Quest for the Origin of Cosmic Rays
with Gamma-Ray Observations
Hiroyasu Tajima
Institute for Space-Earth Environmental Research,
Nagoya University

G. Pérez, IAC, SMM

January 5–7, 2017
The 3rd International Symposium
on “Quest for the Origin of Particles and the Universe”
Nagoya University, Japan

Cosmic-Ray (CR) Accelerators✤ At least two CR accelerators may exist

RELATIVE PARTICLE FLUX (LOGARITHMIC UNITS)• Knee implies acceleration limit: Pmax ∝ B × (size of accelerator)• Supernova remnants are the leading candidate- Energetics
Scientific American 1998
- Acceleration mechanism
1 PARTICLEPER SQUARE❖ Extragalactic accelerator
METER PER SECOND• Milky way cannot hold cosmic rays
above P ≈ 1017 eV
1 PARTICLE• Cosmic rays above Ankle are
PER SQUAREMETER PER YEAR
considered to be extragalactic✤ Gamma ray is an excellent messenger
KNEE
to study cosmic-ray accelerators
1 PARTICLE❖ Neutral (not bent by magnetic field)
PER SQUARE❖ Produced by CRs interacting with
KILOMETERPER YEAR
interstellar matter• Electrons can also produce gamma rays
via Compton up-scattering or
Bremsstrahlung
1010 1012 1014 1016 1018 1020
Quest for the Origin of Cosmic Rays with Gamma-Ray Observations
KMI2017, JAN 5–7 2017, Nagoya University

JENNIFER C. CHRISTIANSEN❖ Galactic accelerator

2 /26

Gamma-ray Emission from Electrons/Hadrons✤ Electron origins❖ Synchrotron radiation❖ Compton up-scattering (Inverse Compton)❖ Bremsstrahlung✤ Hadron origins

log(Energy Flux) (E2•dN/dE)❖ π0 production and decay

parent population
∝E−p

UB/Uγ
∝E−p

Synchrotron
Emission∝E−(p+1)/2

Compton
Up-Scattering

π0 production
and decay

Bremsstrahlung

Radio

Infra-red

Quest for the Origin of Cosmic Rays with Gamma-Ray Observations
KMI2017, JAN 5–7 2017, Nagoya University

X-raysγ-rays log(Energy)
3 /26

Gamma-ray Instruments
Satellite based pairconversion
telescope
Experiments
Energy range

EGRET, Fermi

Air shower array
Milagro, HAWC

Atmospheric
Cherenkov
telescope
HESS, VERITAS,
MAGIC, CTA

0.02 – 300 GeV

1 – 100 TeV

0.1 – 100 TeV

Energy resolution

5 – 15%

~100%

~10%

Angular resolution

0.1 – 10 deg~1 deg~0.1 deg

Collection area

~1 m2

103 – 104 m2

105 – 106 m2

Field of view

2.4 sr2 sr

10-2 sr

Duty cycle

~95%

>90%

<10%

γ

e+

e–

Quest for the Origin of Cosmic Rays with Gamma-Ray Observations
KMI2017, JAN 5–7 2017, Nagoya University

4 /26

Pair–Conversion telescope✤ LAT (Large Area Telescope) on board Fermi Observatory✤ Satellite experiment to observe cosmic gamma rays
❖ Wide energy range: 20 MeV to >300 GeV❖ Large effective area: > 8000 cm2 (~6×EGRET)❖ Wide field of view: > 2.4 sr (~5×EGRET)❖ Total mass: 3000 kg❖ Size: ~1.5 m (W) × 0.6 m (H)γ❖ Total Power: 650 W

Si Tracker
70 m2, 228 µm pitch~0.9 million channels✤ Pair conversion❖ “Clear” signature

Large Area
Telescope (LAT)❖ Background rejection

Anti-coincidence Detector
Segmented scintillator tiles
99.97% efficiency
Gamma-ray
Burst
MonitorQuest for the Origin of Cosmic Rays with Gamma-Ray Observations
KMI2017, JAN 5–7 2017, Nagoya Universitye+e-

