LIGOʼs first detection of gravitational waves
and the development of KAGRA
KMI2017
Jan. 2017
Tokyo Institute of Technology
Kentaro Somiya

Self Introduction• Applied Physics (U Tokyo)• NAOJ 2000-04• Albert-Einstein Institute2005-07• Caltech 2008-2009• WIAS 2010
• Tokyo Tech 2011~

GravitySpacetime

Blackhole
Gravitational waveEarth

1916 Einstein

8GG  4 Tc1969 Weber1974 Hulse & Taylor(1993 Nobel Prize)70ʼs: Interferometric GW detector

1994 TAMA construction
1999 TAMA observation

2002 LIGO (US)2005 GEO (GE/GB)
2007 Virgo (IT/FR)
Observations started2010 Internal news of first GW?!

The 1G detectors were able to see GW
events of up to 70M lightyears distant,but found no real GW signal.

Decision to upgrade the detectors

Sensitivity of the 1G detectors

Virgo in Europe

LIGO in the US

Strain of 10-23(~10-19m/rtHz)

Sensitivities are limited by seismic noise,
thermal noise, and laser quantum noise.

Upgrade to 2G
LIGO

LIGO
Virgo
GEO

Virgo
LIGO

upgradeGEO

Advanced LIGOAdvanced Virgo
GEO-HF

TAMA

KAGRA

Big news on Feb 12th 2016Live streams in US and in Europe
0:30AM: Virgo announced the first detection
0:32AM: NSF person gave a speech in the US
0:35AM: LIGO announced the first detection
1:00AM: LIGO papers were published1:30AM: Prof Kajita (KAGRA PI) commented in web

Big news on Feb 12th 201636 and 29 Ms BHs merged to make a 62 Ms BH and
its inspiral, merger, ringdown signals were observed.

More details about this PRL• Waveform matched to a numerical relativity template• The same waveform was observed by 2 LIGOdetectors that are 3000km apart (with 6ms delay)• The distance to the BH is ca 1.3B lightyears• The Signal-to-noise ratio was 24 and the False-alarm
rate was calculated to be less than 1 in 200,000 yrs

LIGO
4 km
+ 2 km

4 km

Initial LIGO sensitivity ('02-'07)• Current members: 1006 (83 institutes)• Total budget: ca 120B JPY

Advanced LIGO sensitivity in ʻ15
From Initial LIGO,
x3~4 improvement at 100Hzx50 improvement at 50Hz

Observation range for
Neutron star binaries
is 0.2B lightyears

below 20Hz ⇒ Control noise
20~100Hz⇒ Mystery noise
above 100Hz ⇒ Quantum noiseData analysis

MergerInspiral

Ringdown
Whitening

Inspiral: 35-150Hz
Ringdown: 250Hz

Significance

LIGO continued the observation for 2 weeks after
the discovery to calculate the significance of thisevent compared with signal-like noises⇒ The difference is larger than 5σ

Second GW on Dec 26th 2015

14Ms and 7.5Ms BHs
merged to become
a 20Ms BH.

Second GW on Dec 26th 2015

Signal-to-noise ratio was not as high as the firstone but the significance was high for its longobservation time.

Engineering run and observation run• GW150914 was found during the engineering run• The result for the first 2 weeks was published inFebruary (the rest was published in June)• Observation was extended for a few days and thesecond GW was found in the extended period• The second observation run started Nov 2016.

KAGRA
Seismic isolation
systemLocation: Kamioka, Gifu

Cryogenic
Sapphiremirror

3km arms
180W
LASER

Signalrecycling• Underground facility + Cryogenic mirrors• To start the cryogenic operation in 2018
• Observation rage for NS binaries will be 0.5B LY

Cryogenic system• System in a radiation shield• Upper mass cooled via 6N Al heat link
• Sapphire test mass cooled in 23K via
Sapphire suspension fiberUnderground facility

2e-9m/rtHz@1Hz• Low seismic noise• Low gravity gradient noise• Low control noise due to low RMS motion

Inside the mineElectric car

electricscooterbicycle

Nov 2012
Tunnel excavation

Dec 2012
Cryostat manufacture(Toshiba factory)

View at the central area

Dec 2012

Jul 2014

Installation workin 2015-16
Most items were not yet
installed or temporarily
installed in 2016.

△△X△X△△ XXXXX△

But, facility, digital control
system, and infrastructure
were installed by 2016.

KAGRA test operation in 2016
300K

0.2W

20K

180W

at the test run

final configuration• 2 x 2week operation in 3/25-4/25• Test the integrated system– control system– commissioning– observation shift• World first operation of a km
scale underground GW detector

KAGRA schedule
2017: Installation of cryogenic suspensions
2018: Operation of a cryogenic interferometer
2019: Integration of optical resonators
2019~20: Commissioning and observation

Summary• Discovery of GW in 2015
• GW astronomy is about to begin• KAGRA is under development for
the first observation in 2019~20

KAGRA-Chan

Future projects
Space detectors(LISA, DECIGO)

3G detectors(Einstein Telescope,Cosmic Explorer)