LHOCE??

LLO

LIGO : Past, Present and Future

Hiroaki Yamamoto
Many slides from presentations at LVK Sep.2020,
including talks by D.Reitze, R.Adhikari, G.Vajente, CBC, et al.
LIGO-G1901066-v4
Image
Credit: Gabriele Vajente

Hiro Yamamoto

ICRR
seminaron December 21, 20201
ICRR
December21, 2020

LIGO
History!

!

RonaldDrever(1931~2017)

1965~ (Stan Whitcomb, APS April Meeting, 15 April 2019)

Kip Thorn(CIT)» Developing the GW interferometer concept» Understanding noises – seismic, thermal, shot, gas…
» Unifying efforts to build LIGO (CIT/MIT/NSF)

Ron Drever (Glasgow→CIT)

1994~2008~» Building advanced LIGO for the GW signal detection– aLIGO = iLIGO + GEO (Hannover)“Blue Book” by Weiss and …
Barry Barish (CIT, SSC → LIGO)--- 1st generation --Power Recycling FP Michelson
Single suspension
10W 1μ laser--- 2nd generation --Dual Recycling FP Michelson» O1/O2 observation runs from 2015 Sept, one signal / month– Detection of the first GW signal from BBH and from BNS!

40m at CIT1989 LIGO Proposal by Vogt and…

» Building initial LIGO for the real size R&D» Organizing LIGO Scientific Collaboration» Operating initial LIGO at design sensitivity for one year!

Rai Weiss(MIT)with stable recycling cavities
Quadruple suspensions» O3 started April 1, 2019 and one signal / 1.5 week
– Public announcement of candidates via GCN circular» Upgrades toward the design sensitivity

25~120W 1μ laser

2025~

Better coating to reduced thermal
2 noiseLIGO-G1901066-v4

Hiro Yamamoto--- 3rd generation --Squeezing – frequency independent tofrequency dependent

ICRR December 21, 2020
Cryogenic, 2μ laser, Silicon, …

» Building the observatory for astronomy and cosmology

Advanced LIGO, H1 & L1
in the International GW NetworkGEOHannover 600m

aLIGO, Hanford, 4km

KAGRA
Kamioka, 3km~2019

aLIGO Hanford, 4 km

3000km ~ 10ms
2015

2017
AdVirgo, Cascina, 3km
AdV, Cascina, 3 km

aLIGO Livingston, 4 km

LIGO-India
Hingoli, 4km

~2025

2019

aLIGO, Livingston, 4km
BNS inspiral range
3Virgo cluster

16Mpc

おとめ座銀河団5400万光年

LIGO-G1901066-v4Duty factor

Hiro Yamamoto

21ICRR December 21, 20203courtesy of M.Evans

Sensitivity and significanceor how far can we hear

54Mly = 16.5 Mpc

Phys. Rev. X 6, 041015 (2016)

100M ly ~ 30Mpc

1pc=3.26 light year
Event rate ~ r3
Strain ~ M5/3
M(BBH) ~ 10 M(BNS)

Coverage of 1st generation IFO

1.3B ly ~ 400Mpc

GW150914

GW151226

GW151012

LIGO-G1901066-v4

Hiro Yamamoto

Coverage of 2nd generation IFO
ICRR December 21, 20204

Noise sources of GW detectors- disturbance of L1-L2 FP makes the arm length 100 times longer
No direct actuation
Seismic motion < 50 Hz
Thermal noise~ 100 Hz
L2
L1
Radiation Pressure< 50 Hz
Shot noise> 500 Hz
LIGO-G1901066-v4

Hiro Yamamoto

ICRR December 21, 2020

Advanced LIGO IFO (DRFPMI)+ frequency independent squeezer for O3
Active Seismic Isolation

40 kg ‘Test Mass’ Mirror

70W amp & PMC for 50W output

Input Optics
Output Mode Cleaner

Squeezer

Auxiliary Laser

LIGO-G1901066-v4

Hiro Yamamoto

ICRR December 21, 2020

Signals in O1(2015/9/12~2016/1/19),
O2(2016/11/30~ 2017/8/25)
O3a (2019/4/1~2019/10/1)[2]