CsI Calorimeter8.4 radiation length
5 /26

Fermi Science Highlights

J. McEnery
5th Fermi Symposium
Quest for the Origin of Cosmic Rays with Gamma-Ray Observations
KMI2017, JAN 5–7 2017, Nagoya University

6 /26

Fermi Science Highlights
Figures produced by us

J. McEnery
5th Fermi Symposium
Quest for the Origin of Cosmic Rays with Gamma-Ray Observations
KMI2017, JAN 5–7 2017, Nagoya University

6 /26

Air Shower Array

About 10-20% of the energies can reach
HAWC altitude (4,100 m)
Shower direction can be
estimated from the relative
arrival time delays

HAWC/WIPAC
Quest for the Origin of Cosmic Rays with Gamma-Ray Observations
KMI2017, JAN 5–7 2017, Nagoya University

7 /26

Air Shower Array
Thomas Weisgarber,
TeVPA 2016θ ≈ 40°1.8 m

About 10-20% of the energies can reach
HAWC altitude (4,100 m)
Shower direction can be
estimated from the relative
arrival time delays

HAWC/WIPAC
Quest for the Origin of Cosmic Rays with Gamma-Ray Observations
KMI2017, JAN 5–7 2017, Nagoya University

7 /26

Imaging Atmospheric Cherenkov Telescope
Cherenkov Light
50 photons/m2 (5 pe/m2) at 1 TeV

Typical parameters
Energy range
50GeV ~ 10TeV
CR rejection power >99%
Angular resolution ~0.1 degrees
Energy resolution ~20%
Detection area
~105m2
Sensitivity ~1% Crab Flux (10-13 erg/cm2s)
Quest for the Origin of Cosmic Rays with Gamma-Ray Observations
KMI2017, JAN 5–7 2017, Nagoya University

8 /26

Imaging Atmospheric Cherenkov Telescope
Cherenkov Light
50 photons/m2 (5 pe/m2) at 1 TeV

Typical parameters
Energy range
50GeV ~ 10TeV
CR rejection power >99%
Angular resolution ~0.1 degrees
Energy resolution ~20%
Detection area
~105m2
Sensitivity ~1% Crab Flux (10-13 erg/cm2s)
Quest for the Origin of Cosmic Rays with Gamma-Ray Observations
KMI2017, JAN 5–7 2017, Nagoya University

8 /26

Imaging Atmospheric Cherenkov Telescope
Cherenkov Light
50 photons/m2 (5 pe/m2) at 1 TeV

Typical parameters
Energy range
50GeV ~ 10TeV
CR rejection power >99%
Angular resolution ~0.1 degrees
Energy resolution ~20%
Detection area
~105m2
Sensitivity ~1% Crab Flux (10-13 erg/cm2s)
Quest for the Origin of Cosmic Rays with Gamma-Ray Observations
KMI2017, JAN 5–7 2017, Nagoya University

8 /26

Imaging Atmospheric Cherenkov Telescope
Cherenkov Light
50 photons/m2 (5 pe/m2) at 1 TeV

Typical parameters
Energy range
50GeV ~ 10TeV
CR rejection power >99%
Angular resolution ~0.1 degrees
Energy resolution ~20%
Detection area
~105m2
Sensitivity ~1% Crab Flux (10-13 erg/cm2s)
Quest for the Origin of Cosmic Rays with Gamma-Ray Observations
KMI2017, JAN 5–7 2017, Nagoya University

8 /26

Imaging Atmospheric Cherenkov Telescope
Cherenkov Light
50 photons/m2 (5 pe/m2) at 1 TeV

Typical parameters
Energy range
50GeV ~ 10TeV
CR rejection power >99%
Angular resolution ~0.1 degrees
Energy resolution ~20%
Detection area
~105m2
Sensitivity ~1% Crab Flux (10-13 erg/cm2s)
Quest for the Origin of Cosmic Rays with Gamma-Ray Observations
KMI2017, JAN 5–7 2017, Nagoya University

8 /26

Imaging Atmospheric Cherenkov Telescope
Cherenkov Light
50 photons/m2 (5 pe/m2) at 1 TeV

