University	  of	  Tokyo,	  Institute	  for	  Cosmic	  Ray	  Research

Keiko	  Kokeyama
ICEHAP	  Seminar	   @	  Chiba	  UniversityJanuary	  26th,	  2017

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0My	  Profile
Keiko	  Kokeyama• Originally	  from	  Kobe,	  Kansai• Gravitational	   Wave	  Detection• Working	  for	  KAGRA	  Project• PhD	  in	  Ochanomizu University• Worked	  in	  LIGO	  Livingston,	  etc.

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Contents• Gravitational	   Wave	  (GW)	  Detection• About	  the	  Interferometric Detectors• Japanese	  Project,	  KAGRA• Future	  Prospects• (If	  we	  have	  time)	  Additional	  Stories

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Contents• Gravitational	   Wave	  (GW)	  Detection• About	  the	  Interferometric Detectors• Japanese	  Project,	  KAGRA• Future	  Prospects• (If	  we	  have	  time)	  Additional	  Stories

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LIGO	  Detected	  Gravitational	  Waves!

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4Nobel	  Prize!?
They	  already	  won...
• Special	  Breakthrough	  Prize	  in	  Fundamental	  Physics	  (Drever,	  Thorne,	  Weiss	  and	  the	  LIGO	  discovery	  team)• 2016	  Kavli Prize	  in	  Astrophysics	  (Drever,	  Thorne	  and	  Weiss)	  • Shaw	  prize	  in	  Astronomy (Drever,	  Thorne	  and	  Weiss)	  • 2016	  Gruber	  Foundation	  Cosmology	  Prize (Drever,	  Thorne,	  Weiss	  and	  the	  LIGO	  discovery	  team)

ThorneJan/26/'17

Drever
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Weiss
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Gravity	  and	  Gravitational	  Waves
The	  equation	  to	  express
how	  mass	  distributions	  affectto	  space-­‐time
Einstein	  Equation

R

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6Strain	  of	  space-­‐time	  propagates	  at	  the	  speed	  of	  light
Static	  Gravity

Gravitational	  Waves

Very	  heavy	  masses
non-­‐axial	  symmetrical moving
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LIGO	  Caught	  Signals
from	  Binary	  Black	  Holes!
Credit:	  LIGO	  Scientific	  Collaboration

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8Advanced	   LIGO:
Laser	  Interferometric GW	   detectors
Livingston	  Observatory	  (LLO)

Louisiana

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Hanford	  Observatory	  (LHO)

Washington

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9What	  are	  the	  Signals	  Like?

LIGO	  Scientific	  Collaboration,	  PRL	  1 06,	  0 61102	  (2016)

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10PRL	  106,	  061102	  (2016)

Change	   of	  the	   frequencies→36	  M◎ &	  29M◎
Frequencies
after	  merger	  →Mass	  62	  M◎Amplitude	  →	   Distance (400Mpc)~350km	  apart

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62-­‐(36+29)= 3	  M◎ energy	   emit11Impact	  of	  the	  Discovery• The	  first	  observation	  of	  space-­‐time	  strain	  due	  to	  GWs
• The	  signals	  do	  not	  contradict	  against	  GR• The	  first	  observation	  of	  binary	  black	  holes• The	  first	  observation	  of	  the	  binary	  black	  hole	  merger• The	  first	  observation	  of	  30M◎ black	  holes

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12Surprise!
1. The	  signals	  came	  just	  before	  the	  official	  start	  of	  the	  first	  observation	  run2. People	  anticipated	  the	  first	  signals	  would	  be	  from	  binary	  neutron	  starts
3. Observed	  BHs	   had	  ~30	  solar-­‐mass

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The	  Second	  Event,	  GW151226
Another	  BBH	  merger!
Phys.	  Rev.	  Lett.	  116,	  2 41103	  (2016)

LHO

LLO

21M◎
14	  M◎

7	  M◎
1.4	  billion	   light	   years

Black	  hole	  mergers	  exist	  more	  than	  we	  assumed?
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30	  Solar-­‐mass	  Black	  Holes

There	   are	  supermassive	  (>106M◎)	  BHs

LIGO;	  https://www.ligo.caltech.edu/image/ligo20160615e
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30	  Solar-­‐mass	  Black	  HolesHow	  30M◎ black	  holes	  were	  formed?
Star	  formation	  in	   the	   current	  universe
Inter	  Stellar
Matters	  Gather

Gas
Compressed

Nuclear
Fusion	  starts

Outer	  layer
Explosion

Star	  formation	  of	  1st GEN	   starts
Nuclear
FusionstartsInter	  Stellar
Matters	  Gather

Gas
CompressedInter	  Stellar	  Matter
keep	  gathering

Figure:	  Moonrunner Design/Nikkei	  Science 2016	  May	  Issue

The	  observed	  black	  holes	  might	  be from	  the	  early	  universe?

