Establishment of Imaging Spectroscopy in MeV
gammas & its application to GRB detections

130cm
ETCC

COMPTEL’s MeV sky map

COMPTEL~30 objects/10 years~1 m

V. Schönfelder+ (A&AS, 2000)

CONTENTS

1. Point Spread Function in MeV region
2. Imaging Spectroscopy by ETCC
Two big problems in MeV Astro.
3. Imaging Observations for GRBs
1. Imaging is very difficult+Kilonova
2. Huge background
1. Summary
03/Mar./2017 @ Chiba Univ.

T. Tanimori on behalf of SMILE-Project,
Cosmic-ray group, Physics-II Division,Kyoto Universty, JapanLine gammas from SN Ia SN2014J (INTEGRAL-SPI)SPI: Codded Mask 19 xGe

FoV ~1 str

S.W.D

D.W.D

E.Churazov(IKI,MPA)

SN2014J

Tanimori et al., ApJ (2015), 810, 28
Nature,512,（2014）

qT.Siegert,(MPE,Garching)

fy
SWIFT

SPI Effective Area 65cm2@1MeV#of Photons ; 5x10-6x65cm2x30keVx5x106s ~4x104g
From ~4s detection BG Estimation ->~108g at 60keV band
If BG were reduced by 3 orders
BG ~105 => 4x104/√(105) > 100s
PSF (radius=2o) -> ~10-3 of p srx

Electron Tracking Compton Camera
30cm-cubic Gas Time Projection Chamber--- tracking of recoil electron --well-defined PSF based ARM & SPD
dE/dx + kinematical test using aScintillator Array for scattered g

ETCC for balloon Exp. (SMILE-II）

電子

1m

Focus image
Left CC
Right ETCC

Well-defined PSF in ETCC and leakage in CC(a)ETCC (662keV±10.7%)
60o

CC (662keV±10.7%)
60o

30o

3(c)

1232

130o(b)32
1137Cs(d)Source Area
Solid red lines :ETCC
Dotted blue lines :CC
Dotted brown :BG.

123

Case S/N ~1 : a peak density of CC increases by ~3 times due to the leakage
of background to the source position

4ETCCのPSF(15o)

CCのPSF(35o)
ETCC PSF 15o

CCCC
ARM 5o-> 2o
ETCC

ETCC PSF(15o) 実測値(b)

CC PSF(35o) 実測値

PSF

(c)

Tanimori et al., ApJ (2015), 810, 28

SPD 100o->10o

5Noise Reduction by Imaging Spec.
FoV ４sr（～60o Radius）PSF 5o FoV 0.02sr BG~1/150
Scattered gamma in Air

Objects

137Cs point

DWsource

PSF 15o

22Na (27 kBq, 511 keV)

8x10-5μSv/h

ETCC

5.5m(1/1000 of Environmental radiation)

Tanimori et al., ApJ (2015)

4psr

Point Spread Function ine- energies

Multiple scattering angle

E<80kev

PSF(7o) SPD 50o ARM 5o
PSF(5o) SPD 25o ARM 5o
PSF(1.2o) SPD 5o ARM 2o

E>80kev

 For good PSF of ~1o
3D-tracking with 1mm in Gas or
3D 1mm sampling in Solid State is inevitable !
Already GAS is possible !!!

Possibility of <1m CrabFor Next MeV Astronomy, significance ~10-13 erg cm-2 s-1
S: signal
q: PSF

Significan ce 
B𝐺 𝑑𝑜𝑚𝑖𝑛𝑎𝑡𝑒𝑑

2. Significance EA  SEA  S  BG  q 2EASq√(EA BG)

1. Effective Area ～200 cm2 Possible !

検出感度



2. BG. Cosmic MeV background（PSF, dE/dx, kinematical test) Possible !
=>PSF q＝ 1～2o inevitable !!

Gas electron tracking may be a unique solution
 “An Electron-Tracking Compton Telescope for a Survey of the Deep Universe by MeV gammarays” T.Tanimori et al. ApJ 810 (2015)
 ”Establishment of Imaging Spectroscopy of Nuclear Gamma-Rays based on Geometrical Optics”
T.Tanimori et al. Scientific Reports 7, (2017).
 “First On-Site True Gamma-Ray Imaging-Spectroscopy of Contamination near FukushimaPlant”, D.Tomono et al.Scientific Reports 7, (2017).

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Decontamination

1m線量

可搬型ETCC

検出面積 数mm2
PSF ~15oTomono et al., (2017),
Scientific Reports

Fluence (Real Imaging) Triggers
qSfy



EA  Cs  BGDf 2

EA  Cs~
EA  Cs

Noise area = (Df x Df
Df/Dq =10 Noise reduction -> 1/102~1/103.
 Very Low BG and Large Field of View (>4str)
 Wide band trigger in νFν (70keV ~>10MeV)
 Wide range of accumulation time 0.1-106s
little bias for any type of GRBs
insensitive for dilation factor
little Sensitive for Epeak and RedshiftxPosition Accuracy~20gammas <0.5oLuminosity Trigger
region

EA  Cs

GRB(z~20)

GRB(z~3)

νFν
Fluence Trigger
region10keV100keV

1MeV

EgammaShort GRB formation rate
D. Yonetoku, T. Nakamura, T. Sawano et al. 2014
Cumulative redshift distribution