Typical parameters
Energy range
50GeV ~ 10TeV
CR rejection power >99%
Angular resolution ~0.1 degrees
Energy resolution ~20%
Detection area
~105m2
Sensitivity ~1% Crab Flux (10-13 erg/cm2s)
Quest for the Origin of Cosmic Rays with Gamma-Ray Observations
KMI2017, JAN 5–7 2017, Nagoya University

8 /26

Imaging Atmospheric Cherenkov Telescope
Cherenkov Light
50 photons/m2 (5 pe/m2) at 1 TeV

Typical parameters
Energy range
50GeV ~ 10TeV
CR rejection power >99%
Angular resolution ~0.1 degrees
Energy resolution ~20%
Detection area
~105m2
Sensitivity ~1% Crab Flux (10-13 erg/cm2s)
Quest for the Origin of Cosmic Rays with Gamma-Ray Observations
KMI2017, JAN 5–7 2017, Nagoya University

8 /26

Imaging Atmospheric Cherenkov Telescope
Cherenkov Light
50 photons/m2 (5 pe/m2) at 1 TeV

Typical parameters
Energy range
50GeV ~ 10TeV
CR rejection power >99%
Angular resolution ~0.1 degrees
Energy resolution ~20%
Detection area
~105m2
Sensitivity ~1% Crab Flux (10-13 erg/cm2s)
Quest for the Origin of Cosmic Rays with Gamma-Ray Observations
KMI2017, JAN 5–7 2017, Nagoya University

8 /26

Performance Comparisons✤ Fermi, HAWC and IACTs are complimentary❖ Fermi and HAWC provide survey of unknown sources and long-term temporal monitoring❖ Fermi and IACTs provide good spectral information❖ IACTs provide better imaging and short variability measurements

2013APh....50...26A

Quest for the Origin of Cosmic Rays with Gamma-Ray Observations
KMI2017, JAN 5–7 2017, Nagoya University

9 /26

Particle Acceleration in SNR✤ Young shell-type supernova remnant: SN1006❖ Power law spectrum from rim is best described by synchrotron

emission by ultra-relativistic electrons❖ First evidence of particles accelerated to > 1014 eV

Koyama et. al
1995Natur.378..255K
Quest for the Origin of Cosmic Rays with Gamma-Ray Observations
KMI2017, JAN 5–7 2017, Nagoya University

10 /26

Particle Acceleration in SNR✤ Young shell-type supernova remnant: SN1006❖ Power law spectrum from rim is best described by synchrotron

emission by ultra-relativistic electrons❖ First evidence of particles accelerated to > 1014 eV

Radio
Koyama et. al
Optical
X-ray (Chandra)NASA, ESA, Zolt Levay (STScI)

Quest for the Origin of Cosmic Rays with Gamma-Ray Observations
KMI2017, JAN 5–7 2017, Nagoya University

1995Natur.378..255K

10 /26

TeV Gamma Ray from SNR✤ H.E.S.S. observation of TeV gamma rays from RX J1713.7-3946❖ Evidence for “particle” acceleration > 1014 eV❖ Morphological similarity with X-ray observation❖ Spectral feature can not conclusively distinguish leptonic or

hadronic origin of gamma rays
Aharonian et al. 2005
Aharonian et al. 2005

HESS/ASCATeV gamma-ray

Molecular clouds❖
Quest for the Origin of Cosmic Rays with Gamma-Ray Observations
KMI2017, JAN 5–7 2017, Nagoya University

11 /26

TeV Gamma Ray from SNR✤ H.E.S.S. observation of TeV gamma rays from RX J1713.7-3946❖ Evidence for “particle” acceleration > 1014 eV❖ Morphological similarity with X-ray observation❖ Spectral feature can not conclusively distinguish leptonic or

hadronic origin of gamma rays
Aharonian et al. 2005

HESS/ASCA

Aharonian et al. 2005
Fukui et al.
2012ApJ...746...82F

TeV gamma-ray

Molecular clouds❖
Quest for the Origin of Cosmic Rays with Gamma-Ray Observations
KMI2017, JAN 5–7 2017, Nagoya University

11 /26

RX J1713.7-3946 Spectra✤ Both models have issues describing Fermi and H.E.S.S. spectraat the same time
❖ Requires further investigations to distinguish hadronic or
leptonic nature of gamma-ray emissions
2011ApJ...734...28A

Electron origin

H.E.S.S.

