Recent Virgo/LIGO Results And Future Prospects Florent Robinet - - PowerPoint PPT Presentation

▶
recent virgo ligo results and future prospects
SMART_READER_LITE
LIVE PREVIEW

Recent Virgo/LIGO Results And Future Prospects Florent Robinet - - PowerPoint PPT Presentation

Oct 17, 2022 229 likes •540 views

LIGO-G0900655-v3 Recent Virgo/LIGO Results And Future Prospects Florent Robinet Journes SF2A, July 2009 Florent Robinet Gravitational Waves Gravitational waves = "ripples" in space-time They obey a wave equation - propagation

slide-1
SLIDE 1

Recent Virgo/LIGO Results And Future Prospects

Florent Robinet

LIGO-G0900655-v3 Journées SF2A, July 2009 Florent Robinet

slide-2
SLIDE 2

Gravitational Waves

Gravitational waves = "ripples" in space-time They obey a wave equation

  • propagation speed = c
  • two transverse polarizations ( + and x )

Dimensionless amplitude given by h Production of gravitational waves A good GW source :

  • is compact and massive
  • is asymmetric
  • has a relativistic speed

c

5

G 

2

Rs R 

2

v c 

6

Lab production 2 one-ton masses, 2 m apart, rotating at 1kHz Looking at a distance of 1 (~300 km) : h~10-39 Not even a chance ! Astronomical sources h~10-21 Worth a try...

Journées SF2A, July 2009 Florent Robinet

ℒ =

slide-3
SLIDE 3

Sources of Gravitational Waves

Supernovae Compact Binary Systems (Black holes / Neutron stars ) Pulsars Stochastic background Cosmic strings

?

Unexpected

Journées SF2A, July 2009 Florent Robinet

slide-4
SLIDE 4

Detection of Gravitational Waves L L L+L L-L

free mass Beam splitter free mass laser photodiode

GW

h~ L L  L~10

−18 m

Journées SF2A, July 2009 Florent Robinet

slide-5
SLIDE 5

Detection of Gravitational Waves L L L+L L-L

free mass Beam splitter free mass laser photodiode

GW

h~ L L  L~10

−18 m

Main Sensitivity factors :

  • Arm length  high finesse Fabry-Perot cavity
  • Laser power
  • Mechanical and thermal stability of the free

masses  suspensions, coating...

Journées SF2A, July 2009 Florent Robinet

slide-6
SLIDE 6

The Virgo Interferometer

History 1989 : proposal 1992 : french approval 1996 : construction starts 2001 : tests on the central itf 2003 : commissioning starts 2007 : first science run (VSR1) 2nd Science Run 7th of July 2009  … : VSR2 1st Science Run : May  Oct 2007 : VSR1 Duty cycle = 81% Long locks (up to 94h) Range for a 1.4-1.4 M⊙ system : ~4Mpc Characteristics Located in Italy (Pisa) 3 km long arms Cavity finesse : 50

Journées SF2A, July 2009 Florent Robinet

slide-7
SLIDE 7

The Virgo Sensitivity

Sensitivity improvements

Journées SF2A, July 2009 Florent Robinet

slide-8
SLIDE 8

The Virgo Noise budget

Noise budget

Journées SF2A, July 2009 Florent Robinet

Sum of modeled noise Measured sensitivity

slide-9
SLIDE 9

Detectors Network

Virgo (3 km) Geo (600 m) Livingston (4 km) Hanford (4&2 km)

LSC – Virgo collaboration Full data sharing since May 2007

Journées SF2A, July 2009 Florent Robinet

slide-10
SLIDE 10

Detectors Network

Livingston

S5 / VSR1 S6 / VSR2

Coincidence between detectors → Reduction of the false alarm rate → Background estimation Virgo Hanford 2 Hanford 1

Journées SF2A, July 2009 Florent Robinet

Livingston Virgo Hanford 1

slide-11
SLIDE 11

Detectors Network

tLivingston tHanford tHanford tVirgo SOURCE SOURCE POINTING

  • Source location within a few degrees
  • Serious candidates follow-up (EM, neutrinos...)

