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First generation GW interferometers: main results

First generation GW interferometers: main results. Sergio Frasca Sapienza University and INFN, Rome Beijing, October 2011. The 1 st generation interferometers mission has ended. Last scientific data were taken on 05-Sep-2011 Next: 2 nd generation: Ligo and Virgo “Advanced” ( 2015)

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First generation GW interferometers: main results

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  1. First generation GW interferometers: main results Sergio Frasca Sapienza University and INFN, Rome Beijing, October 2011

  2. The 1st generation interferometers mission has ended • Last scientific data were taken on 05-Sep-2011 • Next: • 2nd generation: Ligo and Virgo “Advanced” (2015) • 3rd generation: LCGT (2017), Einstein telescope (>2020) • In this talk I present some glimpses on the main published results up to now, as an invitation to read the full papers.

  3. Summary • The end of the first generation interferometers • The antennas and the data • The main experimental results • The data analysis is not finished

  4. The LIGO antennas Livingston (LA) Hanford (WA)

  5. The Virgo antenna Cascina (Tuscany)

  6. Geo (600 m) and Tama (300 m)

  7. The MOU The Ligo-Virgo Memorandum of Understanding (2007) “All gravitational wave data analysis will be carried out under the umbrella of this agreement between LIGO and VIRGO; there will be no LSC-only or Virgo-only gravitational wave data analyses while this agreement remains in force.”

  8. The last Science runs

  9. The sensitivity

  10. The development of the Virgo sensitivity

  11. The signals • Burst (supernova explosion, magnetars giant flares,…) • Chirp (CBC – Compact binary coalescence) • Periodic (rotating neutron stars) • Stochastic (cosmological GW background)

  12. Main recent data analysis papers • Beating the spin-down limit on gravitational wave emission from the Vela pulsar, The Astrophysical Journal, 737:93 (16pp), 2011 August 20 • Very Low Latency Search for Low Mass Compact Binary Coalescences, in the LIGO S6 and Virgo VSR2 Data GWDAW14 proceedings • Search for gravitational waves from black hole binary inspiral, merger and ringdown, Phys. Rev. D 83, 122005 (2011) • Search for Gravitational Waves from Compact Binary Coalescence in LIGO and Virgo Data from S5 and VSR1,Phys. Rev D82, 102001 (2010) • SEARCH FOR GRAVITATIONAL-WAVE INSPIRAL SIGNALS ASSOCIATED WITH SHORT GAMMA-RAY BURSTS DURING LIGO'S FIFTH AND VIRGO'S FIRST SCIENCE RUN, The Astrophysical Journal, 715:1453–1461, 2010 June 1 • All-sky search for gravitational-wave bursts in the first joint LIGO-GEO-Virgo run, Phys. Rev. D 81, 102001 (2010) • An upper limit on the stochastic gravitational-wave background of cosmological origin, Nature, Vol 460|20 August 2009| • SEARCH FOR GRAVITATIONAL-WAVE BURSTS ASSOCIATED WITH GAMMA-RAY BURSTS USING DATA FROM LIGO SCIENCE RUN 5 AND VIRGO SCIENCE RUN 1,The Astrophysical Journal, 715:1438–1452, 2010 June 1 • SEARCHES FOR GRAVITATIONAL WAVES FROM KNOWN PULSARS WITH SCIENCE RUN 5 LIGO DATA, The AstrophysicalJournal 713 (2010) 671-685 More bibliography at the end

  13. Pulses • Unmodeled (short) bursts: • Time-frequency • Wavelet • Coincidences with GRBs • All-sky search

  14. All sky search for GW bursts in S5 and VSR1 • Results from an all-sky search for unmodeled gravitational-wave bursts in the data collected by the LIGO, GEO 600 and Virgo detectors between November 2006 and October 2007 are presented. • The search is performed by three different analysis algorithms over the frequency band 50–6000 Hz. Data are analyzed for times with at least two of the four LIGO-Virgo detectors in coincident operation, with a total live time of 266 days. • No events produced by the search algorithms survive the selection cuts. • A frequentist upper limit on the rate of gravitational-wave bursts impinging on our network of detectors was set. When combined with the previous LIGO search of the data collected between November 2005 and November 2006, the upper limit on the rate of detectable gravitational-wave bursts in the 64–2048 Hz band is 2.0 events per year at 90% confidence. • This is the first untriggered burst search to use data from the LIGO and Virgo detectors together, and the most sensitive untriggered burst search performed so far.

  15. Chirps S6 & VSR2 (optimal orientation)

  16. Chirps – S5 upper limit • The first modeled search for gravitational waves using the complete binary black-hole gravitational waveform from inspiral through the merger and ringdown for binaries with negligible component spin has been presented. • Approximately 2 years of LIGO data, taken between November 2005 and September 2007, for systems with component masses of 1–99 Mₒ and total masses of 25–100 Mₒ have been analyzed. • No plausible gravitational-wave signals was detected, but upper limits on the merger rate of binary black holes as a function of the component masses in this range have been put. • The rate of mergers for 19 Mₒ< m1, m2 < 28 Mₒ binary black-hole systems with negligible spin has been constrained to be no more than 2.0 Mpc-3 Myr-1at 90% confidence.

