ICRR Seminar @ ICRR Kashiwa

June 18, 2019

Current status and future prospects ofKAGRA gravitational wave telescope
Yuta Michimura
Department of Physics, University of TokyoSelf Introduction• Yuta Michimura (道村 唯太)• Interferometric gravitational wave telescope- KAGRA(Interferometer design and controls)- DECIGO• Test of fundamental physics
with laser interferometry- Lorentz invariance- Macroscopic quantum
mechanics- Axion searchetc…
2

Outline• Introduction- Gravitational waves- Interferometric detection- Observing runs

• Status of KAGRA- Project overview- Installation and test runs

• Future Prospects- KAGRA upgrade plans- Next generation• Summary3

Gravity in General Relativity• space-time bends with presence of mass
• bending affects motion of objects → gravity
T. Pyle/Caltech/MIT/LIGO Lab

4

Gravitational Waves• ripples in space-time created by motion of objects

5Characteristics of GWs• propagates at the speed of light• quadrupole radiation (+ mode and x mode)• high transmissivity ↔ very weak interaction• large mass and large
acceleration creates large GW• amplitude of GWfraction oflength change

6Sources of GWs

Binary neutron stars

Binary black holes
Pulsars

Supernovae

7

Laser Interferometric GW Detector• measure differential arm length change
Top view

Laser source

Beamsplitter

Photo-diodeSuspended mirror

Constant
Interference power when
no GW 8

Laser Interferometric GW Detector• measure differential arm length change
Top view

Laser source

Beamsplitter

Photo-diodeSuspended mirror

PowerInterference changes
with GW 9

Amplitude of GW is Tiny
• for example, h ~ 10-21

10-18 m for 1 km arm

1 km

Laser
sourceSize of hydrogen atom: 10-11 m
Size of proton: 10-15 m

1 km 吊るされた鏡
半透明鏡

Photo-diode

光の干渉
10

Global Network of GW Telescopes
Advanced LIGO
(operation)
GEO-HF(operation)
Advanced LIGOAdvanced Virgo(operation)

KAGRA(construction)

LIGO-India (approved)

11

Observation Scenario

Living Reviews in Relativity 21, 3 (2018); updated version available from12
https://git.ligo.org/publications/detectors/obs-scenarios-2018/blob/master/Figures/ObsScen_fig2_v12.pdf

Observation Scenario

3 BBHs

7 BBHs
1 BNS

14 publicalerts so far

Today

Living Reviews in Relativity 21, 3 (2018); updated version available from13
https://git.ligo.org/publications/detectors/obs-scenarios-2018/blob/master/Figures/ObsScen_fig2_v12.pdf

Solved and Unsolved Mysteries• Binary black holes- Origin of massive black holes?
- Intermediate mass black holes?
- Quasi-normal modes not yet• Binary neutron stars- coincidence with short gamma-ray bursts(but too faint; why?)- speed of gravitational waves measured- do all heavy elements come from BNS mergers?
- Remnant?
- Equation of state?
- Hubble constant tension• Other sources not detected yet- NS-BH, Supernovae, Pulsars, Primordial gravitational
14
waves……

What’s Next?
• More sensitive, multiple detectors- Better source localization with multiple detectors
Better multi-messenger observations- Polarization resolvable with multiple detectors
Better inclination angle estimation
Better Hubble constant measurement
Non-GR polarization search- Twofold sensitivity improvement gives
x8 event rate
x1/2 parameter estimation error• Next to join observation: KAGRA
15

KAGRA Project• Underground cryogenic interferometer in Japan• Funded in 2010
• 97 institutes, 460 collaborators (162 authors)
as of Sept 201816

KAGRA Site
• Located inside Mt. Ikenoyama

CLIO

KamLAND
Super-Kamiokande

OfficeControl room

KAGRA Tunnelentrance
17

KAGRA Site
• Located inside Mt. Ikenoyama

©NAOJ

18

Interferometer Configuration• RSE interferometer

ETMY• Cryogenic sapphire
test masses IMC
PRM
Laser

cryogenicsapphire(20 K)

3 km

Resonant Sideband Extraction

PR2

ITMY

IFI

ITMX

(140 W, 1064 nm)

ETMXBS

PR3SR2SR3SRMOFIΦ22 cm x t 15 cm
22.8 kg

OMC19Design Sensitivity• Binary neutron star (BNS) range 153 Mpc

Quantum20

KAGRA Timeline
2014

Tunnel excavation done

2015

Inauguration of initial-phase facility
First test run at room temp. (iKAGRA)

2016

KAGRA Collaboration, PTEP 2018, 013F01 (2018)

2017
2018

2019

First cryogenic test run (Phase 1)
KAGRA Collaboration, arXiv:1901.03569

Expect to join observing run O32020
21

Observation Scenario

iKAGRA(room temp.)
O3bKAGRA Phase 1(cryogenic)
Updated version of Living Reviews in Relativity 21, 3 (2018); available from22
https://git.ligo.org/publications/detectors/obs-scenarios-2018/blob/master/Figures/ObsScen_fig2_v12.pdf

