The VIRGO Project and theGravitational Wave Network on the ground

Stefano Braccini

INFN Pisa

e-mail: stefano.braccini@pi.infn.it

1) Introduction

2) Working Principle

3) Status of VIRGO

4) Interferometer Network

5) The Future

2

hLL

L m

h

(VIRGO Supernova)

L m

L-L

L+L

t = 0 t = /4 t = t = 3/4 t = T

Interferometric Detection

Sources

NS or BHCoalescing Binaries

chirp

Signals can be exactly computed(except for final part)

Time

h

Hz kHz…minutes…

Pulse of ms duration(no template available)

Sources

Supernova Bursts

Sources

SNR can be increased by integrating the signal for long time (months)

6

2

24527

10Hz 200g/cm 10

kpc 10103

fI

rh

Emits periodic signals at f=2fspin but ….weak

Importance of a low frequency sensitivity (Hz region)

Neutron Stars

Wide variety of signals expected betweenfraction of Hz and a few kHz

1) Introduction

2) Working Principle

3) Status of VIRGO

4) Interferometer Network

5) The Future

A simple detector

h = 10-21 gw= 3·10-11 rad)(4

)( thLt

Fabry-Perot Cavities to increase the effect

Increase beam phase shift by 2F

Optical Readout Noise

2 1 shot shot

ch

P L P

20 W 1 kW

An accurate measurement of the phaserequires a large amount of photons…

• Fluctuation-dissipation theorem

Thermal Noise

)(4)(~2 fTkfF B

Reduce dissipations in the optical payload

Seismic Noise

Strong vibration filtering by a chain of mechanical low frequency oscillators

in 6 dof

frequency

Tra

nsm

issi

on

Summary of the technique

Low Dissipations SeismicAttenuation

Fabry-Perot

Vacuum

photodiodeRecycling

High Power Laser

What is a sensitivity curve ?

Thermal Shot

Seismic

Advanced resonant

SPACEGROUND

Ground and Space are complementary

Ground-Based Network

TAMA600 m

300 m4 & 2 km

4 km

AIGO

3 km

1) Introduction

2) Working Principle

3) Status of VIRGO

4) Interferometer Network

5) The Future

VIRGO• LAPP – Annecy

• INFN – Firenze-Urbino

• INFN – Frascati

• IPN – Lyon

• INFN – Napoli

• OCA – Nice

• LAL – Orsay

• ESPCI – Paris

• INFN – Perugia

• INFN – Pisa

• INFN – Roma

VIRGO at EGO Site

VIRGO Optical Scheme

Laser 20 W

Input Mode Cleaner (144 m)

Output Mode

Cleaner (4 cm)

3 km long Fabry-Perot

Cavities

Power

Recycling

Superattenuators

Blade springs

Magnetic antisprings

Extend the band down toa few Hz

Resonance Crossing

Mir

ror

Sur

face

0.5 m/s

MIRRORSWING

Photodiode demodulated signal during resonance crossing

HOOK CAVITIES AT RESONANCE USING MIRROR COIL-MAGNET

ACTUATORS

Interferometer Locking

Quadrants and Photodiodes to close angular and longitudinal feedbacksaimed to keep the VIRGO cavities aligned and at resonance

InterferometerControl

Measure the sensitivity Identify the noise sources Try to reduce the noise

C5 recycled

May 27th, recycled

Reduced Beam Splitter DAC noise

Beam Splitter Control Improvements

Photodiode NoiseReduction

Noise Hunting and Reduction

Virgo Commissioning Runs Sensitivities

Present Status

After a few months long stop (to upgrade the injectionbench) VIRGO restarted the activities on January 06

Long term scientific run with sensitivities similar to LIGO scheduled for September 2006

VIRGO Data Analysis

Agreement for a coherent data analysis withLIGO will be implemented in the next weeks

h Reconstruction

Noise analysis & data quality

Coalescing binaries

Bursts

Periodic sources

Stochastic background

Six working groups settled up inside Virgo since 1998

1) Introduction

2) Working Principle

3) Status of VIRGO

4) Interferometer Network

5) The Future

LIGO

• 3 ITF: Hanford (4 km, 2 km), Livingston (4 km)

• Same optical scheme as VIRGO, simpler suspensions

• Two science runs already performed

LIGO Commissioning

LIGO is in action at the design sensitivity

Long term scientific run (S5) started on November 2005 in order to accumulate 1 year of data

DETECTOR

COALESCING

BINARIES HORIZON

(Max)

Livingston (4 km) 11 Mpc

Hanford 1 (4 km) 14 Mpc

Hanford 2 (2 km) 7 Mpc

DETECTOR

DUTY

CYCLE

Livingston (4 km) 55.1 %

Hanford 1 (4 km) 63.9 %

Hanford 2 (2 km) 72.5 %

Double Coincidence: 66.7% - Triple Coincidence: 38.4 %

Long term scientific run (S5) started on November 2005 in order to accumulate 1 year of data