GHOST

Journées SF2A, July 2009 Florent Robinet

slide-12
SLIDE 12

Searches for GW Signals

whitened data

Data = stream of noise Parameterized waveforms (template bank) are searched in the data : Matching template/data  Signal-to-noise ratio (SNR) Ideally : high SNR events = GW events BUT : real data have glitches  non-Gaussian noise Search strategies :

  • Use of clean data (data quality studies)
  • Coincidence in time and parameters between detectors
  • Target search in space and time (GRBs, pulsars...)
  • Additional cuts (2, mass, amplitude...)
  • Background estimation (time-offset between detectors or
  • ff-source time)
  • Search efficiency computed thanks to hardware and

software injections

Templates

Journées SF2A, July 2009 Florent Robinet

slide-13
SLIDE 13

Searches for GW Signals

Characteristics :

  • BH-BH, NS-NS or BH-NS systems
  • VSR1 range ~ 4 Mpc (NS-NS, 1.4-1.4 M⊙, SNR=8)
  • Total mass < 500 M⊙
  • Waveforms computed in the general relativity framework
  • Free parameters : mass, spin and orbits
  • Inspiral / Merger / Ringdown phases

Compact Binary Coalescence

Can provide information about :

  • Strong field gravity
  • Dense matter
  • Population of massive bodies in the universe
  • Cosmology (standard candles)
  • Sources of GRB
  • Astrophysics of the source

Inspiral Merger Ringdown

3 mass regions :

  • "Low mass" ( 2 < M < 35 M⊙) : Post-Newtonian waveforms
  • "High mass" ( 25 < M < 100 M⊙) : IMR waveforms
  • "Black holes ringdown" ( M < 500 M⊙) : Damped sinusoid

Journées SF2A, July 2009 Florent Robinet

slide-14
SLIDE 14

Searches for GW Signals

Sources

  • Supernovae core collapse
  • Merger / ringdown of binary compact objects
  • Neutron stars instabilities
  • Cosmic string cusps
  • Unexpected signals...

Burst Signals, see also talk by M. Was

Characteristics :

  • Short lived signals (~1 ms ⇒ ~1 s)
  • Broad-band search : ~50 Hz to a few kHz
  • Unknown or poorly known waveforms
  • Minimal or no assumption about the waveforms
  • Search open to the unexpected
  • Multiple analysis pipelines

Dimmelmeier et al., astro-ph/0702305

Journées SF2A, July 2009 Florent Robinet

slide-15
SLIDE 15

Searches for GW Signals

Continuous Signals

Stochastic Background Signal :

  • Early Universe GW Background ( ~ CMB)
  • Integrated signal
  • Constraints on GW.

S5 preliminary result :  GW < (1.0 ± 5.2)10-6 (it surpasses the Big-Bang nucleosynthesis bound) Pulsar Signals :

  • Targeted search (~ 200 known pulsars w/ fspin > 20 Hz)
  • Integrated signal (targeted search :

, all-sky : )

  • Assumption fGW = 2 fspin

Can provide information about :

  • Ellipticity
  • Solid quark star ?
  • Internal magnetic field ?
  • Energy budget of the star spin-down

Journées SF2A, July 2009 Florent Robinet

snr~t

1/2

snr~t

1/4

slide-16
SLIDE 16

Recent Highlights

Isotropic detection efficiency SG rates vs. strength exclusion curves Search for gravitational wave bursts in S5 LIGO runs

Journées SF2A, July 2009 Florent Robinet

slide-17
SLIDE 17

Recent Highlights

1.4 x 10-2 L10

  • 1 yr-1

5.0 x 10-4 L10

  • 1 yr-1

5.0 x 10-5 L10

  • 1 yr-1

3.6 x 10-3 L10

  • 1 yr-1

6.0 x 10-5 L10

  • 1 yr-1

2.0 x 10-6 L10

  • 1 yr-1

7.3 x 10-4 L10

  • 1 yr-1

6.0 x 10-5 L10

  • 1 yr-1

4.0 x 10-7 L10

  • 1 yr-1

Search for gravitational waves from low mass compact binary coalescence (S5)

  • S5/VSR1 under internal review
  • High mass under internal review
  • BH ringdown : in progress

Journées SF2A, July 2009 Florent Robinet

slide-18
SLIDE 18

Recent Highlights

  • Upper limit on the Crab pulsar :

Energy loss by GW radiation < 2%

  • Upper limit for J0537-6910 :

h0 < 4.4 10-26  < 1.3 10-4

  • Upper limit for J1952+3252 :

h0 < 2.9 10-25  < 2.7 10-4 Virgo should contribute significantly at low frequency (Vela pulsar) Search for gravitational waves produced by pulsars (S5)

Journées SF2A, July 2009 Florent Robinet

slide-19
SLIDE 19

Recent Highlights

Search for gravitational waves produced by cosmic strings cusps (S4) S5 / VSR1 analysis is on-going It should set competitive limits

  • ver the parameter space

Excluded @ 90%

Journées SF2A, July 2009 Florent Robinet

slide-20
SLIDE 20

Recent Papers

7 Papers were submitted/published in the last 3 months

  • Search for gravitational-wave bursts in the first year of the fifth LIGO science run
  • Stacked Search for Gravitational Waves from the 2006 SGR 1900+14 Storm
  • Search for High Frequency Gravitational Wave Bursts in the First Calendar Year of LIGO's Fifth Science Run
  • First LIGO search for gravitational wave bursts from cosmic (super)strings
  • Search for gravitational wave ringdowns from perturbed black holes in LIGO S4 data
  • Einstein@Home search for periodic gravitational waves in early S5 LIGO data
  • Search for Gravitational Waves from Low Mass Compact Binary Coalescence in 186 Days of LIGO's fifth Science Run

