VHE Gamma-Ray Astronomy andThe CTA Project
Masahiro Teshima
Institute for Cosmic Ray Research, The University of Tokyo, Japan
Max Planck Institute for Physics, Munich, Germany

La Palma, SpainParanal, Chile

History of VHE gamma-ray astronomy
Imaging Atmospheric Cherenkov Telescopeq The first idea of IACT from Michel Hillas in 1985 at ICRC in San Diego, USA
q Dr. Trever Weeks demonstrated the power of IACT with the Whipple telescope.
VHE gamma rays from the Crab Nebula is discovered in 1989 (1G)q è HESS, MAGIC and VERITAS (2G)q è CTA (3G)

The observation of the first extragalactic source Mrk421
M. Punch et al., Nature 1921

Canary Island, La Palma and ORM,
Observatory Roque de los Muchachos

TeV Gamma Rays
è EM shower
è Cherenkov LightHeight(km)Refractive Indexof Atmospheren = 1.000292
Light velocitycʼ = c/n= 0.9997 c

Top view of particle tracks

Particle velocityv~cAirplane
Cherenkov light
Footprint
Mt. Fuji~250m

Imaging Cherenkov
Telescopes

50photons/m2 at 1TeV

T1

T２

E le ctromagn etic cascade# of Photons:

T３n Energy range
n CR Rejectionn Angular Res.
n Energy Res.
n Effective Arean Sensitivity

T４100GeV ~ 100TeV~99.5%~0.06 degrees~15%~105m2~0.6% Crab Flux
(10-13 erg/cm2s)

In 2017 Dec

High Resolution Camera
調整後

Regular observation since 2020 Jan

May 2019, first images of cosmic rays

Science of CTA is very wide
SNRs, PWNe, AGNs, GRBs, Dark Matter

Cosmic Ray Origin

Super Massive
Black Holesn Origin of Cosmic Rays (Big accelerators)
n Black Hole and S.M.B.H.
n Dark Matter Search

Dark Matter Search (Discovery)

Extragalactic Sources

Active Galactic Nuclei

Gamma Ray Bursts

Galactic Sources> 220 high energy sources are discovered.
CTA will observe more than 1000 sources.

Super Nova Remnants

Binaries

9Alpha Configuration is decided withthe financial constraints
Roque de los Muchachos Observatory
La Palma, Spain

Paranal, Chile

Telescope Designx4

LST x 4MST x 23x7
SST x 37

Telescope Types
OpticsFoV and Camera

SSTMST

LST

Schwarzschild-Couder

Davies-Cotton

Parabolic (Isochronous)

7.5 deg PMT

4.3 deg PMT

10.5 deg

SiPM

Mirror Diameter

4.3m

11.5m

23m

Energy Range

3 TeV - 200 TeV100GeV - 10TeV

20GeV – 2000GeV

Galactic Sources
Nearby AGNs (z<0.5)
Dark Matter

Transient Sources
AGNs(z<2), GRBs(z <4)
Dark Matter

Science Targets

Galactic Sources
PeVatron (UHE CR)

10 times better sensitivity

Wide Energy coverage 20GeV~200TeV

100 hrs

GRBs
AGNs

GRBs
distant AGNsn CTA array has a 10 times better sensitivity than HESS, MAGIC, and VERITASn CTA covers wide energy range from 20GeV to 200TeV (4 orders of magnitude)n LSTs will offer

n Distant AGNs up to z = 2 and GRBs up to z = 4 are observable with LSTs
n X10000 sensitivity for GRBs and AGN flares than Fermin The fast rotation (20 sec) offers the observation of GRBs even in prompt phase

CTA: Ultimate Instruments
for HE and VHE gammas

Courtesy of T.Takahashi

Gamma Ray Horizon

20GeV Low Threshold Energy è z~4Fermi

LST@45o Eth 40GeV
LST@25o Eth 20GeV

Simulated AGN Flares
Template: the 2006 flare of PKS2155-304

Low Threshold Energy è High Precision Light curve

q Light curve can be examined, a few minutes scale structure è a few 10s of seconds
q Particle acceleration mechanism, Cooling process
q Light curve vs. Energy dependence è Q.G. Energy scale > Planck Mass scale

GRBs: Newly Born Black Holes

Simulated light curve (template: GRB080916C)

Interaction probability

Complementarity of different approaches
Direct, Indirect, and Collider Experiment

Xenon 1ton

(Underground exp.)

LHCCTA(Gamma Rays)(Accelerator)

LUX Xenon detector

Large Hadron Collider

Mass of DM
n Explore Dark Matter in the Galactic Center andDwarf Sph. Galaxies
n CTA has the best sensitivity above 700GeVDark Matter Search
Sensitive Mχ:200GeV - 10TeV

Particle Physics

Astrophysics

Canonical-σ

Gamma rays from Annihilation produce the bumparound 1/10 -1/20 Mχ è 20GeV-1TeV gamma

CTA gives the stringent upper limit.
Stefan Funk 2015

Commissioning of LST1
scientific observations

LST collaboration•LST is a large part of CTA•World-wide effort•Costbook value: 15MEuro/tel.
(incl. FTE)

numbers are growing

Daniel Mazin

A.meeting,
Tutone: Operation
CTA STAC
FebruarySpecialist23, 2023

3

LST1 construction andInauguration (Oct.2018)

