emi,10 e,7γ ≥ 2000 r
13/11/14	r

Fast	  Radio	  Burst	  by	  K.	  Ioka	  (KEK)	

n36