Target Sensitivity for O3• Aims for 8-25 Mpc in binary neutron star range
KAGRA
target for
O3

KAGRA design
23Comparison with LIGO/Virgo• Aims for 8-25 Mpc in binary neutron star range
KAGRA
target for
O3
AdV O3
Hanford O3
Livingston O3

aLIGO
designAdVKAGRA design design24

If KAGRA Joins O3• Improves sky coverage, network duty factor, source
parameter estimation• Some parameter degeneracy can be resolved withfour detectors (e.g. polarization)
BNS sky localization
improves by ~15-30 %if KAGRA is 25 Mpc

JGW-T1910330
Calculation
by S. Haino(L: 120 Mpc, V: 60 Mpc, K: 15 Mpc)

25

Test of GR with CBC Polarization• Fourth detector necessary to distinguish four
H. Takeda+, PRD 98, 022008 (2018)
polarizations• Number of detectors matters!
error reduces to < 1 with KAGRABNS w/ K
BBH10 w/ K

BNS HLV
BBH10 HLV

Error in vector-x mode amplitude
26

Recent News from KAGRAETMYIMCPRM
Laser

68 K3 km

• Almost everything installedby May 2019

PR2

ITMY 27 K29 KIFI• X-arm completed
PR3by January 2019
• Y-arm locked in April 2019
SR3
• Y-arm and central part
commissioning on-going• First Engineering Run withX-arm done on June 8, 2019

ITMX

39 K

ETMX

BS
SR2

SRM

Temperatures
as of June 12(ITMY/ETMY
once reached22K/24K)

OFIOMC

27

Observation Scenario

iKAGRA(room temp.)
O3
bKAGRA Phase 1(cryogenic)

UpgradeUpdated version of Living Reviews in Relativity 21, 3 (2018); available from28
https://git.ligo.org/publications/detectors/obs-scenarios-2018/blob/master/Figures/ObsScen_fig2_v12.pdf

Advanced LIGO Upgrade: A+• Reaches 325 Mpc with coating improvement andfrequency dependent squeezing

4 km arm
40 kg mirror
Fused silica

Livingston
O3Hanford
O3aLIGOA+

Budget approved
NSF $20.4M
UKRI £10.7M+ Australia

29

Advanced Virgo Upgrade: AdV+
• Reaches 300 Mpc with frequency dependent squeezing,
Newtonian noise cancellation, larger mirror

AdVO3

3 km arm
42 kg mirror
Fused silica

AdV

AdV+Phase 130

How about KAGRA?
• Upgrade study formally started in December 2018

heat
extraction

Quantum

31

How about KAGRA?
• Different investigation necessary due to cryogenic

Black holes

Neutron stars
heat
extraction

Lower power

Quantum
Higher power
Squeezing
Coating improvement
Larger mirror

32

Sensitivity Optimization• Simultaneous tuning of multiple interferometerparameters necessary• Developed a code to optimize the sensitivity withParticle Swarm Optimization

Y. Michimura+,
PRD 97, 122003 (2018)33

Possible Near Term Upgrade Plans• Based on technical feasibility, facility and budget
constraints (~5億円)

LF(BBH100Optimized)
40 kg mirror(BNS optimized)
Y. Michimura+,
arXiv:1906.02866

Frequency
dependentsqueezing(BNSoptimized)

HF(BNS skylocalizationoptimized) 34

Possible Longer Term Upgrade• Reaches BNS range of 300 Mpc by combining
technologies (~20億円?)

NOTE:
No coating
improvements
assumed100 kg, 340 W, 30 m filter cavity (5 dB SQZ)
Y. Michimura+,
arXiv:1906.02866

35

Possible Longer Term Upgrade• Comparable to A+ (325 Mpc) and AdV+ (300 Mpc)

AdV+
KAGRA+?
Y. Michimura+,
arXiv:1906.02866

A+36

Horizon Distance Comparison• O(102) events/year with designed sensitivity (~2021)

z=10aLIGO
z=1
KAGRAAdV

z=0.1

Optimal direction and polarization
SNR threshold 837

Horizon Distance Comparison• O(103) events/year with upgrades (~2024)

A+

AdV+

z=10

KAGRA+?
LF

z=1
40 kg
FDSQZ
HF z=0.1
Optimal direction and polarization
SNR threshold 838

Effective Progression of Upgrades?
• Low frequency is uncertain since many low
frequency excess noises exist• 40 kg mirror would be feasible but even larger
mirror is required for longer term
• Higher power laser and frequency dependent
squeezing are attractive in terms of feasibility• HF plan has better sensitivity than A+ and AdV+ athigh frequencies• Higher power laser → Squeezing → Frequency
dependent squeezing → Larger mirror
might be an effective progression
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Future Planning Committee• Formulated inside KAGRA Collaboration inDecember 2018
Sadakazu Haino (chair)
Chunglee Kim
Kentaro Komori
Matteo Leonardi
Yuta Michimura
Atsushi Nisizawa
Kentaro Somiya• White paper on KAGRA
upgrade work in progress(to be finalized by August 2019)- Available technology survey- Science case study

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Next Generation Detectors• Laser interferometric detector with 10-40 km arms
• Places not decided yet?