22 SGRBS with known z

Absolute SGRB Rate (events/Mpc3/yr)
10-10
10-9
10-8
10-7

100試行MCによる誤差領域

Short GRB Formation Ratewith L > 1050 erg/sec

45 SGRBS of BATSE estimated― best estimation― 100 trials of MC
Redshift (1+z)

Rate of SGRBs with Luminosity > 1050 erg/s based on BATSE data

~ 0.02 events/year in (200 Mpc)311

ETCC sensitivity for short GRBs
Sensitivity of ETCC for SGRBs
Case 1; 25ph, 66σ
0.5 ph/cm2/s (1-1000 keV)
⇒1.3×10-7 erg/cm2/s, ~ 0.4o

satellite-ETCC (13σ, 5 ph)Case II 5 ph, 13σ⇒2.6×10-8 erg/cm2/s, ~ 0.9o
+ X-ray Telescope -> <0.1o
BATSE flux limit~ 1×10-6 erg/cm2/s
Fermi/GBM
Av. Epeak ~ 490 keV(Yonetoku et al. 2014)

ETCC 10 times better
Brightness fuction∝L-1
Sensitivity x10 ⇒ # Det. x10

0.02 x10 ~ 0.2 events/year within 200Mpc
In 5years Observation. ~1 coincidence event with GW is expected !
From Doctor thesis of T.Sawano
12Another Approach to GW
Kilo nova or micro nova-> Neutron Star merger
Dominant emission MeV gamma 1041-42erg/s
1-10days bright~10days 10-4 gammas /cm2s at 3Mpc kilo nova
Satellite-ETCC10days ~104 gammas detection
20Mpc ~300 gammas >300keV√BG ~100>3s

N-N GW ~103year within 200Mpc~1 year within 20Mpc
Most efficient method ??
Hotokezaka 2017

And Proof of R-process13

Fluence Trigger for long GRB(G. Ghirlanda et al. MNRAS 448, (2015))

1. Time dilation
Fluence trigger is NOT affected.
2. Redshift
Broad band SED (keV to 10 MeV)
little effect on fluence.
Photon flux trigger

Satellite-ETCC (T90: 10-100 sec)--> Fluence ~10-8 erg cm-2
(2-3 GRBs/year/str (z>10))+ wide FoV >4 str--> Several GRBs/year (z >10)200 GRBs/year (z > 5)
Energy band
50-300 keV --> 50 keV-10 MeV
more GRBs will be detected.
Fluence trigger~0.1[ph cm-2 s-1]

~10-8[erg cm-2]

2-3 GRBs[yr-1 str-1]
G. Ghirlanda et al.
MNRAS 448, (2015)

2-3 GRBs[yr-1 str-1]

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Ultra Long duration GRBs (POP-III)
D. Nakauchi et al. ApJ 759 (2012)z=9

Mass (solar )

EXIST

ETCC

M = 40 Msolar

EXIST

redshitfs

ETCC

M = 70z = 19Assumed Ep-Eiso relation (Amati) --> Ep~120 keV @z = 9

EXIST limit: 2.4x10-10 erg cm-2 s-1 (500 s)

Satellite-ETCC; S/√N >5s103s; S ~90g BG 200g -> 4x10-11 erg cm-2 s-1
105s; S ~800g BG 2x104 g -> 4x10-12 erg cm-2 s-1

Flux

Pop-III Flux <10-10 erg cm-2 s-1 (very faint)
But, Fluence ~10-5 erg cm-2(Intense)

POP-III

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Exploring GRB astronomy by Balloon-SMILE
1. SMILE-II+ one-day flight at Australia in March 2018
2. Next plan, SMILE-III Long-duration flight with larger ETCCs
Polar region 14-50 days (Tobs >106 sec)
40 cm-cubic ETCC x2 modules (Eff. Area ~80 cm2)

106 s --> ~3x10-11 erg cm-2 s-1 (+ FoV of 4 str) --> ~1 GRBs/day
In addition, Polarization Measurements
MDP ~ 6% for 10-6 erg cm-2 s-1 ( several GRBs/month)
Modulation Curve~ 20% for 10-7 erg cm-2 s-1 (~20 GRBs/month)

POP-III
SMILE-III

Satellite-ETCC

GRB detection inSMILE-III
Simulated by T.
Sawano0deg.

45deg.

90deg.

16

Primordial Black Holes in Solar System M M3~~ 1010 yr  15  10 g 315 10 g dE10g
20-1  ~ 100 MeV ~ 10 erg s dt M  M 215Primordial B.H. still surviving
would emit ~20MeV thermal M~ 1015 g , ~ 1020 erg/s

Density ~104 pc-3 (flat 分布で）104 pc-3 -> ~10 BH <Oort cloud (104AU)
Condensation Factor in Galactic halos x ~106＝＞ 100AU 球に~10BHs
Satellite-ETCC g線１０個 (1MeV)s-1 @1AU for 1020erg/s
ＢＨが106ｓの間同じ天球位置として、検出限界100g@106s
この場合、300ＡＵのＢＨまで観測可能 数10個のＢＨが見える。
さらに太陽系の増幅効果、ディスク（黄道面）分布、太陽近傍集中1桁以上の増加、さらにコメット軌道（数日、明るい）、

Biggest Explosion in Universe 1052-54erg

TMT?

JWSTz～>20

Larson&Bromm 02

GRBGalaxy & QSO

z~10

First Star& Galaxy
SKALong GRBs

Short GRBs

Neutron StarMerger

KAGRA

Summary
ETCC provides Imaging Spectroscopic Observation, andhence reveals the reliable way to reach 1 mCrab
sensitivity.
Clear imaging with well-defined PSF in sub-MeV gives atrue Imaging Trigger (Fluence Trigger) and provides achance to reach most distant GRBs of any type (Short,Long, and Ultra-long). + multi wave observations
Kilonova（３０Mpc) Supernova （１００Mpc） Answer for
Nucleosynthesis
来年 ３月に気球上がります。

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