Search for Gravitational Wave Transients Florent Robinet On behalf - PowerPoint PPT Presentation

Search for Gravitational Wave Transients Florent Robinet On behalf of the LSC and Virgo Collaborations Rencontres de Moriond - March 2011 1

Gravitational Waves Gravitational Waves Gravitational waves = "ripples" in space-time = "ripples" in space-time Gravitational waves g  =   h  ∣ h  ∣≪ 1 Weak field approximation : Weak field approximation : c Wave equation, speed c Wave equation, speed h = h +  h x Solution with 2 d.o.f. : Solution with 2 d.o.f. : Dimensionless amplitude given by h h Dimensionless amplitude given by h rss =  ∫ - ∞ + ∞ 2 ∣ h x  t ∣ 2  dt Black hole merger ∣ h +  t ∣ Signal strength: Signal strength: Production of gravitational waves 2  R  2  c  6 R s 5 c v ℒ = G  A good GW source : – 39 Lab production : h ~ 10 – 39 Lab production : h ~ 10 - is compact and massive - is asymmetric Astrophysical sources : h ~ 10 h ~ 10 – 21 – 21 Astrophysical sources : - has a relativistic speed Rencontres de Moriond - March 2011 2 Florent Robinet

Gravitational Wave Sources Gravitational Wave Sources Supernovae Pulsars (asymmetric core (asymmetric rotations, bounce) instabilities) Compact binary coalescence of neutron stars &/or black holes Cosmic strings ? The unexpected Stochastic background Rencontres de Moriond - March 2011 3 Florent Robinet

A Network of Detectors A Network of Detectors LSC – Virgo collaboration Virgo (3 km) – Full data sharing since May 2007 – Common analyses and papers – Common tools Livingston (4 km) Geo (600 m) Hanford (4&2 km) Rencontres de Moriond - March 2011 4 Florent Robinet

A Network of Detectors A Network of Detectors SOURCE POINTING ● Source location within ~ tens of square degrees ● Serious candidates follow-up (EM, neutrinos...) t Virgo SOURCE t Livingston GHOST t Hanford t Hanford Rencontres de Moriond - March 2011 5 Florent Robinet

A Network of Detectors A Network of Detectors Hanford sky coverage – Antenna pattern Rencontres de Moriond - March 2011 6 Florent Robinet

A Network of Detectors A Network of Detectors Livingstone sky coverage – Antenna pattern Rencontres de Moriond - March 2011 7 Florent Robinet

A Network of Detectors A Network of Detectors Virgo sky coverage – Antenna pattern Rencontres de Moriond - March 2011 8 Florent Robinet

A Network of Detectors A Network of Detectors Network sky coverage – Antenna pattern Rencontres de Moriond - March 2011 9 Florent Robinet

LIGO / Virgo Science Runs LIGO / Virgo Science Runs 2005 2006 2007 2008 2009 2010 2011 2012 commissioning S4 S5 S6 Advanced Detectors VSR1 VSR2 VSR3 VSR4? Many Publications Analyses in progress Publications in preparation Rencontres de Moriond - March 2011 10 Florent Robinet

LIGO / Virgo Science Runs LIGO / Virgo Science Runs S6 - VSR2 S5 - VSR1 Rencontres de Moriond - March 2011 11 Florent Robinet

Analysis Groups Analysis Groups ? Compact Binary Coalescence Short Signals Continuous Waves Stochastic (Bursts) (CBC) See C. Palomba's talk Rencontres de Moriond - March 2011 12 Florent Robinet

Analysis Groups Analysis Groups ? Compact Binary Coalescence Short Signals (Bursts) (CBC) Low Mass High Mass All sky Multi-Messenger GRB-triggered Astronomy Parameter Inspiral-Merger- Supernovae Estimation Ringdown (IMR) SGR Flares Pulsars Glitches EM Follow-up Binary Mergers Cosmic Strings Rencontres de Moriond - March 2011 Florent Robinet

CBC vs. Bursts CBC vs. Bursts Burst Signals Compact Binary Coalescence (CBC) The Signals The Signals ● Modeled signals ● Short-duration signals (<1s) ● Inspiral – Merger – Ringdown ● Modeled and unmodeled signals ● Large variety of sources The search The search ● Template search (selective) ● Robust signal detection methods ● Waveform parameter estimation ● Excess power (unmodeled) ● Template search (modeled) Science goals Science goals ● Detection ● Detection ● Upper limits on GW emission ● Upper limits on GW emission ● Multi-messenger (EM, neutrino...) ● Multi-messenger (EM, neutrino...) ● Parameter estimation ● Parameter estimation ● Study gravity ● Star equation of state ● Study populations ● Study populations ● Study dense matter ● Study GRBs Rencontres de Moriond - March 2011 14 Florent Robinet

