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Commissioning: sensitivity progress
25W Virgo+ expected sensitivity128 effective days of data
taking but 0.02 double coincidence event expected
7
5
5
5
4
4-
3
3
4
sup
109.8 04.124 6910-J0537
108.7 56.59 Crab
105.7 68.55 1011J1913
101.1 58.50 3252J1952
108.9 46.38 2809-J1747
101.1 32.32 1034-J1833
104.1 44.30 6449J0205
100.8 38.22 Vela
Name
gwf
Compatible with some ‘exotic’ EOS
Marginally compatible with standard EOS
(Vela spin-down limit in ~80 days)
may improve on Crab
VSR2 sensitivity
Spin-down limit can be beaten for a few pulsars
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Stochastic Background (SB)
• A stochastic background can be
• a GW field which evolves from an initially random configuration: cosmological background
• the result of a superposition of many uncorrelated and unresolved sources : astrophysical background)
• Typical assumptions
• Gaussian, because sum of many contributions
• Stationary, because physical time scales much larger than observational ones
• Isotropic (at least for cosmological backgrounds)
If these are true, SB is completely described by its power spectrum
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Detection method• It is stochastic and presumably overwhelmed by noise• Need (at least) two detectors to check for statistical correlations
• Optimal filtering
SignalsUncorrelated
(?) noises
* 21 2 12
6,1 ,2
12
,
GWGW
GW
( ) ( ) ( ) ( )
( ) ( )
( ) : data from detector
( ) : overlap function between detectors
( ) : noise power spectrum in detector
( )
( )100Hz
GW
n n
i
n i
c
h f h f f fY df
f S f S f
h f i
f
S f i
dff
df
ff
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Detection performance
• Sensitivity improves as T1/2
• Better performances when coherence is high ( )– detectors near each
other compared to – detectors aligned
12
22
6,1 ,20
( ) ( )
( ) ( )GW
n n
f fSNR T df
f S f S f
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Isotropic search: results
• Data collected during S5 run (one year integrated data of LIGO interferometers)
• Point estimate of Y: no evidence of detection integrating over 40-170 Hz (99% of sensitivity)
60 6.9 10 95% C.L.
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Isotropic search: results• Now we are
beyond indirect BBN and CMB bounds
• We are beginning to probe models
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Isotropic background: constraint on cosmic strings• Parameters:
– String constant , G<10-6
– Loop size parameter – Recombination
probability p
• Additional region in the plane is excluded
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Joint LIGO/Virgo Search for GRBs
• Gamma Ray Bursts (GRBs) - brightest EM emitters in the sky– Long duration (> 2 s) bursts, high Z progenitors are likely core-collapse
supernovae– Short duration (< 2 s) bursts, distribution about Z ~ 0.5 progenitors are likely
NS/NS, BH/NS, binary merger– Both progenitors are good candidates for correlated GW emissions!
• 212 GRBs detected during S5/VSR1– 137 in double coincidence (any two of LIGO Hanford, LIGO Livingston, Virgo)
• No detections, we place lower limits on distance assuming EGW = 0.01 Mc2
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M31The Andromeda Galaxy
by Matthew T. RussellDate Taken:
10/22/2005 - 11/2/2005
Location:Black Forest, CO
Equipment:RCOS 16" Ritchey-Chretien
Bisque Paramoune MEAstroDon Series I Filters
SBIG STL-11000Mhttp://gallery.rcopticalsystems.com/gallery/m31.jpg
Refs:GCN: http://gcn.gsfc.nasa.gov/gcn3/6103.gcn3
GRB 070201
X-ray emission curves (IPN)
9 November 200739
GRB070201: Not a Binary Merger in M31!
Inspiral (matched filter search:
Binary merger in M31 (770 kpc) scenario excluded at >99% level
Exclusion of merger at larger distances
90%
75%
50%
25%
Inspiral Exclusion Zone
99%
Abbott, et al. “Implications for the Origin of GRB 070201 from LIGO Observations”, Ap. J., 681:1419–1430 (2008).
Burst search:Cannot exclude an SGR in M31
SGR in M31 is the current best explanation for this emission
Upper limit: 8x1050 ergs (4x10-4 Mc2) (emitted within 100 ms for
isotropic emission of energy in GW at M31 distance)
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The Crab Pulsar: Beating the Spin Down Limit!• Remnant from supernova in year 1054
• Spin frequency EM = 29.8 Hz
gw = 2 EM = 59.6 Hz
• observed luminosity of the Crab nebula
accounts for < 1/2 spin down power
•spin down due to:
• electromagnetic braking
• particle acceleration
• GW emission?
• early S5 result: h < 3.9 x 10-25 ~ 4X below
the spin down limit (assuming restricted priors)
• ellipticity upper limit: < 2.1 x 10-4
• GW energy upper limit < 6% of radiated energy is in GWs
Abbott, et al., “Beating the spin-down limit on gravitational wave emission from the Crab pulsar,” Ap. J. Lett. 683, L45-L49, (2008).
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Monolithic Suspensions
Strategic goal• significant scientific opportunity by increasing the sensitivity at low
frequency• unique place to test the monolithic suspension and to explore the
level of noise at low frequency before these detectors are built.
Main achievements• Optimizing the production of suspension fibers and verifying its
reliability and reproducibility• Measurement of mechanical behaviour of a dummy payload• Work on payload assembly and transport trolley• Measurements on residual losses limited by the suspension
structure.