GW170817 (O2)
<2.8M⦿, 40Mpc

O3, N=56(non-retracted alerts)[1]O2, N=8[4]O1, N=3[3]GW150914 (O1)63.1M⦿, 430Mpc

O3a O3b[1] GW190412 : 30.0M⦿+8.3M⦿→ 37.3M⦿, 570~880Mpc, R. Abbott et al. (LIGO Scientiﬁc, Virgo), GW190412: Observation of a BinaryBlack-Hole Coalescence with Asymmetric Masses, Phys. Rev. D 102, 043015 (2020)[2] GW190425 : 2.0M⦿+1.4M⦿→ 3.4M⦿, 90~230Mpc, B. P. Abbott et al. (LIGO Scientiﬁc, Virgo), GW190425: Observation of a Compact
Binary Coalescence with Total Mass ∼ 3.4M⦿, Astrophys. J. Lett. 892, L3 (2020)[3] GW190521 : 85M⦿+66M⦿→ 142M⦿, 2.7~7.7Gpc, R. Abbott et al. (LIGO Scientiﬁc, Virgo), GW190521: A Binary Black Hole Merger
with a Total Mass of 150 M☉, Phys. Rev. Lett. 125, 101102 (2020), R. Abbott et al. (LIGO Scientiﬁc, Virgo), Properties and astrophysicalimplications of the 150 M⦿ binary black hole merger GW190521, Astrophys. J. Lett. 900, L13 (2020)[4] GW190814 : 23.2M⦿+2.6M⦿→ 25.6M⦿, 196~282Mpc, R. Abbott et al. (LIGO Scientiﬁc, Virgo), GW190814: Gravitational Waves 7
fromthe Coalescence of a 23 Solar Mass BlackHiro
Hole Yamamotowith a 2.6 Solar Mass
Compact
Object, Astrophys.
LIGO-G1901066-v4
ICRR
December21, 2020J. 896, L44 (2020)

Events in O1 and O2
10 BBH and 1 BNS
heavy → strong, short

63.1M⦿
430Mpc35.7M⦿
1060Mpc

17.8M⦿
320Mpc80.3M⦿
2750Mpc

59.8M⦿
1020Mpc

65.6M⦿
1850Mpc

LIGO-G1901066-v4

Hiro Yamamoto

20.5M⦿
440Mpc56.3M⦿
990Mpc49.1M⦿960Mpc

53.4M⦿
580Mpc<2.8M⦿40Mpc

ICRR December 21, 2020

8

GW150914 signals

LIGO-G1901066-v4

Hiro Yamamoto

ICRR December 21, 20209

Black HoleMerger
100Hzmass, spinmass, distanceR

２A

2GM~90km
2c

800km

RS =speed = A 2π f < c
A < c / 2π f ~ 500km
LIGO-G1901066-v4

Hiro Yamamoto

ICRR December 21, 2020

10

GW from Binary Back Hole merger
O1/O2 arXiv:1811.12907, arXiv:1903.04467, O3 arXiv:2010.14529!

Direct detection of gravitational wave signals!

Observation of stellar mass black holes hierarchy up to 150M!

!

Observation of a binary black hole (BBH) system and merger!

BBH merger rate
O1/O2 : 9.7-101 Gpc-3 yr-1 to O3 : 15.3-38.8 Gpc-3 yr-1!

Test of GR in strong field:»Graviton mass upper limit : O1/O2:5x10-23 eV/c2, O3:1.76x10-23 eV/c2»Violation of general relativity : O1/O2 vs O3

LIGO-G1901066-v4

Hiro Yamamoto

ICRR December 21, 202011GW150914
Black hole merger

GW170817
Neutron star merger

LIGO-G1901066-v4

Hiro Yamamoto

ICRR December 21, 2020

12

GW170817 : Merger of neutron stars
PRL 119, 161101 (2017), Astrophys. J. Lett. 848, L12 (2017)
V1 GW170814

LIGO-G1901066-v4

Hiro Yamamoto

190 deg2 (L,H) →31 deg2 (L,H,V)

ICRR December 21, 2020

1.7340.054 sec

GW170817+GRB170817A
Electromagnetic follow-up

Astrophys. J. Lett. 848, L12 (2017)

LIGO-G1901066-v4

Hiro Yamamoto

ICRR December 21, 2020

14

GW and EM signals
from Binary Neutron Star merger
BNS merger rate : 80-810 Gpc-3 y-1 (BBH 15.3-38.8 Gpc-3 y-1 )! Confirmation of association between short GRBs and BNSmergers, and new insights into physics of GRB events.
! Limits on dynamical ejecta in the associated kilonova.
! BNS mergers as producers of heavy elements confirmed.
! Independent measurement of the Hubble constant consistent
with prior measurements.
! Test of generate relativity!

