Francesco Fidecaro

21 dicembre 2009

Risultati e prospettive per la rete LV

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Commissioning: sensitivity progress

25W Virgo+ expected sensitivity128 effective days of data

taking but 0.02 double coincidence event expected

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VSR2 sensitivity for CW searches

Targeted searches.

Vela

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5

5

5

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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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Luce non classica

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Likely rates: 10-4 yr-1 L10-1

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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

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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

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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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Transportation Test

Suspension in the test facility

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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

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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

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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

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Advanced Virgo

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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Perspective

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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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The Future: The Einstein Telescope (Europe)

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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

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Sensitivity future evolution

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Einstein Telescope: time scale