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Kinugawa	  et	  al,	  MNRAS	  4 42,	  2 963–2992	  (2014)16

Conventional	  observations	  withelectro-­‐magnetic	  waves

Observations	  with
Gravitational	  waves

hubblesite.org

Subaru	   Telescope

Illustration:	  Sora Kawamura

Photo	  album	  for13	  billion	  years	  of	  the	  universe
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Sound	  track	  of	  the	  universe
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Contents• Gravitational	   Wave	  (GW)	  Detection• About	  the	  Interferometric Detectors• Japanese	  Project,	  KAGRA• Future	  Prospects• (If	  we	  have	  time)	  Additional	  Stories

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When	  GWs	  come	  to	  Earth…

TimeStrains	  of	  space-­‐timechange	  the	  distance	  between	  masses
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How	  much	  is	  the	  change?
As	  small	  as	  a	  hydrogen	  atom	  size	  changefor	  an	  Earth-­‐Sun	  distance!	  
1.5	  x	   1011m

10-­‐10m

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Fraction	  of	  the	  distance	  change＝

10-­‐10m / 1011m＝

10-­‐21

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20Laser	  Interferometer• ビデオMirror• マイケルソン

MirrorBeam	  Splitter

Laser
Photo	  Detector

21Interfering• ビデオ• マイケルソン

Goes	  Bright22

Laser	  Interferometer
MirrorMirrorBeam	  Splitter

Laser
Photo	  Detector

23Interfered	  Light	  at	  Photo	  Detector• ビデオ• マイケルソン

Goes	  Dark

24

Research	  Field	  of	  GW	  Detection
Extremely	  difficult	   measurement

No	   Signal	   for	  100	  years

Astrophysics

Data	  Analysis

Detector	   Development

General	   Relativity

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Towards	  Higher	  Sensitivity
mirrorLonger	  is	  better!
ΔL = h x LmirrorBeam	  Splitter	  (BS)
Dark	  port
Laser
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Amplifying	  the	  signals
mirrorOptical	   cavity	  where	  the	   laser	  lightis	   circulated	  (Fabry-­‐Perot	  cavity)

Power-­‐recycling	  mirror
to	   recycle	  the	   laser
coming	   back	  from	  the	   ifo

BSLaser
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mirrorSignal-­‐recycling	   mirror
to	   tune	   the	   sensitivefrequency	  bandwidth
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Controlling	  the	  IFOLengths	   of	   optical	   cavities
must	   be	   the	   integer	   multipleof	  the	   laser	  wave	  length

L=Nλλ： laser	   wave	  length
N： Integer

ミラー

L

aLIGO &	  KAGRA	  have	  5	  DoF to	   control
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Fundamental	  Noises	  in	  IFOGWsLaser	  fluctuations

Mirror	  fluctuations• Shot	  Noise• Radiation	  Pressure	  Noise• Seismic	  Noise• Thermal	  Noise

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Seismic	  Noise• Seismic	  motions	  (earthquakes)	  on	  the ground	  shake	  mirrors→	  Suspend	  the	  mirrors

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30Vibration	  Isolation	  Systems	  in	  LIGOAdvanced	  LIGO’s	  quadruple	  suspension

Cumming	  et	  al.,	  CQG	  29	  ( 2012)	  035003

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Platform	  with	  active	   vibration	  isolation

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Thermal	  Noise
Noise	  due	  to	  interferometer	  being	  in	  a	  thermal	  bath
ThermalBathTo	   reduce	   thermal	   noise,• Low	  temperature	   is	  better• High	  quality	  (Q)	  factor	  is	  better
Silica	   Mirror
Monolithic	   suspension	  ear

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Two	  kinds	  of	  Quantum	  Noise
Photon	  numbers	  (power)	  can’t	  be	  exactly
measured	  because	  of	  their	  quantum	  nature:N	  numbers	  of	  photons	  fluctuate	  sqrt(N)1.	  Radiation	  Pressure	  Noise
hrad ∝ √P02.	  Shot	  Noisehshot ∝ 1/√P0
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Reducing	  Shot	  Noise in	  aLIGO
180W	  high	   power	  laserPre-­‐stabilized	   high	   power	  laser

