status and prospects for ligo barry c. barish caltech 17-march-06
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Status and Prospects for
LIGO
Barry C. BarishCaltech
17-March-06St Thomas, Virgin Islands
Crab Pulsar
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LIGO
Livingston, Louisiana
4 km
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LIGO
Hanford Washington
4 km
2 km
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Interferometer optical layout
laservarious optics
10 W 6-7 W 4-5 W 150-200 W 9-12 kW
vacuum
photodetector
suspended, seismically isolated test masses
GW channel
200 mW
modecleaner
4 km
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LIGO Beam Tube
• 1.2 m diameter - 3mm stainless 50 km of weld
• 65 ft spiral welded sections
• Girth welded in portable clean room in the field
• Minimal enclosure
• Reinforced concrete
• No services
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LIGOvacuum equipment
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Core Optics installation and
alignment
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LIGO Opticsfused silica
Caltech data CSIRO data
Surface uniformity < 1 nm rms Scatter < 50 ppm Absorption < 2 ppm ROC matched < 3% Internal mode Q’s > 2 x 106
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Interferometer Noise Limits
Thermal (Brownian)
Noise
LASER
test mass (mirror)
Beamsplitter
Residual gas scattering
Wavelength & amplitude fluctuations photodiode
Seismic Noise
Quantum Noise
"Shot" noise
Radiation pressure
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What Limits LIGO Sensitivity? Seismic noise limits low
frequencies
Thermal Noise limits middle frequencies
Quantum nature of light (Shot Noise) limits high frequencies
Technical issues - alignment, electronics, acoustics, etc limit us before we reach these design goals
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Commissioning /Running Time Line
NowInauguration
1999 2000 2001 2002 20033 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4
E2Engineering
E3 E5 E9 E10E7 E8 E11
First Lock Full Lock all IFO
10-17 10-18 10-20 10-21
2004 20051 2 3 4 1 2 3 4 1 2 3 4
2006
First Science Data
S1 S4Science
S2 RunsS3 S5
10-224K strain noise at 150 Hz [Hz-1/2]4x10-23
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Evolution of LIGO Sensitivity S1: 23 Aug – 9 Sep ‘02 S2: 14 Feb – 14 Apr ‘03 S3: 31 Oct ‘03 – 9 Jan ‘04 S4: 22 Feb – 23 Mar ‘05 S5: 4 Nov ‘05 -
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Initial LIGO - Design Sensitivity
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102
103
10-23
10-22
10-21
10-20
10-19
10-18
Frequency (Hz)
Eq
uiv
alen
t st
rain
no
ise
(Hz-1
/2)
H1, 20 Oct 05L1, 30 Oct 05SRD curve
Rms strain in 100 Hz BW: 0.4x10-21
Sensitivity Entering S5 …
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S5 Run Plan and Outlook
Goal is to “collect at least a year’s data of coincident operation at the science goal sensitivity”
Expect S5 to last about 1.5 yrs
S5 is not completely ‘hands-off’
Run S2 S3 S4S5
Target
SRDgoal
L1 37% 22% 75% 85% 90%
H1 74% 69% 81% 85% 90%
H2 58% 63% 81% 85% 90%
3-way
22% 16% 57% 70% 75%
Interferometer duty cycles
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Sensitivity Entering S5 …Hydraulic External Pre-Isolator
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Locking Problem is Solved
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What’s after S5?