+ Papers on the joint LSC-Virgo search are to come

Journées SF2A, July 2009 Florent Robinet

slide-21
SLIDE 21

A Path to Detection

2003 Virgo starts commissioning 2005 LIGO reaches nominal sensitivity

S4 S5 VSR1 S6 VSR2 C7

TODAY

2008-2009 Virgo+ and eLIGO upgrades

VSR2

2009-2011 Joint Run S6-VSR2

1st GENERATION Unlikely Could be... DETECTION

Journées SF2A, July 2009 Florent Robinet

slide-22
SLIDE 22

S6 / VSR2 Preparation

Virgo upgrades (Virgo+) :

  • Same infrastructure
  • Increase the laser power (from 8 to 17 W today and to 25 W eventually)
  • Thermal Compensation System (TCS) of the mirrors
  • New input mode cleaner
  • New control electronics
  • New mirrors for a higher cavity finesse (next year)
  • Monolithic suspension (next year)

Gain in sensitivity

Journées SF2A, July 2009 Florent Robinet

TCS

slide-23
SLIDE 23

S6 / VSR2 Preparation

VIRGO

Commissioning efforts to reach design sensitivities

Journées SF2A, July 2009 Florent Robinet

Used to be ~ 4 Mpc (S5/VSR1) VIRGO

slide-24
SLIDE 24

S6 / VSR2 Preparation

Online Analysis :

  • Bursts and CBC analysis pipelines are run online (latency < 1 h)
  • Data of the 3 detectors are put in coincidence
  • Source direction is extracted
  • False alarm rate can be tuned
  • Data quality is monitored
  • Hardware injections are performed
  • Crucial factors : low latency, good pointing accuracy, low false alarm rate
  • Low latency triggered searches (GRB, SN...)
  • Follow-up of best candidates at other astronomical observatories

Optical : Wide field, Radio, X-ray (Swift, TAROT...) Neutrinos detectors : (Super-K, Antares, IceCube...) ⇒ T. Pradier's talk

Trigger spectrogram

SNR > 5 SNR > 10 SNR > 20 Journées SF2A, July 2009 Florent Robinet

TAROT

slide-25
SLIDE 25

A Path to Detection

2003 Virgo starts commissioning

S4 S5 VSR1 S6 VSR2 C7

TODAY

2008-2009 Virgo+ and eLIGO upgrades 2011-2014 Advanced Virgo and LIGO Installation-Commissioning

VSR2

2009-2011 Joint Run S6-VSR2 2014-20?? First run with advanced detectors

1st GENERATION 2nd GENERATION 3rd GENERATION

2018-20?? GW astronomy (Einstein Telescope...)

Unlikely Could be... Probably GW astronomy DETECTION

2005 LIGO reaches nominal sensitivity

Journées SF2A, July 2009 Florent Robinet

slide-26
SLIDE 26

Advanced Virgo

Advanced Virgo :

  • High laser power (125 W)
  • Monolithic suspension
  • New mirrors, larger beam
  • High finesse cavity (from 50 to 900)
  • Signal recycling

Challenges

Good quality and stable beam Good thermal dissipation in the suspensions (fused silica) Mirror thermal noise (new material and coating) Lock acquisition of the high finesse cavity (CALVA prototype @ LAL) Modulator and Faraday isolators able to cope with a 125 W power Faster electronics

Journées SF2A, July 2009 Florent Robinet

slide-27
SLIDE 27

Journées SF2A, July 2009 Florent Robinet

Advanced Virgo

slide-28
SLIDE 28

Binary neutron star coalescence Black hole - neutron star coalescence Binary black hole coalescence

Journées SF2A, July 2009 Florent Robinet

Advanced Virgo

The Advanced Virgo project is on the way and should start taking data (along with Advanced LIGO) by 2014-2015

slide-29
SLIDE 29

Conclusions

Journées SF2A, July 2009 Florent Robinet

  • 1st generation detectors have taken data at design sensitivity
  • No detection yet. Efforts are made to make it happen !
  • S5 papers have been released/published a few months ago (upper limits).

S5/VSR1 papers are to come soon

  • The start of S6/VSR2 is imminent (7th of July). Many new features/improvements

increased sensitivity - online analysis – source pointing – external follow-up

  • Advanced detectors are on the way (2014) : milestones to future GW astronomy