Injecting	   Squeezed	  Vacuum	  iLIGO demonstrated shot	   noise	  reduction
with	   squeezed	   vacuum
nature	  photonics	  ( 2013)
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My	  Experiences	  in	  LIGO	  Livingston	  2011-­‐2014

“The	  South”

Jul	  2 7st,	  '16

お茶の水女子大学ワークショップ

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My	  Experiences	  in	  LIGO	  Livingston	  2011-­‐2014
Around	  50	  people	  at	   the	   site
• ~5	  Scientists• ~5	  Postdocs• 5-­‐10	  Grad	  students• ~20	  Engineers• ~3 Computer	   Admins• ~3	  Assistants
Typical	   Day6am-­‐10am:	  Noisy	  work	  (cleaning,	  construction...)10am-­‐6pm：Hardware	  installation,	   integration
6pm	  -­‐：Interferometer	  commissioning
7/12/2016

LIGO-­‐G1601440	  /	  JGW-­‐G1605343	  More	  scientists	   come	  fromCaltech	   and	  MIT(the	  host	  institutions)when	  something	  important37

aLIGO IFO	  Commissioning
Commissioning…
Interferometers	  wouldn’t	   even	  work
only	  with	   parts	   installed
Complex	   subsystems	  must	   be	   properly
Integrated	  as	   an	   interferometer	   to	  function

４kmHuge	   system	  and	   thousands	  of	  parts	   behaviors
must	   be	   understood	   and	  mechanically,	   optically	  controlled“Control”

resonant
38

LLO	  Interferometer
Commissioning

LIGO	  Magazine,	  vol 5,	  p.10

Noise	  Hunting
7/12/2016

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Technical	  Noises
Once	  the	  interferometer	   work,
then	  technical	  noises	  must	  be	  huntto	  make	  high	  sensitivity

Suspension	  	  sensor	  noise

Seismic	  noise

Suspension	  thermal	  noise

Residual	  gas

Mirror ’s	  angular	  fluctuations

Laserfrequency
and	  intensity	  noise

Mirror	  thermal	  noise

Radiationpressure noise Acoustic
noise

Magnetic	  noise
Temperature	  fluctuation
Photonshot	  noise

Photo	  sensor
electric	  noise

GW	  Channel
40Actual	  Sensitivity	  of	  aLIGO
LIGO	  Observation	  Run	  1	  Phys.	  Rev.	  Lett 116,	  131103	  (2016)
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Observation	  Plan	  of	  aLIGO

Living	  Rev.	  Relativity	  1 9	  (2016),	  1• 2	  times	  better	  sensitivity	  for	  the	  next	  run→	  8	  times	  more	  volume	  to	  cover• More	  events	  for	  BH-­‐BH,	   NS-­‐NS	  →	  reveal	  population,	  mass	  distribution• Deeper	   study	  for	  the	  scenario	  of	  Binary	  compact	  star	  formation• More	  accurate	  comparison	  against	  GRJan/26/'17

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Observation	  Run	  2	  Started!
Observation	   for	  6	  months	  with	  a	  few	  months	  brake	  for	  smaller	  upgrades• Better	  photo	  detector	   at	  the	  GW	  channel• Better	  mode	  matching	  in	  the	  signal	  recycling	  cavity• After	  the	  brake,	  VIRGO	  joins	  the	  observation	  LIGO	  Control	  Room	   (2014)

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Contents• Gravitational	   Wave	  (GW)	  Detection• About	  the	  Interferometric Detectors• Japanese	  Project,	  KAGRA• Future	  Prospects• (If	  we	  have	  time)	  Additional	  Stories

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Mozumi Village

Views	  ofKamioka(Hida,	  Gifu)

Kamioka Town

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Projects in Kamioka
XMASSKamland

Mt.	   Ikenoyama
Super-­‐K
CLIO

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Projects in Kamioka
Old	  tunnel

XMASS

Kamland
GW	  office(Control	  Room)

Mt.	   Ikenoyama
Super-­‐K
CLIO

New	  A totsu Entrance

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Our	  Office	  in	  WinterJan	   16…
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KAGRA	  Tour

Winter

Entrance

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In	  winter,	  we	  have	  snow	  and	  even	  avalanches...
Movie	   by	  N	  Kimura

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Central	  Experiment	  Area
YTo	  3 km tunnel

BSX

BS

DetectionPort

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513km arm	  tunnels

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KAGRA	  Features
1.	  Underground	  Site

X arm

Plot	  by	  A 	  Shoda,	  JGW-­‐G1605219

Tall	   Suspensions

Italy

Tokyo

KAGRA	  tunnel

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KAGRA	  Features
2.	  Cryogenic	  Mirrors

Sapphire	  mirrors（High	  Q	  in	  cryogenic	  temperature）

Cool	   mirrors	  down

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Working Underground...