15
LIGO-G1901066-v4

Hiro Yamamoto

ICRR December 21, 2020

Binary Neutron Star merger in O2 and O3
GW170817+GRB170817A (O1/O2) Astrophys. J. Lett. 848, L13 (2017)
GW190425 (O3) Astrophys. J. Lett. 892, L3 (2020), G2001659 (CBC 2020 LVK)

GW170817

28 deg2

GW190425

LIGO-G1901066-v4

8284 deg2

Hiro Yamamoto

ICRR December 21, 202016

Exotic events in O3a
GW190521: mass of the remnant 142+28-16 M⊙
is considered an intermediate mass black hole
Network SNR:

15

FAR:

1 in 4900 yrs

Distance:

2.7 – 7.7 Gpc

Primary Mass:

85 M⨀

Secondary
Mass:

66 M⨀

Remnant
IMBH’s Mass:

GW190814: The secondary, 2.6 M⊙, is heavier
than known NSs and lighter than known BHs.
Network SNR:Model 1
Model 225

FAR:

1 in 8.3~1300
yrsDistance:

196-282 Mpc

Primary Mass:

142 M⨀

23.2 M⨀

SecondaryMass:

2.6 M⨀

Remnant
IMBH’s Mass:

25.6 M⨀

S/N=10.6
S/N=21.6
S/N=4.5
LIGO-G1901066-v4

Hiro Yamamoto

ICRR December 21, 202017

New in O3: Open Public Alerts!

Preliminary GCN Notice will be sent out autonomously in low latency(~minutes) for event candidates meeting given FAR»FAR threshold targets an overall astrophysical purity of 90%– 1 / 2 months overall for CBC– 1 / year overall for Burst»»»!

Preliminary Notice will be followed by:»»!

Initial Notice and Circular confirming the event (~4h), following human vetting by a smaller number ofempowered advocates
A retraction (latency dependent on the event type)

LIGO/Virgo Public Alerts User Guide & Support»»!

Modified FAR will be used for candidates with EM counterparts
These alerts will be publicly available through the Gamma-ray Coordinates Network (GCN)
Event candidates will be publicly available in https://gracedb.ligo.org

https://emfollow.docs.ligo.org/userguide/quickstart.html
contact+emfollow/userguide@support.ligo.org

openlvem mailing list»»Instructions at https://wiki.gw-astronomy.org/OpenLVEMThis is a public list to which anyone can subscribe

LIGO-G1901066-v4

Hiro Yamamoto

When GW150914 wasdetected, it wasprohibited to talk about
it for a half year, even tofamily.

ICRR December 21, 2020

Open data!

https://www.gw-openscience.org/!

All data of O1, O2, O3a!

Getting Started!

Bulk data access example

LIGO-G1901066-v4

Hiro Yamamoto

ICRR December 21, 202019

Observing Scenario: Run Plans
arXiv:“Prospects for Observing and Localizing Gravitational-Wave
Transients with Advanced LIGO, Advanced Virgo and KAGRA”

LIGO-G1901066-v4

O4, N=170(simulated)(non-retracted alerts)

O3, N=56

O2, N=8

O1, N=3

LIGO KAGRA Virgo LIGOIndia(A+)

O4 events Simulated
Event Stream for a one
year duration O4 runnow
O4 : no earlier than June 2022

Hiro Yamamoto

Assumptions:- 190 Mpc BNS range for H1, L1- 90 Mpc BNS range for Virgo- Same duty cycles, detector
coincidence as in O3
ICRR December 21, 2020

From O2 to O3
Mitigate Parametricinstability by acoustic ModeDampers! Laser power 25W to 50W
with 3dB squeezing! Die hard straylight mitigation!

LIGO-G1901066-v4

Hiro Yamamoto

L1 sensitivity
without squeezing &with 3dB squeezing +17Mpc

ICRR December 21, 202021

major issues
Squeeze film damping
LIGO!

LIGO-T0900582

Small gap (5 mm) between ETM and its reaction
mass increased damping from residual gas» Current poor vacuum level at LLO end station means this is asignificant thermal noise term below ~60 Hz» At expected vacuum level, squeeze film damping noise willcompete with radiation pressure noise at full power!

The conclusion
the area of theBeyond lower vacuum,
theis thatsolution
isESD
a supporting
new, annulus results in a noise level whichapproximately matches that of the ITM-CP with a 2cm gap, and that this level dominates the total
for annular(holedesigns 3cmor more.
annular reaction mass
inthickthemiddle)

6.1 ofComplicatedFailures» Provides same amountelectro-staticdrive actuation
Here byare theresults forof
a couple» Reduces damping forcea factor
2.5x of more complicateddesigns that seemed promising, but turned out not to give
good results.
The “vented”
ERM2016
has the ESD supported» Working towards possible
retrofitin early
by a 1cm thick annulus which is held 1cm away from the
11cm thick ERM by some kind of stand off, leaving theERM at 25mm from the TM. Another is the “engraved”
annular ERM in which the gaps in the ESD pattern are
cut out to a depth of 2cm, thus minimizing the surface
area which is close to the TM.