Hadron origin

Fermi-LAT

Quest for the Origin of Cosmic Rays with Gamma-Ray Observations
KMI2017, JAN 5–7 2017, Nagoya University

12 /26

“Hard” Gamma-Ray Spectra✤ “Hard” gamma-ray can be explained by higher target density forhigher energy particles❖ Highly inhomogeneous molecular clouds interacting with SNR

TOWARD UNDERSTANDING THE YOU❖ Higher energy protons can penetrate into the cloud core wheretarget gas density is highwind bubble
primary shock

wind shell

ISM

synchrotron
radiation

eddy generation/
B amplification

short-time variabilityof X-rays
exploded starreflected shock

hadronic γ-rays
2012ApJ...744...71I
Quest for the Origin of Cosmic Rays with Gamma-Ray Observations
KMI2017, JAN 5–7 2017, Nagoya University

dense clump/core

shocked clump/core
13 /26

“Smoking gun” Signature of π0-decay γ-rays✤ Sub-GeV spectra of IC443/W44 agree well with π0-decay spectra✤ Other models cannot describe the spectrum very well
❖ Compton up-scattering• Energetically completely disfavored (×100 higher radiation fields)• Shape not consistent with Compton up-scattering❖ Best-fit Bremsstrahlung model shows less steep decline• Even with abrupt cutoff at 300 MeV in electron spectrum

Quest for the Origin of Cosmic Rays with Gamma-Ray Observations
KMI2017, JAN 5–7 2017, Nagoya University

14 /26

“Smoking gun” Signature of π0-decay γ-rays✤ Sub-GeV spectra of IC443/W44 agree well with π0-decay spectra✤ Other models cannot describe the spectrum very well
❖ Compton up-scattering• Energetically completely disfavored (×100 higher radiation fields)• Shape not consistent with Compton up-scattering❖ Best-fit Bremsstrahlung model shows less steep decline• Even with abrupt cutoff at 300 MeV in electron spectrum
IC 443W44
10-10

E2 dN/dE (erg cm-2 s-1)

-2

E2 dN/dE (erg cm s-1)

10-10

10-11

Best-fit broken power law
Fermi-LAT
AGILE (Giuliani et al. 2011)/0-decay
Bremsstrahlung
Bremsstrahlung with Break

10-12

8

10

9

10

10

10

10-11

Best-fit broken power law
Fermi-LAT
VERITAS (Acciari et al. 2009)
MAGIC (Albert et al. 2008)
AGILE (Tavani et al. 2010)/0-decay
Bremsstrahlung
Bremsstrahlung with Break

10-12

1011

1012

Energy (eV)Quest for the Origin of Cosmic Rays with Gamma-Ray Observations
KMI2017, JAN 5–7 2017, Nagoya University

8

10

9

10

10

10

Energy (eV)

1011
1012
Science, 339 (2013) 807

14 /26

Remaining Issues✤ We have not found SNRs which can accelerate CRs up to Kneeenergies (gamma-ray energy > 100 TeV): PeVatrons❖ Evolution with SNR age❖ Escape of CR from SNRs

✤ We need to find more multi-TeV gamma-ray sources
Stefan Funk

2012ApJ...749L..35U> 10,000 years~1,000 years
SNR W44
CO: contours

Fermi-LAT<1,000 years

Quest for the Origin of Cosmic Rays with Gamma-Ray Observations
KMI2017, JAN 5–7 2017, Nagoya University

