Transcript Document
LIGO data analysis status
Michael Landry
LIGO Hanford Observatory
for the LIGO Scientific Collaboration http://www.ligo.org
PAC19 Dec 12, 2005 LIGO Hanford Observatory
RX J1856.5-3754, neutron or strange quark star at d=117pc Credit: NASA/SAO/CXC/J.Drake et al.
LIGO-G050642-00-Z
Overview
• Sources • S2, S3, S4 results from the four search groups » All searches: no detections yet • S5 online
LIGO-G050642-00-Z Landry - PAC19
2
Astrophysical sources of gravitational waves
• • • • Compact binary systems » Neutron stars and black holes » Inspiral and merger » Probe internal structure, populations, and spacetime geometry Supernovae, GRBs » all-sky untriggered searches » burst signals in coincidence with electromagnetic and/or neutrino observations Stochastic background » Cosmological relic » Superposition of astrophysical sources Spinning neutron or quark stars » Known compact spinning stars, LMXBs » all-sky search for unknown objects (computing challenge)
LIGO-G050642-00-Z Landry - PAC19
3
Signal duration and template
Long duration Short duration no matched filter Burst search Stochastic search matched filter Inspiral search
LIGO-G050642-00-Z Landry - PAC19
CW search 4
Search groups
• LSC partitioned into four search groups • 2 Co-chairs (one theory, one experimental) • Mix of LIGO Lab and LSC representation, theorists, phenomenologists and experimentalists in each group
LIGO-G050642-00-Z Landry - PAC19
5
Burst group efforts
• Expected waveforms too numerous and complicated to calculate for matched filter analysis • Potential sources » supernovae, astrophysical phenomenae that power GRBs » mergers of compact objects » cosmic string cusps and kinks » disruptions of neutron stars • Search for untriggered bursts » Triggers, vetoes, upper limits » Injections of simulated waveforms » Multiple event trigger generator (ETG) investigations • Search for triggered bursts • Other work » Cosmic string search » Inspiral-burst-ringdown search » LIGO-TAMA joint analysis of S2 » LIGO-Virgo working group struck
LIGO-G050642-00-Z Landry - PAC19
6
S2 untriggered burst search
• bursts less than 1s, in band 100-1100Hz • 9.98d of data analyzed – improved sensitivity of machine and in analysis pipeline • Event triggers generated on triple-coincidence data, followed up by “r-statistic” waveform consistency test • Background set by similar analysis with time-shifted data • Set limit on rate of detectable gravitational wave bursts • Test efficiency of pipeline to detect particular waveforms: both ad hoc (gaussian, sine-gaussian) and astrophysically-motivated waveforms (core-collapse and binary black hole) applied • Set rate vs strength exclusion regions for these waveforms
LIGO-G050642-00-Z Landry - PAC19
7
S2 untriggered burst search
LIGO-G050642-00-Z Landry - PAC19
8
S2 triggered burst search
GRB 030329, confirmed supernova at z~0.17, or ~ 800Mpc away H1, H2 were in operation during S2.
A targeted search resulted in no detection HETE
LIGO-G050642-00-Z Landry - PAC19
9
Stochastic group efforts
• Cosmological relic, or, summation of noise sources from astrophysical epoch • Cross correlate detectors: uncorrelated noise integrates away while the signal to noise integrates up as the square root of time • Make use of optimal filter, which includes overlap reduction function • • Searches include » LHO-LLO » H1-H2 » LLO-Allegro W GW is the gravitational wave energy density per logarithmic frequency interval, divided by r c , the energy density required to close the universe
LIGO-G050642-00-Z Landry - PAC19
10
S3 stochastic background results
LIGO-G050642-00-Z
S3
Landry - PAC19
11
Inspiral group efforts
• predicted BNS inspiral rates » theoretical upper bound of 1/3 per year for LIGO S5 (Kalogera et. al, Ap J Lett
601
, L179 (2004)) » n.b. higher rates predicted for initial LIGO, based on identification of short GRBs as binary inspirals (astro-ph/0511254) • predicted BBH inspiral rates » theoretical upper bound of 1 per year for LIGO S5 • Matched template analysis • BNS • BBH • Primordial black holes • High mass ratios, spin • LIGO-Virgo • LIGO-TAMA
LIGO-G050642-00-Z Landry - PAC19
12
S2 binary neutron star search
No detection. Simulations from up to 1.5 Mpc away were “detected” in S2.
LIGO-G050642-00-Z
Effective distance of sources considered, and cumulative number of galaxies searched for in S2.