LST Feature, FAST Rotation <20 seconds :for the fast follow-up GRB observations
調整後ST1 Commissioning

LST1 commissioning

500hrs of Scientific Observation
h taken since Jan 2020from Ruben

(change to backup slide when uploading to indico)5

Crab Nebula and Pulsar
Crab Nebula spectrum

Preliminary• 34.2 hours of data
• Systematic errors: gray points
correspond to the effect of +1%
background• Consistent with MAGIC and Fermi-LAT
Crab pulsar• Significant detection down to few tens of GeV• Data from Nov 2020 - Mar 2022

Preliminary
P1P2Index 1.83±0.021.97±0.02

Preliminary

3.16±0.06

Transition between FermiLAT and LST-1 is smooth
Smooth broken power law fit

3.96±0.12

Telescope Performance: Geminga
E >15GeV
VERY PRELIMINARY• P2: 8.9σ after 14 hours. Geminga has a very soft spectrum. The LST-1 result confirms anexcellent performance in the 15-30 GeV regime, one of the main scientific drivers of LST• Compared with MAGIC: 6.3σ for 80 hours for P2 (https://www.aanda.org/articles/aa/full_html/2020/11/aa39131-20/aa39131-20.html)

Detection of Nova RS Ophiuchi• First detected recurrent nova in VHE gamma rays
by 2021 outburst (H.E.S.S. and MAGIC)• LST-1 took part in the first VHE gamma-ray
detection with >~6σ in each night• Consistent SEDs between LST-1, MAGIC, H.E.S.S.

Nice connection
between LST-1
and Fermi-LAT

6

AGN observation with LST1
during 2020-2021Q1

q Nearby AGNs, Mrk501, Mrk421, 1ES 1959+650, BL Lac
q Distant AGNs, 1ES0647+250, PG1553+113

Z=0.034(460 Mly）
Z=0.048 (650 Mly）

BL Lac
Z=0.069 (940Mly)

https://www.dropbox.com/s/nwgq6mst06hawgb/%E3%82%B9%E3%82%AF%E3%83%AA%E3%8
3%BC%E3%83%B3%E3%82%B7%E3%83%A7%E3%83%83%E3%83%88%202021-0804%2021.51.18.png?dl=0

Z=0.5 (5.1 Gly）

New source Z 〜0.45 (4.7 Gly)
Z=0.031（430 Mly）

30

BL Lac Flare observed with LST1
by Dr. Seiya Nozaki

Big flare is observed in the night of 8 August 2022

SED measured down to 20GeV

Intranight Variability

5mins bin

Expand the Gamma Ray Horizon
up to z=4Fermi

LST@45o Eth 40GeV
LST@25o Eth 20GeVMAGIC Highlight,

Gamma Ray Burst GRB190114C (z=0.42)
Historical achievement

q First Detection of the GRB from ground.
q ~100 Crab flux in the first minutes.
q TeV bump has a similar energetics
with KeV-GeV bump

MAGIC Highlights

Other GRB observations with MAGICGRB 160821B
Short GRB under moon
E > 600GeV
Z = 0.162
3.1 σ (PostTrial)
Published in APJ 2021

GRB 201015A

GRB 201216C

Z = 0.426
3.5 σ (PostTrial)
Published, ICRC 2021̲797
Y. Suda et al.

Z = 1.106σ (PostTrial)
Published, ICRC 2021̲788
S. Fukami et al.

Long GRB in Dark

Long GRB in Dark

CTA LSTs will observe HighRedshift GRBs
CTA LST will observe GRBs and AGNs
during the structure formation periodof the UniverseFermi

LST@45o Eth 40GeV
LST@25o Eth 20GeV

Multi Messenger Astronomy
IC170922A / TXS 0506+056
Ice Cube Observation (~300TeV)

Fermi LAT(>100 MeV)

Lepto-Hadronic Scenario
MAGIC(>100GeV)GTC Observation z = 0.3365
S. Paiano et. al 2018

CTA North Phase I Installation Plan
LST1-4 location
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LST Critical Design Review, Munich, Oct 15-17, 2019/'6'1A

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LST2-4 status

LST2

D. Mazin, LST Project ManagerLST3LST4LST Critical Design Review, Munich, Oct 15-17, 2019

Multi-messenger andMulti-wavelength Astrophysics
Wave
AstroPhysics

ASTRO-PHYSICSASTRO-PARTICLE PHYSICS

Gamma Ray Bursts, Black holes,
Neutron Stars, Space and Time

Cosmic Ray Physics
High Energy Astrophysics

Particle Physics

PARTICLE PHYSICS
Dark Matter, Neutrino
Energy FrontierSummary• CTA is a big and ambitious project• LSTs play an important role in the Multi-Messenger
astronomy in the next decades• LST2-4 construction started in the winter 2022

• CTA South (SSTs, MSTs, and LST5-6) construction
will start in 2024
• CTA and current IACT will study• Cosmic Ray Origin• Evolution of Black Holes and Extreme environment
around Black Holes and neutron stars• Explore the Dark Matter in the Galactic Center and halo

Thank you very much