MC complex is illuminatedby a “CR halo” around W44

15 /26

PeVatron Candidate✤ H.E.S.S. found a PeVatron candidate,

HESS J1641−463 within aboundary of SNR G338.5+0.1❖ Estimated age of 1.1 – 1.7 kyr, estimated distance of ~11 kpc❖ No X-ray counterpart found by Chandra/XMM-Newton❖ Fermi-LAT found both sources✤ Spectrum implies hadronic origin with Emax > 1 PeV
1509.08310v2

p-p collisions

10-11

IC off CMB photons

10-12

dNp/dE ∝ E−2.1

-13

-2 -1

10-15

TeV cm s

10

-1

10

-14

10-16
10-17

PSR J1640− 4631

dNe/dE ∝ E−3.14

-18

10

1FHL J1640.5− 4634
-19

10

Quest for the Origin of Cosmic Rays with Gamma-Ray Observations
KMI2017, JAN 5–7 2017, Nagoya University

Klein-Nishina
suppression

HESS J1641-463
Cutoff 100 TeV
Cutoff 200 TeV
Cutoff 1000 TeV
NoCutoff
HESS 1713.7-3946
1

10
TeV

HESS J1641-463
Cutoff=700 TeV
Cutoff=1000 TeV
NoCutoff
HESS 1713.7-3946
100

1

10
TeV

100

16 /26

Another PeVatron Candidate✤ H.E.S.S. found a PeVatron candidate in the Galactic center region❖ Diffuse gamma-ray emission correlate with interstellar matter• TeV electrons cannot propagate long distance❖ CR density shows 1/r dependence• Implies continuous injection from a source and propagation by diffusion❖ CR source can be Sgr A* (supermassive blackhole in GC) or SNR

G359.95−0.04• Both can explain total proton energy of 1.0 × 1049 erg✤ Spectrum implies hadronic origin with Emax > 3 PeV
adoi:10.1038/nature17147

b

Sgr A*Sgr A*✤
Quest for the Origin of Cosmic Rays with Gamma-Ray Observations
KMI2017, JAN 5–7 2017, Nagoya University

17 /26

Another PeVatron Candidate✤ H.E.S.S. found a PeVatron candidate in the Galactic center region❖ Diffuse gamma-ray emission correlate with interstellar matter• TeV electrons cannot propagate long distance❖ CR density shows 1/r dependence• Implies continuous injection from a source and propagation by diffusion❖ CR source can be Sgr A* (supermassive blackhole in GC) or SNR

G359.95−0.04• Both can explain total proton energy of 1.0 × 1049 erg
wCR (≥ 10 TeV) (10 -3 eV cm-3)✤ Spectrum implies hadronic origin with Emax > 3 PeV
adoi:10.1038/nature17147

30

b
20

10

1/r

Sgr A*

6.0 × local CR density

Sgr A*
1/r 2

2
0

✤
Quest for the Origin of Cosmic Rays with Gamma-Ray Observations
KMI2017, JAN 5–7 2017, Nagoya University

20

40

60

80

100

120

140
160
180
200
Projected distance (pc)

17 /26

Another PeVatron Candidate✤ H.E.S.S. found a PeVatron candidate in the Galactic center region❖ Diffuse gamma-ray emission correlate with interstellar matter• TeV electrons cannot propagate long distance❖ CR density shows 1/r dependence• Implies continuous injection from a source and propagation by diffusion❖ CR source can be Sgr A* (supermassive blackhole in GC) or SNR

G359.95−0.04• Both can explain total proton energy of 1.0 × 1049 erg
E2× Flux (TeV cm -2 s-1)

✤ Spectrum implies hadronic origin with Emax > 3 PeV
10

doi:10.1038/nature17147-10

dNp/dE ∝ E−2.4

a

b

10-11

Sgr A*Sgr A*

10-12
Diffuse emission (× 10)
Model (best fit): Diffuse emission
68% CL= 2.9 PeV

90% CL= 0.6 PeV

95% CL= 0.4 PeV

Model: Diffuse emission Ecut,pModel: Diffuse emission Ecut,p

10

-13

Model: Diffuse emission Ecut,pHESS J1745-290

✤
1

10

Energy (TeV)

Quest for the Origin of Cosmic Rays with Gamma-Ray Observations
KMI2017, JAN 5–7 2017, Nagoya University