LIGO-G1901066-v4

Hiro Yamamoto

ICRR December 21, 2020

Challenge: Point Absorbers
in the Test Mass Coatings!

Point absorbers (PA) on 100%* of ETMs (10 of 10), 20%of (2 of 10) ITMs

500 ppm absorberon ETM14~40 µm!

PAs are likely embedded in the coatings; studies ofwitness samples find that PAs are primarily aluminum with ~20 µm
some traces of carbon!

3 of 4 coating vendors have PA on witness samples»Many witness samples characterized during the shutdown# witness samplesVendor% with PAstestedV167%
87
V2100%
4V350%
4V40%4!
Pursuing multi-faceted R&D approach to ‘repair’ existing
test masses!

High Res scan of 1000 ppm PA
found on ITM03»Ultrafast pulsed laser ablation: 2nd trial somewhat successful; no Al or C
found after ablation but still absorbing. Perhaps Ta?

»Chemical etching: 2 compounds being tried for Al etch, beginning Ta etch»

Mechanical milling: trial has just started

Also working with test mass coating vendor LMA toaddress problem ‘at the source’
LMA has made 2 runs with chamber modifications to eliminate
contaminants; characterization begins atLIGOYamamoto
Caltech in 2 weeksICRR
LIGO-G1901066-v4
Hiro

SEM compositional analysis of PA

Test of Femtosecond
Laser Ablation of PAs
21.7 µm

0.5 µm»December 21, 2020

23

A+ Project!

A Joint US-UK-Australia
funded project»

US budget: $20.5M–!

!

Pre-O5: 450 mm
Beamsplitter

Pre-O4»»

BNS Target Sensitivity: 190 Mpc
Frequency-dependent Squeezing– 300 m filter cavity (FC)

»Improved dark port efficiency– Low loss Faraday isolator»!

$8.0M spent/committed to date

Adaptive wavefront control

Pre-O5: Balanced
Homodyne Detection
Pre-O4: Low Loss
Faraday Isolator

Pre-O5:»

BNS Target Sensitivity: 325 Mpc»»Low coating thermal noise (CTN)
test mass coatings
450 mm beamsplitter»

Balanced homodyne

Pre-O5: Low CTN test
mass coatings (ITMs, ETMs)

Critical paths»

O4: End Station buildings &tube enclosures for new 300m
filter cavities–»

Fallback is to delay FC to preO5

O5: Test mass low thermal
LIGO-G1901066-v4
noise coating development

Pre-O4: Filter Cavity
Pre-O4:Beam Tube
Squeezed lightsource
Pre-O4: AdaptiveWavefront Control

Hiro Yamamoto

ICRR December 21, 202024

O4: Planned Detector Improvements!

q

LIGO-G1901066-v4

Hiro Yamamoto
ICRR December 21, 2020
LIGO Laboratory

25

The Path to O4!

This is the top level schedule for implement planned improvements for O4 in M1800262!

NOT SET IN STONE! The schedule is a continual work in progress and updated
frequently; note review points and definition points!

Schedule currently paced by delay in repolishing end test masses!

“O4 is currently planned to start no earlier than June 2022” in M1800277»M1800277 : Monthly status report of commissioning and detector improvement»Compiled by D.Sigg, V.Frolov, P.Fritschel, D.Coynr, C.Torrie, etc, reported to D.Reitze, A.Lazzarini

LIGO-G1901066-v4

Hiro Yamamoto
ICRR December 21, 2020
LIGO Laboratory

26

Gabriele Vajente, G2001684,OWG 2020LVK

Coating for A+LIGO-G1901066-v4

Hiro Yamamoto

ICRR December 21, 202027

3rd generation
ground-based GW detectors

https://cosmicexplorer.org

LIGO-G1901066-v4

Hiro Yamamoto

ICRR December 21, 202028

ComparingDetectors

q DeeperØ observe compact binaries at z ≳ 10q WiderØ observe heavier mergers, earlier
inspirals
q Sharper
Ø observe with greater signal-to-noise

LIGO-G1901066-v4

Hiro Yamamoto

ICRR December 21, 202029

P1900065: Astro2020 Science White Paper
Gravitational-Wave Astronomy in the 2020s and Beyond:A view across the gravitational wave spectrum

Ground-based
interferometers

pulsar-timing
arraysLIGO-G1901066-v4

Hiro Yamamoto

space-based
interferometers

ICRR December 21, 202030

US 3rd generation ground-based
interferometer timeline

LIGO-G1901066-v4

Hiro Yamamoto

ICRR December 21, 202031