Pia Astone LIGO/Virgo collaborations - The discovery of gravitational waves and the contribution of optical technologies - ENEA-Frascati
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The discovery of gravitational waves and the
contribution of optical technologies
Pia Astone
LIGO/Virgo collaborations
VIRGO ha iniziato la presa dati nel 2003
E ha rivelato il primo segnale nel 2017
www.virgo-gw.eu
www.ego-gw.it
2
1.3 billion years ago….Merger of a binary black holes system
3
14 September 2015 @ 9:50 UTC
Earth deformation 10-14 m
4
P HYSICAL
REVIEW
Member Subscription Copy
L ETTERS
Articles published week ending
™
12 FEBRUARY 2016
Library or Other Institutional Use Prohibited Until 2017
Published by
American Physical Society™ Volume 116, Number 6
5
The first direct observation of GWs
and of the merger of two BHs
6
E= Mc2
M=JJJ
3 Soli convertiti in onde gravitazionali
50 volte la luminosità di tutte le stelle
Circa l’energia che l’umanità consuma in
un miliardo di miliardi di miliardi di anni
…in frazioni di un secondo !
Credit D. Shoemaker 7
Verification of GR
predictions
Studies of extreme
systems
8
Verification of GR
predictions
Studies of extreme
systems
9
More than 50 years of work.
Different experiments and techniques
Nautilus @ LNF
90’: Cryogenic Bars
60’: Joe Weber
pioneering work
Guido Pizzella
Edoardo Amaldi 10
2000’ - : Large InterferometersGlobal GW detector network
LIGO Livingston (LA, USA): 4 km dual GEO600 (Hannover, GE):
recycled Fabry-Perot Michelson IFO 600 m folded arms dual recycled
Michelson
VIRGO (Cascina,
IT):
3 km power
recycled Fabry-
Perot Michelson
Super-attenuator
seismic isolation
LIGO Hanford
(WA, USA):
4 km dual
recycled
Fabry-Perot KAGRA (Hida-city,
Michelson IFO JP): UNDER
CONSTRUCTION
(2019+)
LIGO-India (IndIGO):
• Advanced LIGO started taking data in September 2015 PLANNED (2022+)
• Advanced Virgo joined on August 2017
• By 2019, sensitivity expected to improve by a factor of 10
relative to initial detectors 11!"
h= ~ 10-21
"
10-18 m = raggio classico del protone
The Garching delay line
12!"
h= ~ 10-21
"
10-18 m = raggio classico del protone
The Garching delay line
13Working principle
2π 4π 14
ΔϕGW = ΔLGW = hL ≈ 10 rad
−11
Long arms are needed !
λ λFabry-Perot Cavities
A Fabry-Perot cavity is a linear optical resonator consisting of two mirrors,
the highly reflecting output mirror (with a very small transmissivity) and the
input mirror with a given transmissivity coefficient
2Fcav
Fcav = 400; Lopt =L = 764 km
π
2Fcav L Storage time, proportional to the
τS =
π c number of reflections (light
bounces between the mirrors)
Phase variation is amplified 4π ⎛ 2Fcav ⎞
by the finesse factor
ΔΦ = ⎜ L⎟h
λ ⎝ π ⎠
15Main noise sources
u Quantum Noise , related to the quantum-nature of light:
• Radiation preassure ~ Plaser 1/2 photons transfer their momentum to the mirror
• Shot Noise ~ Plaser-1/2 photons in a laser beam follow a Poisson distribution
u Thermal Noise
Thermal
u Newtonian Noise
transients in the local Radiation Preassure
gravitational field
u Seismic Noise
Pcavity ~700 kW
Beam splitter Shot
Power recycling mirror
Plaser= 25 W 16Main noise sources spectrum
Strain Spectral
Amplitude (Hz)-1/2
Seismic
Passive and Active
Attenuators
Thermal
Low dissipation materials
for coatings, larger
mirrors and monolithic
suspensions
Shot
High Laser Power,
Signal Recycling
Techniques
Piero Rapagnani
Frequency (Hz)
17Nd:Yag Reduction of
P=25 W sismic vibrations
l: 1064 nm 1012 !