17 /26HAWC View of Northern Sky✤ HAWC found many multi-TeV gamma-ray sources along Galactic

plane in the first year of operation with partial array

http://www.hawc-observatory.org

Quest for the Origin of Cosmic Rays with Gamma-Ray Observations
KMI2017, JAN 5–7 2017, Nagoya University

18 /26

Significance Map of Galactic Plane
Significance mapwith uniform diffuse gamma ray

Significance map for 11 seed sources

Residual

2016ApJ...817....3A
Quest for the Origin of Cosmic Rays with Gamma-Ray Observations
KMI2017, JAN 5–7 2017, Nagoya University

19 /26HAWC Galactic Source Candidatesb (deg)Flux(10−14 TeV/cm2/s)

Post-trial
significance

1HWC J1907+062

40.2±0.2 −0.7±0.2

22.0±4.6 @4 TeV

4.6σ

HESS

1HWC J1904+080

41.5±0.2

19.0±4.4 @4 TeV

3.9σ

—

Sourcel (deg)0.8±0.2

Counterpart—

38.5±0.4 −0.9±0.4

—

2.5σ

—

1HWC J1857+023

35.6±0.2 −0.2±0.2

18.0±3.0 @5 TeV

6.2σ

HESS, MAGIC

1HWC J1838–060

26.1±0.3

0.2±0.3

11.3±1.2 @7 TeV

6.1σ

HESS

1HWC J1844–031

29.3±0.2

0.2±0.2

11.8±2.4 @6 TeV

4.7σ

HESS

1HWC J1849–017

31.2±0.3 −0.3±0.3

9.1±2.2 @6 TeV

3.7σ

HESS

1HWC J1842–046

27.8±0.3

0.0±0.3

7.0±1.6 @7 TeV

3.4σ

HESS

1HWC J1836–090

23.1±0.3 −0.6±0.3

5.8±1.3 @8 TeV

3.2σ

HESS

1HWC J1836–074

24.6±0.3

0.0±0.3

6.9±1.4 @7 TeV

3.2σ

HESS

1HWC J1825–133

18.1±0.2 −0.3±0.2

7.3±1.4 @9 TeV

5.4σ

HESS
2016ApJ...817....3A

Quest for the Origin of Cosmic Rays with Gamma-Ray Observations
KMI2017, JAN 5–7 2017, Nagoya University

20 /26

Future Gamma-ray Observatory✤ Cherenkov Telescope Array (CTA)❖ Large number of telescopes• Large collection area (×~30)• Better angular resolution (0.03°)❖ Optimized telescope configuration• LST: ~23 m ϕ × 4, ~20 GeV – 200 GeV• MST: ~12 m ϕ × 20, ~100 GeV – 10 TeV• SST: ~4 m ϕ × 70, ~5 TeV – 300 TeV❖ ~1000 of TeV gamma-ray sources

LST
MST

SST

G. Pérez, IAC, SMM

LST

MST

❖

SST (1M)

SST (ASTRI)

Quest for the Origin of Cosmic Rays with Gamma-Ray Observations
KMI2017, JAN 5–7 2017, Nagoya University

SST (GCT)
21 /26

Expected CTA Performance✤ CTA will provide precise spectral measurements up to 100 TeV

E2× Flux (TeV cm -2 s-1)

✤ CTA will provide better imaging of TeV gamma-ray sources10

doi:10.1038/nature17147-10

dNp/dE ∝ E−2.4
10-11

H.E.S.S. sensitivity (×10)
10-12CTA sensitivity (×10)
Diffuse emission (× 10)
Model (best fit): Diffuse emission
68% CL= 2.9 PeV

90% CL= 0.6 PeV

95% CL= 0.4 PeV

Model: Diffuse emission Ecut,pModel: Diffuse emission Ecut,p

10

-13

Model: Diffuse emission Ecut,pHESS J1745-290

1
Quest for the Origin of Cosmic Rays with Gamma-Ray Observations
KMI2017, JAN 5–7 2017, Nagoya University

10

Energy (TeV)

22 /26

Expected CTA Performance✤ CTA will provide precise spectral measurements up to 100 TeV✤ CTA will provide better imaging of TeV gamma-ray sources