Analysis Methods Analysis Methods COINCIDENT PIPELINE Selection Data Detector 1 Triggers + Coincidence Significance? Data Data Detector 2 Triggers Quality Data stream Rencontres de Moriond - March 2011 15 Florent Robinet

Analysis Methods Analysis Methods COINCIDENT PIPELINE Selection Data Detector 1 Triggers Significance + Coincidence wrt Data background Data Detector 2 Triggers Quality DETECTION? Data Detector 2 Data stream NO? time-shifted wrt 1 → Upper limits Background stream Rencontres de Moriond - March 2011 16 Florent Robinet

Analysis Methods Analysis Methods COINCIDENT PIPELINE UPPER LIMITS Signal injections Search efficiency Selection Data Detector 1 Triggers Significance + Coincidence wrt Data background Data Detector 2 Triggers Quality DETECTION? Data Detector 2 Data stream time-shifted wrt 1 Injection stream Background stream The number of detectors can be increased (up to 4) Various coincidence schemes: union of configurations Increasing the number of coincidences enables to be more selective (but less efficient) Rencontres de Moriond - March 2011 17 Florent Robinet

Analysis Methods Analysis Methods COHERENT PIPELINE UPPER LIMITS Signal injections Search efficiency Selection Data Detector 1 Significance Coherent + Triggers wrt combination Data background Data Detector 2 Quality DETECTION? Data Detector 2 Data stream time-shifted wrt 1 Injection stream Background stream The data of multiple detectors can be combined coherently Sky positions are scanned to take into account the time of arrival and the antenna pattern of each detectors Rencontres de Moriond - March 2011 18 Florent Robinet

Analysis Methods: Template Searches Analysis Methods: Template Searches Signal-to-noise ratio time serie: Detector whitened Strain h(t) ∞ h  f  f  Noise + inspiral hardware injection − 2i  f t df  t ∝ ∫ e S h  f  0  Template waveform S h Sensitivity  t  Threshold An event is defined when Given by the background estimation (+ additional clustering in time and frequency) This method is used for: ● CBC searches ● Pulsar ringdown search ● Cosmic string burst search A template bank covering the parameter space is slid over the data Rencontres de Moriond - March 2011 19 Florent Robinet

Analysis Methods: Excess Power Searches Analysis Methods: Excess Power Searches Injected Inspiral Signal The time-frequency plane is tiled with pixels An event is defined when the energy of multiple pixels exceeds a given threshold This method is used for: ● Most of the burst searches Rencontres de Moriond - March 2011 20 Florent Robinet

Data Quality Data Quality The noise of the detector displays a non- Detection channel Gaussian behavior Transient glitches removal is crucial to Magnetic sensor improve the sensitivity of the searches Noise understanding for each detector Example: Virgo, VSR2 have been performed for each science run Deadtime ~ 10% Removal efficiency ~ 80% (SNR>8) Many glitch families have been understood Specific vetoes based on auxiliary channels have been produced to remove specific glitch families Veto safety have been carefully checked (we don't want to flag real signals!) 10 100 SNR Rencontres de Moriond - March 2011 21 Florent Robinet

CBC Searches CBC Searches BNS BBH BHNS S5/VSR1 data have been analyzed and results are published "Realistic" observable BNS coalescence rate S6/VSR2-3 analyses are in ~ 0.02 per year (large uncertainty) progress Preliminary results are released See T. Dent's talk Rencontres de Moriond - March 2011 22 Florent Robinet

CBC: Low Mass Search CBC: Low Mass Search Description of the search: No Detection ● Non-spinning templates ● Post-Newtonian up to the innermost stable orbit ● Mass region 2 < M total < 35 M sun Phys. Rev. D 82(2010) 102001 NS/BH Upper limits BNS/BBH Upper limits Rencontres de Moriond - March 2011 23 Florent Robinet

CBC: High Mass Searches CBC: High Mass Searches High-Mass ● Effective One Body (EOB) waveforms ● Inspiral-Merger-Ringdown is covered ● No spin ● Mass region 25 < M total < 100 M sun ● Uncertainty on the waveforms ● LIGO only search (Virgo is not sensitive enough for High mass systems) Ringdown search ● In progress for S5 ● LIGO only search ● Mass region 75 < M BH < 750 M sun ● Spin is included ● The ringdown contains arXiv:1102.3781 most of the GW energy ● More reliable waveforms Rencontres de Moriond - March 2011 24 Florent Robinet