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“Modest” Improvements
Now – 14 Mpc
Then – 30 Mpc
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Astrophysical Sources
Compact binary inspiral: “chirps”» NS-NS waveforms are well described» BH-BH need better waveforms » search technique: matched templates
Supernovae / GRBs: “bursts” » burst signals in coincidence with signals in
electromagnetic radiation » prompt alarm (~ one hour) with neutrino
detectors
Pulsars in our galaxy: “periodic”» search for observed neutron stars (frequency,
doppler shift)» all sky search (computing challenge)» r-modes
Cosmological Signal “stochastic background”
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Our Searches
BNS
PBH
Spin is important
“High mass ratio”Coming soon
1
3
100.1
Mass
Mass0.1 1 3
10
Inspiral-Burst S4
Several inspiral searches are performed currently:» Primordial black holes
binaries (PBHB)» Binary Neutron Stars (BNS)» Binary Black Holes (BBH)
Other searches in progress» Spinning Black Holes» Coincidences with GRB» Black Hole Ringdown» Inspiral-Burst
BBH
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Template Bank
Covers desiredregion of massparam space
Calculatedbased on L1noise curve
Templatesplaced formax mismatchof = 0.03
2110 templatesSecond-orderpost-Newtonian
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Binary Neutron Star Search Results (S2)
cum
ulat
ive
num
ber
of e
vent
s
signal-to-noise ratio squared
Rate < 47 per year per
Milky-Way-like galaxy
Physical Review D
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Binary Black Hole Search
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From Limit Setting to Detections
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Improving Sensitivities
Effective distance of L1 improved – S3S4
8 Mpc to 40 Mpc
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Binary Inspiral Search: LIGO Ranges
Image: R. Powell
binary neutron star range
binary black hole range
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Astrophysical Sources
Compact binary inspiral: “chirps”» NS-NS waveforms are well described» BH-BH need better waveforms » search technique: matched templates
Supernovae / GRBs: “bursts” » burst signals in coincidence with signals in
electromagnetic radiation » prompt alarm (~ one hour) with neutrino
detectors
Pulsars in our galaxy: “periodic”» search for observed neutron stars
(frequency, doppler shift)» all sky search (computing challenge)» r-modes
Cosmological Signal “stochastic background”
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‘Unmodeled’ Burstssearch for waveforms from sources for which we cannot currently make an accurate prediction of the waveform shape.
GOAL
METHODS
Time-Frequency Plane Search‘TFCLUSTERS’
Pure Time-Domain Search‘SLOPE’
freq
uen
cy
time
‘Raw Data’ Time-domain high pass filter
0.125s
8Hz
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Burst Search Results Blind procedure
gives one event candidate» Event immediately
found to be correlated with airplane over-flight
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Burst Source - Upper Limit
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Astrophysical Sourcessignatures
Compact binary inspiral: “chirps”» NS-NS waveforms are well described» BH-BH need better waveforms » search technique: matched templates
Supernovae / GRBs: “bursts” » burst signals in coincidence with signals in
electromagnetic radiation » prompt alarm (~ one hour) with neutrino
detectors
Pulsars in our galaxy: “periodic”» search for observed neutron stars
(frequency, doppler shift)» all sky search (computing challenge)» r-modes
Cosmological Signal “stochastic background”
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Detection of Periodic Sources
Pulsars in our galaxy: “periodic”» search for observed neutron stars » all sky search (computing challenge)» r-modes
Frequency modulation of signal due to Earth’s motion relative to the Solar System Barycenter, intrinsic frequency changes.
Amplitude modulation due to the detector’s antenna pattern.
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Directed Pulsar Search
28 Radio Sources
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Einstein@Home
LIGO Pulsar Search using home pc’s
BRUCE ALLENProject Leader
Univ of Wisconsin Milwaukee
LIGO, UWM, AEI, APS
http://einstein.phys.uwm.edu
ALL SKY SEARCH enormous
computing challenge
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All Sky Search – Final S3 Data
NO Events
Observed
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Astrophysical Sources
Compact binary inspiral: “chirps”» NS-NS waveforms are well described» BH-BH need better waveforms » search technique: matched templates
Supernovae / GRBs: “bursts” » burst signals in coincidence with signals in
electromagnetic radiation » prompt alarm (~ one hour) with neutrino
detectors
Pulsars in our galaxy: “periodic”» search for observed neutron stars (frequency,
doppler shift)» all sky search (computing challenge)» r-modes
Cosmological Signal “stochastic background”
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Signals from the Early Universe Strength specified by ratio of energy density in GWs to
total energy density needed to close the universe:
Detect by cross-correlating output of two GW detectors:
d(lnf)
dρ
ρ
1(f)Ω GW
criticalGW
Overlap Reduction Function
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Stochastic Background Search (S3)
Fraction of Universe’s
energy in gravitational waves:
(LIGO band)
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Results – Stochastic Backgrounds
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Conclusions LIGO works! Data Analysis also works for broad range of
science goals. Now making transition from limit setting to detection based analysis
Data taking run (S5) to exploit Initial LIGO is well underway and will be complete within ~ 1.5 years
Incremental improvements to follow S5 are being developed. (improve sensitivity ~ x2)
Advanced LIGO fully approved by NSF and NSB and funding planned to commence in 2008. (design will improve sensitivity ~ x20)
R&D on third generation detectors is underway
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