Quest for the Origin of Cosmic Rays with Gamma-Ray Observations
KMI2017, JAN 5–7 2017, Nagoya University

22 /26

Nagoya Involvements with CTA✤ Silicon photomultiplier (SiPM) camera for dual-mirror telescopes❖ SiPM: low cost, durable, high photon detection efficiency (GCT)❖ High-density front-end electronics (GCT, SCT)
❖ Camera software (GCT)✤ Schwarzschild-Couder (SC) optics is required toachieve short focal length (and small camera)❖ SC optics also realize large field of view

• Sparse telescope spacing(Larger collection area)

camera~4 m

Gamma-ray Cherenkov
Telescope (GCT)
5 – 300 TeV
AU, FR, DE, JP, NL, UK~10 m

cameraSchwarzschild-Couder
Telescop (SCT)
0.1 – 10 TeV
US, DE, IT, JP
CTA collaboration
Quest for the Origin of Cosmic Rays with Gamma-Ray Observations
KMI2017, JAN 5–7 2017, Nagoya University

23 /26

GCT Development Status✤ “First light” of GCT prototype achieved with cosmic-ray showers❖ Contributions from Nagoya group• Front-end electronics (Tajima)• Camera software (Okumura)
photo taken by Okumura

CTA collaboration
Quest for the Origin of Cosmic Rays with Gamma-Ray Observations
KMI2017, JAN 5–7 2017, Nagoya University

24 /26

GCT Development Status✤ “First light” of GCT prototype achieved with cosmic-ray showers❖ Contributions from Nagoya group• Front-end electronics (Tajima)• Camera software (Okumura)
photo taken by Okumura

CTA collaboration
Quest for the Origin of Cosmic Rays with Gamma-Ray Observations
KMI2017, JAN 5–7 2017, Nagoya University

24 /26

GCT Development Status✤ “First light” of GCT prototype achieved with cosmic-ray showers❖ Contributions from Nagoya group• Front-end electronics (Tajima)• Camera software (Okumura)
photo taken by Okumura

CTA collaboration
Quest for the Origin of Cosmic Rays with Gamma-Ray Observations
KMI2017, JAN 5–7 2017, Nagoya University

24 /26

SCT Development Status✤ Prototype is being constructed at Arizona❖ Test performance of SC optics and SiPM camera

CTA collaboration
Quest for the Origin of Cosmic Rays with Gamma-Ray Observations
KMI2017, JAN 5–7 2017, Nagoya University

25 /26

Summary✤ At least two origins are expected for cosmic rays
❖ Galactic origin may have acceleration limit at a few PeV (PeVatron)❖ Extragalactic origin may be dominant above ~1017 eV✤ Supernova remnants (SNRs) are the leading candidate for

Galactic cosmic rays
❖ Fermi-LAT provided the first conclusive evidence that hadrons areaccelerated in SNRs from the spectral features of W44 and IC 443✤ SNRs are not proven to be PeVatrons yet❖ H.E.S.S. found two PeVatron candidates, one my be an SNR,

the other may be a supermassive blackhole❖ HAWC is expected to find more PeVatron candidates in northern
sky with longer operations of the full array❖ CTA is expected to provide more insights into the nature of thosePeVatron candidates

Quest for the Origin of Cosmic Rays with Gamma-Ray Observations
KMI2017, JAN 5–7 2017, Nagoya University

26 /26

Supplemental Slides

Quest for the Origin of Cosmic Rays with Gamma-Ray Observations
KMI2017, JAN 5–7 2017, Nagoya University

27 /26

CTA Sites

CTA collaboration
Quest for the Origin of Cosmic Rays with Gamma-Ray Observations
KMI2017, JAN 5–7 2017, Nagoya University

28 /26

CTA Project Timeline

CTA collaboration (as of Oct, 2016)
Quest for the Origin of Cosmic Rays with Gamma-Ray Observations
KMI2017, JAN 5–7 2017, Nagoya University

29 /26

Latest Results on RX J1713.7-3946

1609.08671v1
Quest for the Origin of Cosmic Rays with Gamma-Ray Observations
KMI2017, JAN 5–7 2017, Nagoya University

30 /26