Infrared
Dn = 10-6 Hz
!"
h= ~ 10-21
"
10-18 m = raggio classico del protone
Foto Perciballi
18Reduction of
sismic vibrations
1012 !
!"
h= ~ 10-21
"
10-18 m = raggio classico del protone
Foto Perciballi
19Reduction of
sismic vibrations
1012 !
!"
h= ~ 10-21
"
10-18 m = raggio classico del protone
Foto Perciballi
20Reduction of
sismic vibrations
1012 !
!"
h= ~ 10-21
"
10-18 m = raggio classico del protone
Foto Perciballi
21Nd:Yag Reduction of
P=25 W sismic vibrations
l: 1064 nm 1012 !
Infrared
Dn = 10-6 Hz
!"
h= ~ 10-21
"
10-18 m = raggio classico del protone
Foto Perciballi
22OPTICS: mirror and beam splitter
Substrate: SiO2
35 cm diameter
20 cm width
Beam splitter
Mass 42 kg (was 21 kg) 55 cm diameter
Homogeneity < 5 x 10-7
Surface Uniformity < 1 10 -9 m
6.5 cm width
23Foto Perciballi
24
Foto Perciballi
Foto PerciballiPower Recycling
Injection
Foto Perciballi
North arm
Detection
Beam Splitter
The vacuum system: to reduce light diffusion
A volume of 7000 m3 at 1 atmosphere/1012 !
2526
On August 1st 2017 Advanced Virgo joined Advanced LIGO in O2
O2 : November 30, 2016 – August 25, 2017
27GW170814: A Three-Detector Observation of Gravitational
Waves from a Binary Black Hole Coalescence
Phys. Rev. Lett. 119, 141101 – 6 October 2017
The second LIGO science run
O2 started on Nov, 30 2016.
Virgo joined on Aug. 1st
SNR=7.3 SNR=13.7 The run ended on Aug. 25th
SNR=4.4
Sky position localization for
GW170814 is within an area
of ~100 deg2
Radiated GW energy ~ 2.7 Mo c2
28Credit NASA GW170817 29
Matter and light !
q The Fermi Gamma-ray
Burst Monitor
independently detected a
gamma-ray burst
(GRB170817A) with a
time-delay of ~1.7 s with
respect to the merger
time.
qConfirmed by INTEGRAL
qBinary neutron star
(BNS) mergers are
progenitors of (at least
some) SGRBs
The Astrophysical Journal Letters, 848:L13
(27pp), 2017 October 20 3031
32
Sky Localization
Higher latency localisation LIGO-Virgo ~30 deg2 Location of the
190 host galaxy NGC
deg2 4993 in the
Swope optical
discovery image
at 10.9 h after the
merger
Credit: G. Greco INAF
~30 deg2
Rapid localisation LIGO:
190 deg2 Phys. Rev. Lett. 119, 161101(2017) 3334
With one signal……
35< 2 years of gravitational-wave
astronomy
we
40 years of X-ray astronomy
36
Credit D. Reitze G1702248-v1Interstellar
37Interstellar
38Information and data release @....
https://losc.ligo.org/events/
Discovery and related papers collected at
dcc.ligo.org
39² Einstein Telescope (2018-2020): 10 km arm length, triangular underground cryogenic
detector. CQG, 2010, 27, 084007
² LIGO Voyager (2025-2030): cryogenic (120 K) high power; x3 improvement in aLIGO
strain sensitivity
² LIGO Cosmic Explorer (2030+): new 40 km arm length interferometer
Sardinia is
a possibility
40The next scientific run
will start at the end of 2020 ~ 600
Mly
this year
Now ~ 300
Mly
Gravitational Wave
Astronomy is just 2010 ~ 65
started Mly
100
million
light Images: R. Powell, The Atlas
years of The Universe,
http://www.anzwers.org/free/
41
universe/index.htmlStoccolma, Dicembre 2017
Celebrazioni per la consegna
del Premio Nobel a Weiss,
Thorne, Barish
Is this a
”once in your life” ?
event ?
….Stay tuned !! 42You can also read