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4 GPa
Working load
Breaking Strength Tests on Fused Silica Wires (280 microns thick)
Measurements by Glasgow group (breaking load vs thickness) K. Tokmakov et al., 2009, poster at Amaldi8
mm
• bright spots carefully removed by multiple annealing• careful cleaning of silica pieces• heads clamped without glue
IMPROVED TESTING METHOD: more reproducible loading rate
Previuos measurements (Virgo Week Nov 2009)
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Pitch TF (tx)
tx Ma/Ma DC=35 urad/VType f (hz),QP 0.244,45Z 0.399,200 P 0.402,200 Z 1.569,200 P 1.581,200 Z 1.703,200P 3.595,500P 10
tx Mi/Ma Type f (hz),QP 0.248,45Z 0.399,200P 0.402,200Z 1.703,200P 1.581,200P 3.595 400P 10
46
Noise understanding
Main contributions• Magnetic noise from
BS• External Inj Bench• Resonances in Det
bench and dihedron• Longitudinal control
noise (DSP)
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LV network performance for NSNS II
For this discussion a choice of a False Alarm Rate of 1 event per year is made. Detectors horizon for average orientation
• H 16 Mpc L 12 Mpc V 9 Mpc current situation• H 31 Mpc L 31 Mpc V 47 Mpc design
• Gain of 30 between May 2009 and design sensitivity• 6 months of stop recovered in 6 days
48
Pulsars
• Spin-down limit can be attained for more than 20 pulsars, almost all below 40 Hz.
• For five of these (that include Crab and Vela) the corresponding limit on < 10-4. (allowed by several “exotic” matter EOS
• For two < 10-5.• Crab spindown would be set at less than EGW < 10-3 Eloss
G.Losurdo - AdV Project Leader 50
AdV BASELINE DESIGNAdV BASELINE DESIGN
EGO Council - July 2nd, 2009 G.Losurdo - AdV Project Leader 50
Signal Recycling (SR)
Non degenerate rec. cavities
High power laser
High finesse3km FP cavities
Heavier mirrors
Large spot size on TM
Larger central linksCryotraps
Monolithicsuspensions
DC readout
G.Losurdo - AdV Project Leader 51
SENSITIVITY GOALSENSITIVITY GOAL
STAC - Cascina, Nov 11, 2009 G.Losurdo - AdV Project Leader 51
Reference sensitivity (125 W in the ITF): SR tuning optimized for BNS
Pha_SR = 0.15
BNS = 142 MpcBBH = 1100 Mpc
5252
108 ly
Enhanced LIGO/Virgo+ Virgo/LIGO
Credit: R.Powell, B.Berger
Adv. Virgo/Adv. LIGO
2nd generation detectors– BNS inspiral range >10x
better than Virgo– Detection rate: ~1000x better
– 1 day of Adv data ≈ 3 yrs of data
2nd generation network. – Timeline: commissioning to
start in 2014.
Advanced detectors
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Advanced Virgo
• On December 4 EGO, the Consortium owned by CNRS and INFN, approved the Advanced Virgo Project
• Significant financial commitments already in 2009• Work in short term: optical scheme, light source, plan on
how to provide early new data to the community
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Motivation for a Global GW Detector Network
LIGOGEO VIRGO TAMA
AIGO
t1
t2
t3 t5
t4
t6
• Time-of-flight to reconstruct source position
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Motivation for a Global GW Detector Network
source location
• Source location: – Ability to triangulate (or ‘N-angulate’) and more accurately pinpoint source
locations in the sky– More detectors provides better source localization Multi-messenger
astronomy
• Network Sky Coverage:– GW interferometers have a limited antenna pattern; a globally distributed
network allows for maximal sky coverage
• Detection confidence: – Redundancy – signals in multiple detectors
• Maximum Time Coverage - ‘Always listening’: – Ability to be ‘on the air’ with one or more detectors
• Source parameter estimation:– More accurate estimates of amplitude and phase– Polarization - array of oriented detectors is sensitive to two polarizations
• Coherent analysis: – Combining data streams coherently leads to better sensitivity ‘digging
deeper into the noise’– Also, optimal waveform and coordinate reconstruction
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The Future – LCGT (Japan)
• Based on the long experience of TAMA 300 on Mitaka Campus at NAO• Large-scale Cryogenic Gravitational Wave Telescope – 3 km long next generation interferometer
– Use of cryogenic cooling of test masses to reduce thermal noise in the ‘sweet spot’ of the detector– Located underground in Kamioka mine to reduce seismic noise coupling to test masses
• Prototype - Cryogenic Laser Interferometer Observatory (CLIO) currently in operation in Kamioka mine
– Testbed for development of seismic isolation and cryogenic technologies
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The Future – AIGO (Australia)
• A comparably sensitive detector in Australia will bring increased angular sensitivity and better sky coverage
• Australian Interferometer Gravitational- wave Observatory conceived as a 5 km interferometer
– will follow the AdvLIGO design• Possible variation in suspension and seismic isolation system• Likely location in Western Australia
– Aim for operation in 2017• 2 year lag behind AdvLIGO
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Perspectives for third generation
• Sources are waiting– Systems at cosmological distance– High statistics in binary systems (inspiral waveforms, matter
distribution)– Increased sensitivity in merge and ringdown phase (GR, EOS)– Increased number of pulsars (EOS, population, )– Stochastic background (cosmological and astrophysical)– Coincidences with and X-ray satellites, observatories, …
(system dynamics)
• Gaining another factor 10 in sensitivity• Extending frequency down to a few Hz• Extending further frequency spectrum spectrum
– Pulsar timing– High frequency gravitational waves