  17. The trigger for telescopes and the Swift satellite • A transient astrophysical event observed in both gravitational wave (GW) and electromagnetic (EM) channels would yield rich scientific rewards. • A first program initiating EM follow-ups to possible transient GW events has been developed and exercised by the LIGO and Virgo community in association with several partners. • The methods used to promptly identify and localize GW event candidates and to request images of targeted sky locations have been evaluated by a simulation. • It was actually applied during the last part of S6 and VSR3.

  18. The “Big Dog” event • To check the capacity of the collaboration data analysis chirp and bursts pipelines, a procedure of signal “blind injection” to all the three antennas was set up. When this is done (by a small group of people), the injection data are put in a sealed envelope, and no notice is given to the collaboration (that knows only that a blind injection can be present in the run). • On 16 September 2010, during the night, we got a signal in the three antennas, well above our background. • In the online data analysis it was well detected and the telescopes were pointed, but no electromagnetic counterpart was detected. • Then started a deep discussion inside the group about the detected event, to exclude artifacts and disturbances, or erroneous probability evaluations. • At the end we wrote a paper claiming detection. • The collaborations voted to publish. • Then, on 14 March 2011, the envelope was opened and we learned it was a blind injection.

  19. Periodic waves • Known pulsar (117 pulsars, particularly Crab and Vela) • Known position (Cas A, GC, SN1987A in LMC, some globular clusters) • Periodic in binary or complex systems (Sco X1) • Blind search (all sky) • Einstein@Home (big cluster of (mainly) home computers)

  20. Known Pulsars • 116 pulsars, S5 data • Crab upper limit 2 % in energy of the spin-down limit. Ellipticity limit: 1.0 10-4 • J0537-6910 at spin-down limit

  21. Vela pulsar • Data from Virgo VSR2 (about 6 months) • 3 different pipelines: • Heterodyne (restricted and unrestricted prior) • F and G statistics • Matched filter on 5 Fourier components (2 and 4 d.o.f.) • 35 % in power of the spin-down limit has been reached • Upper limit on ellipticity: 1.1 10-3

  22. The Vela killer chiller The Vela VSR2 low-resolution power spectrum

  23. Known position: CasA supernova remnant • 12 days of S5 data used • Coherent search with f-statistics. • Frequency band 100-300 Hz. • Wide range of first and second derivative considered.

  24. All sky search“Powerflux” • On full S5 data Evaluatedamplitude Evaluated spin-down

  25. All sky search“Sky Hough” • Semi-coherent search (hierarchical), based on Sky Hough algorithm • First and second S5 years analyzed separately. Coincidences between candidates • Justify or follow up coincident candidates is in progress

  26. Frequency Time SkyHough • Use of the Hough transform from the space of the time/frequency to the space of the sky coordinates (typically ecliptical

  27. Hough map – source reconstruction For every peak, we compute the annulus and enhance by one the relative pixels of the sky map. Doing the same for all the peaks, we have a two-dimension histogram, with one big peak at the position of the source. Normally, because the motion of the detector that has a big component on the ecliptical plane, there is also a “shadow” false peak, symmetrical respect this plane.

  28. FrequencyHough In this new procedure the transformisdonebetween the plane time/frequency and the planefrequency/frequency derivative. There are some advantages on artifactsanalysis, computationalspeed, and lowerloss in digitization.

  29. All sky search“PSS Frequency Hough” • Plans: full analysis of VSR2 and VSR4 data , starting from the low frequency band, where the Virgo has a competitive sensitivity.

  30. Einstein@Homehttp://einstein.phys.uwm.edu/ • Similarly to SETI@home, Einstein@Home is a volunteer distributed computing project hosted by the University of Wisconsin–Milwaukee and the Max Planck Institute for Gravitational Physics (Albert Einstein Institute, Hannover, Germany) • As of September 2011, over 300,000 volunteers in 221 countries have participated in the project • The most recent published analysis is on 840 hours of Ligo S5 data • No statistically significant signals were found • The Einstein@Home at home super-cluster was used also to analyze radio-telescope data. Two new pulsars have been detected.

  31. Stochastic background • Isotropy (two algorithms, the first with two signal models)

  32. Stochastic background • Ω upper limit

  33. What’s next • The next GW detectors step will be, presumably in 2015, the start of the 2nd generation interferometers with improvements in sensitivity and bandwidth.

  34. Conclusions • To complete the analyses on 1st generation GW interferometer data and publish the data, we need at least other two years. • These may give still good surprises.

  35. Bibliography – full reference • https://www.lsc-group.phys.uwm.edu/ppcomm/Papers.html • https://www.ego-gw.it/editorialboard/list.aspx

  36. Papers presented at Amaldi 9Cardiff July 2011 http://www.amaldi9.org • Results of Recent GW Transient Searches • Search for Gravitational Waves from Intermediate Mass Binary Black Holes • CW searchresults • Searching for gravitational Waves from the Vela Pulsar in Virgo VSR2 data • A Modelled Cross-Correlation Search for ScorpiusX-1 • Multi-baseline gravitational wave radiometry for searching stochastic sources with advanced detectors

  37. My first visit to BeijingAugust 1982 Thank you for your kind hospitality

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