Electric	  cars	  (Mitsuoka	   Like-­‐T3)

Mine	  Work	  Style••••••Work	   cloths,	  work	  gloves,	  work	  boots
Helmets
Head	   lights
Reflect	   vests
Oxygen	  sensors
Electric	   bicycles

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KAGRA	  Control	  RoomAll	   data	   is	   on	  the	   network	  dedicatedfor	  the	  control	  and	  data	   acquisition
10G	  optical	   fiber	   network	  is	   connectedfrom	  the	   control	  room	  to	  the	  mine

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KAGRA	  Timeline
2010 2011
Project	  Start
TunnelInitialConstruction2012 2013 2014 2015 20162017 20182019

1yr	  delay	  due	  tothe	   earthquake

Test	  Operation

Large Suspensions
Cryogenic

Cryogenic
Cryogenic	  Test	   Operation

UpgradesOptical	   layout	  upgrades,	  Sensitivity	   improvements• bKAGRA-­‐1	  (simple	  Michelson	  with	   large	  suspensions	   in	   a	  cryogenic	  temperature)	   is	   planned	  in	  fiscal	  year	  of	   2018
• Further	  sensitivity	   improvement	   afterwards• Astrophysics	  possible	   around	  2020?	  	  (My	  personal	   guess!)
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Aim	  of	  bKAGRATo	  Join	  the	  international	  observation	  networkwith	  LIGO	  equivalent	  sensitivity

Direction	  of	  GW150914,	  600	  deg2(cf. Summer	  triangle	  420	  deg2)
LIGO:	  https://www.ligo.caltech.edu/image/ligo20160615b

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58International	  network
Using	  the	  arrival	  times	  of	  the	  GW	  signals,
the	  sky	  position	  of	  the	  GW	  source	  can	  be	  identified

Supernovae,
Black	   hole	   mergers
・・・

VIRGO
LIGO
Three	   detectors	   should	  have
similar	  sensitivities
KAGRA

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More	  detector	  is	   betterto	   cover	  the	   whole	   sky59Aim	  of	  bKAGRATo	  join	  the	  international	  observation	  networkwith	  equivalent	  sensitivity	  of	  LIGO

LIGO	  2	  IFOs＋VIRGO(2019 plan）
x	   is	   a	  blind	   spot

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LIGO	  2IFOs	  ＋ VIRGO	  +	   One	  more

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Multimessenger Astrophysics

Diversified	   observations	   withVisible,	  Radio,	  X	  ray,Gamma	  ray	  and	  Neutrino	  Telescopes

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Contents• Gravitational	   Wave	  (GW)	  Detection• About	  the	  Interferometric Detectors• Japanese	  Project,	  KAGRA• Future	  Prospects• (If	  we	  have	  time)	  Additional	  Stories

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Future	  of	  GW	  Astronomy• Einstein	  Telescope	  (ET)and	  LIGO	  next	  generation– 10km	  scale– Underground	  (ET)– Cryogenic• LISA,	  DECIGO– Space	  based	  detectors– 0.1~10mHz	  (LISA),	  0.1-­‐1Hz	  (DECIGO)– Cosmological	  targets,	  Intermediate	  mass	  BHwww.lisa.nasa.org
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Acknowledgement
KAGRA	  is	  supported	  byMEXT,	   JSPS	  Leading-­‐edge	  Research	  Infrastructure	  Program,	  JSPS	  Grant-­‐in-­‐Aid	   for	  Specially	   Promoted	   Research	   26000005,	  MEXT	  Grant-­‐in-­‐Aid	   for	  Scientific	  Research	   on	  Innovative	  Areas	  24103005,	  JSPS	  Core-­‐to-­‐Core	  Program,	  A.	  Advanced	  Research	  Networks,	  and	  the	  joint	  research	   program	  of	  ICRR	  Jan/26/'17

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