Landry - PAC19
13
S2 binary neutron star search
•
Triggers generated when event passes SNR cut
•
Chisquare test applied
•
Intersite coincidence Rate < 47 per year per Milky Way-like galaxy
False alarm coincident triggers, and simulated injections
LIGO-G050642-00-Z Landry - PAC19
14
Continuous waves search group efforts
• Known pulsar » Coherent time-domain method – Target known isolated and binary neutron stars – Pulsar timing provided by Jodrell Bank Pulsar Group » Markhov-Chain Monte Carlo method • Incoherent methods » Multiple methods (Powerflux, Stackslide, Hough) to test robustness and make crosschecks » All-sky searches and quick passing of data » Incoherent step in heirarchical search • Coherent frequency-domain (“F-statistic”) searches » Search for LMXBs » Isolated all-sky, wide-parameter searches – Best for blind search – Coherent step in heirarchical search » Einstein@home: distributed computing effort
LIGO-G050642-00-Z Landry - PAC19
15
S3, S4 time-domain preliminary results for known neutron stars
• • Closest to spin-down upper limit » Crab pulsar ~ 2.5 times greater than spin-down (f gw = 59.6 Hz, dist = 2.0 kpc) » h 0 = 3.5x10
-24 , e = 1.9x10
-3 » Assumes I = 10 38 kgm 2 Best limit on e: one pulsar below 1x10 -6
LIGO-G050642-00-Z
Crab pulsar NASA/CXC/SAO
Landry - PAC19
Pulsar timing : Jodrell Bank Pulsar Group 16
LIGO-G050642-00-Z
S2 Hough transform search
•
Semi-coherent method
•
Wide-parameter space
•
200-400Hz, one spindown parameter
•
Hough transform is applied to find pattern produced by Doppler shift and spindown of gravitational wave signal to the time-frequency plane of the data
•
95% confidence upper limits on h0, over whole sky and different spindown values in 1Hz bands are shown
•
Outliers: known instrument artifacts, or, not in triple coincidence
Landry - PAC19
17
• • • • • • • GEO-600 Hannover LIGO Hanford LIGO Livingston Current search point Current search coordinates Known pulsars Known supernovae remenants • • • • • User name User’s total credits Machine’s total credits Team name } Current work % complete
LIGO-G050642-00-Z
Einstein@home
Landry - PAC19
18
WITH INJECTIONS
Final S3 analysis results
WITHOUT INJECTIONS
• • • • Data: 60 10-hour stretches of the best H1 data Post-processing step on centralized server: find points in sky and frequency that exceed threshold in many of the sixty ten-hour segments analyzed 50-1500 Hz band shows no evidence of strong pulsar signals in sensitive part of the sky, apart from the hardware and software injections. There is nothing “in our backyard”.
Outliers are consistent with instrumental lines. All significant artifacts away from r.n=0 are ruled out by follow-up studies.
LIGO-G050642-00-Z Landry - PAC19
19
Instrument artifacts
• Some instrument lines permanent features, others can be mitigated, e.g. violin resonances and 1Hz lines, respectively • S4 Einstein@home search notches both classes of lines
LIGO-G050642-00-Z Landry - PAC19
20
S2, S3 analysis papers
• • • • • • • • • • •
Upper Limits on Gravitational Wave Bursts in LIGO’s Second Science Run
, Phys Rev D
72
, 062001 (2005)
A Search for Gravitational Waves Associated with the Gamma Ray Burst GRB030329 Using the LIGO Detectors
, Phys Rev D
72
, 042002 (2005)
Upper Limits from the LIGO and TAMA detectors on the rate of gravitational-wave bursts
, gr-qc/0507081, accepted for publication in Phys Rev D
Upper limits on a stochastic background of gravitational waves
, Phys Rev Lett
95
, 221101 (2005)
Search for gravitational waves from galactic and extra –galactic binary neutron stars
, Phys Rev D
72
, 082001 (2005)
Search for Gravitational Waves from primordial black hole binary coalescences in the galactic halo
, Phys Rev D
72
, 082002 (2005)
Search for gravitational waves from binary black hole inspirals in LIGO data
, gr qc/0509129, submitted to PRD
Limits on Gravitational-Wave Emission from Selected Pulsars Using LIGO Data
, B. Abbot et al., LIGO Scientific Collaboration; M. Kramer and A. G. Lyne, Phys Rev Lett
94,
181103 (12 May 2005)
First all-sky upper limits from LIGO on the strength of periodic gravitational waves using the Hough transform
, Phys Rev D 72, 102004 (2005)
To be submitted to gr-qc on the near horizon
: S2 joint LIGO-TAMA search for binary neutron stars, and, S2 coherent wide-parameter search for gravitational waves: all-sky and Sco X-1 Plus! Many technical papers on techniques, status etc.
LIGO-G050642-00-Z Landry - PAC19
21
S5
• S5 analyses online or near-online » Precision calibration in place: S5 V1 quality as good or better than the S4 V4 (final) calibration » h(t) to be produced online » Stochastic and CW searches fast-tracked (weeks-months), burst and inspiral searches in true real time • Stochastic search » Accumulated sensitivity calculated weekly » Fast-track H1-L1 search • CW search » Fast-track time-domain search for known objects, update monthly » Incoherent searches to scan weekly for new line artifacts, and make blind, all-sky searches on months of data » Goal: deep, wide-band, blind search, heirarchical employing Einstein@home
LIGO-G050642-00-Z Landry - PAC19
22
S5
• Burst search » Fast track triggered searches, and high-threshold searches for gold-plated events. Deeper searches offline. Realtime injections.
• Inspiral search » Fast track BNS and BBH searches. Realtime triggers in control room (10m). Coincidence, chi-square later (2h). Realtime injections
LIGO-G050642-00-Z Landry - PAC19
23