?

Einstein Telescope
Cosmic Explorer41

Next Generation Detectors• Einstein Telescope- 10 km、200 kg silicon mirror, underground
10 K and room temperature interferometers- Two candidate locations (decide by 2022)
Sardinia, Italy
Bergium-Germany-Netherlands border- Final design by 2023
- Anticipate to start installation from 2032
• Cosmic Explorer
40 km, 320 kg silicon mirror, 120 K• KAGRA is pioneering cryogenic and underground42

Sensitivity of Next Generations• An order of magnitude improvement

VoyagerETCE43

Horizon Distance• O(105) events/year with next generation detectors(~2035)z=10z=1
z=0.1

Optimal direction and polarization
SNR threshold 844

Summary• KAGRA is an underground cryogenic GW detector
pioneering next generation detectors• First observing run with LIGO and Virgo expectedlate 2019• KAGRA joining the observation improves sky
coverage, network duty factor, source parameterestimation• KAGRA upgrade study on-going, aiming for theupgrade by ~2024• Twofold sensitivity improvement is feasible for
KAGRA
45

Additional Slides46

2G/2G+ Parameter Comparison
KAGRA

AdVirgoaLIGO

A+Voyager

Arm length [km]33444Mirror mass [kg]

2342

40

80

200

Mirror material

Sapphire

SilicaSilicaSilicaSiliconMirror temp [K]

22295

295

295

123

Sus fiber

35cm Sap.

70cm SiO260cm SiO260cm SiO260cm Si

Fiber type

Fiber

Fiber

Fiber

Fiber

RibbonInput power [W]67125125125

140

Arm power [kW]340700

710

1150

3000

Wavelength [nm]10641064

1064

1064

2000

Beam size [cm]3.5 / 3.5

4.9 / 5.8

5.5 / 6.2

5.5 / 6.2

5.8 / 6.2

00068

none

none

none

16300

SQZ factor
F. C. length [m]LIGO parameters from LIGO-T1600119, AdVirgo parameters from JPCS 610, 01201 (2015)

47

KAGRA Detailed Parameters
•••

•
•

K. Komori et al., JGW-T1707038

Optical parameters- Mirror transmission: 0.4 % for ITM, 10 % for PRM, 15.36 % for SRM- Power at BS: 674 W- Detune phase: 3.5 deg (DRSE case)- Homodyne phase: 135.1 deg (DRSE case)
Sapphire mirror parameters- TM size: 220 mm dia., 150 mm thick- TM mass: 22.8 kg- TM temperature: 22 K
- Beam radius at ITM: 3.5 cm- Beam radius at ETM: 3.5 cm- Q of mirror substrate: 1e8- Coating: tantala/silica- Coating loss angle: 3e-4 for silica, 5e-4 for tantala- Number of layers: 22 for ITM, 40 for ETM- Coating absorption: 0.5 ppm- Substrate absorption: 50 ppm/cm
Suspension parameters- TM-IM fiber: 35 cm long, 1.6 mm dia.
- IM temperature: 16 K- Heat extraction: 5800 W/m/K at 20 K
- Loss angle: 5e-6/2e-7/7e-7 for CuBe fiber/sapphire fiber/sapphire blade
Inspiral range calculation- SNR=8, fmin=10 Hz, sky average constant 0.442478
Seismic noise curve includes vertical coupling, vibration from48
heatlinks and Newtonian noise from surface and bulk

KAGRA Cryopayload
Figure by T. Ushiba and A. Hagiwara

Platform(SUS, 65 kg)

3 CuBe blade springs

Marionette(SUS, 22.5 kg)

MN suspended by 1 Maraging steel fiber(35 cm long, 2-7mm dia.)
MRM suspended by 3 CuBe fibers
Heat link attached to MNIntermediate Mass
(SUS, 20.1 kg,16 K)

IM suspended by 4 CuBe fibers(24 cm long, 0.6 mm dia)
IRM suspended by 4 CuBe fibers
4 sapphire blades

Test Mass(Sapphire, 23 kg,22 K)

TM suspended by 4 sapphire fibers(35 cm long, 1.6 mm dia.)
RM suspended by 4 CuBe fibers
49

KAGRA Cryostat Schematic50

KAGRA Suspensions

51

KAGRA Interferometer

52

Possible
KAGRA
UpgradePlans

Y. Michimura+,
PRD 97, 122003 (2018);
JGW-T1809537

53Y. Michimura+,
PRD 97, 122003 (2018);
JGW-T1809537

Possible
KAGRA
UpgradePlans

54