DETECTOR

DUTY

CYCLE

Livingston (4 km) 55.1 %

Hanford 1 (4 km) 63.9 %

Hanford 2 (2 km) 72.5 %

Duty cycle is increasing……

Long term scientific run (S5) started on November 2005 in order to accumulate 1 year of data

Ground-Based Network

TAMA600 m

300 m4 & 2 km

4 km

AIGO

3 km

LONG TERM RUN IS STARTING

600 m

1) Introduction

2) Working Principle

3) Status of VIRGO

4) Interferometer Network

5) The Future

10-24

10-23

10-22

10-21

10-20

10-19

10-18

1 10 100 1000 104

h/Hz1/2

Virgo

2006-2007 Network

LIGO

Resonant Antennas 2007

Hz

GEO

Core Collapse@ 10 Mpc

BH-BH MergerOscillations@ 100 Mpc

Pulsarsh

max, 1 year integration

BH-BH Inspiral,z = 0.4

BH-BH Inspiral, 100 Mpc

QNM from BH Collisions, 1000 - 100 Msun, z=1

NS, =10-6 , 10 kpc

QNM from BH Collisions, 100 - 10 Msun, 150 Mpc

NS-NS Inspiral, 300 Mpc

NS-NS MergerOscillations@ 100 Mpc

NS-NS NS-BH BH-BH SNeEvent Rate (per year) 3 10-4 - 0.3 4 10-4 - 0.5 10-3 - 3 0.05Range (Mpc) 30 60 145 0.1

Short Term2006 - 2007 Network

Scarce probability of a first detection

)(~ 2/1Hzh

VIRGO+ and LIGO+

Slight upgradings of the present design (a few months long stops)

Higher laser power (several tens of W)

Monolithic mirror suspensions

Control Noise Reduction

10-24

10-23

10-22

10-21

10-20

10-19

10 100 1000 104Hz

Core Collapse@ 10 Mpc

NS-NS MergerOscillations@ 100 Mpc

BH-BH MergerOscillations@ 100 Mpc

Pulsarsh

max, 1 year integration

h/ĆHz

BH-BH Inspiral,z = 0.4

BH-BH Inspiral, 100 Mpc

QNM from BH Collisions, 1000 - 100 Msun, z=1

NS, =10-6, 10 kpc

QNM from BH Collisions, 100 - 10 Msun, 150 Mpc

NS-NS Inspiral, 300 Mpc

Virgo+

SFERA (Quantum Limit)

2008-2012 Network

DUAL Demonstrator (200 hbar, starting 2011)

GEO HFstarting 2009/2010

LIGO+

NS-NS NS-BH BH-BH SNeEvent Rate (per year) 0.025-10 10-3-15 3 10-2-90 1Range (Mpc) 114 230 584 10

A first detection is likely

Medium Term2008 - 2013 Network

)(~ 2/1Hzh

Advanced LIGO (2013)

Higher power (10 W180 W)

New isolation system (active)

Fused silica suspension wires

40 kg fused silica mirrors

Signal recycling

VIRGO

Similar program for Advanced VIRGO

Next Generation

CERN – C.A.P.P. workshop – June 16th, 2003 G.Losurdo – INFN Firenze-Urbino

LCGT project

Two underground 3 km itfs with mirrors at 20 K in the same vacuum system (Kamioka) – data taking 2012

10-25

10-24

10-23

10-22

10-21

10-20

10 100 1000 104

Advanced Virgo

Hz

Core Collapse@ 10 Mpc

NS-NS MergerOscillations@ 100 Mpc

BH-BH MergerOscillations@ 100 Mpc

SFERA QND

Pulsarsh

max, 1 year integrationLCGT-I

h/ĆHz

3rd Generation ITF

BH-BH Inspiral,z = 0.4

BH-BH Inspiral, 100 Mpc

QNM from BH Collisions, 1000 - 100 Msun, z=1

NS, =10-6, 10 kpc

QNM from BH Collisions, 100 - 10 Msun, 150 Mpc

AdvancedLIGO

NS-NS Inspiral, 300 Mpc

DUAL SiC

2012-2018 Network

SFERA QL

NS-NS NS-BH BH-BH SNeEvent Rate 3/yr - 4/day 1/yr - 6/day 3/month - 30/day 20Range (Mpc) Event300 750 z=0.45 100

…+ LISA (launch 2015)

Long TermBeyond 2013

Detection is “sure”

)(~ 2/1Hzh

NS/NS detectable at 300 Mpc

+ ITFs 2009

Advanced Network2013

VIRGO-LIGO 2006

Virgo

LIGO and VIRGO will perform jointdata analysis, coordinating running,

shutdowns, etc. to maximize GW science

CONCLUSIONS

LIGO long term run in progress (S5)

GEO and VIRGO will join LIGO in this year

FIRST DETECTION UNLIKELY

LIGO+ and VIRGO+ will enter in action after 2008-09

DETECTION LIKELY

Advanced Network (beyond 2013)

GW ASTROPHYSICS

LISA