LSC-Virgo Externally Triggered Searches


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Analysis Projects

Please note: This page is no longer being maintained. An up-to-date list of Externally Triggered Searches is maintained at Access is restricted to members of the LIGO Scientific Collaboration and the Virgo Collaboration. For more information please contact the ExtTrig Coordinators.

GWs associated with GRBs

Scientific goals:

Use external triggers of possible GRB events received through the GCN and IPN networks (up to a few events per day) in searching for GW counterparts of GRBs. For pre-S6-VSR2 GRBs (mid 2009) the preliminary search is done via automatized online search algorithm, and final results are taken from an offline analysis. For most S6-VSR2 GRBs the final search results will come from an improved online analysis. Exceptionally close-by or remarkably energetic events during Astrowatch periods shall also warrant specialized offline searches. The sample of triggers is also used to search for a collective GW signature associated with the GRB population.

Data set(s):

S2, S2-S3-S4, S5-VSR1, A5, S6-VSR2

Analysis approaches:

People involved (from ExtTrig/Bursts group):

Laura Cadonati (Amherst), Alessandra Corsi (Roma), Mark Edwards (Cardiff), Ray Frey (Oregon), Emelie Harstad (Oregon), Gareth Jones (Cardiff), Isabel Leonor (Oregon), Aaron Meyer (Amherst), Peter Raffai (Eotvos), Tiffany Summerscales (Andrews), Patrick Sutton (Cardiff).

Projected timeline:

The S5-VSR1 search is currently being finalized, with a paper release planned for mid-2009. A search for GWs associated with Astrowatch GRBs (late 2007 - mid 2009) is underway.

Links to analysis and review summary pages for past and current searches can be found at the Burst projects page. Details on the Compact Binary Coalescence (CBC) group matched-filter search for GWs associated with short GRBs can be found on the CBC page.

GWs associated with SGR flares

Scientific goals: To observe excess gravitational wave power in the LIGO detectors associated with SGR events and in case of the absence of a detection place a stringent upper limit on the gravitational wave emission. Addresses transient signals, ringdowns and quasiperiodic oscillation of the star.

Data set(s): Astrowatch, S4, S5

Analysis approaches:

Relationship to other projects:

People involved: Peter Kalmus (Columbia), Luca Matone (Columbia), Graham Woan (Glasgow), Szabolcs Marka (Columbia), Matthew Pitkin (Glasgow), Ik Siong Heng (Glasgow) James Clark (Glasgow)


Documentation links:

Presentations and paper drafts

  1. Luca Matone "Search for Gravitational Wave radiation associated with the pulsating tail of the SGR 1806-20 hyperflare of Dec. 27th, 2004 using the LIGO detectors" August LSC meeting 2006 [ G060405-00.pdf ]
  2. Peter Kalmus "Search for the short burst signature of the SGR 1806-20 giant flare" f2f August LSC 2006 [ PDF ]
  3. Peter Kalmus et al. "Search method for unmodeled transient gravitational waves associated with SGR flares", accepted for publication in CQG

Projected timeline:

GWs associated with high energy neutrinos

Scientific goal(s): Search for gravitational wave (GW) events that are coincident in direction and/or in time with events detected by high-energy neutrino (HEN) observatories. The observation of such coincidence would be a landmark event and can also provide observational evidence that GW and HEN originate from a common astrophysical source. Collaborating with the ANTARES and IceCube Collaborations can enable this forward-looking multidisciplinary research. Fundamental astrophysical goals motivate this quest. Foremost, applying coincidence tests may allow true astrophysical signals to stand above noise events, enabling detection of signals that would otherwise be lost. Beyond the increased search sensitivity, coincident detection of GW and HEN arriving from the same astronomical source would probe important scientific questions that are out of reach for a single channel detector. Some plausible high-energy events could be hidden from electromagnetic observations due to e.g., optically thick environment. Combined GW+HEN observations might still reveal the properties and the underlying physics of such elusive sources.

Data sets: S5, S6, advLIGO

Analysis approach: See CQG paper and APS presentations on the topic.

Relationship to other projects:

People involved: Y.Aso(Caltech,LSC), M.Barsuglia(APC,VIRGO), I.Bartos(Columbia,LSC), P.Brady(UWM,LSC), S.Capozziello(Napoli,VIRGO), E.Chassande-Mottin(APC,VIRGO), S.K.Chatterji(MIT,LSC), J.Clayton(UWM,LSC), F.Garufi(Napoli,VIRGO), B.Hughey(MIT,LSC), S.Kandhasamy(UMN,LSC), S.Klimenko(Florida,LSC), V.Mandic(UMN,LSC), Sz.Marka(Columbia,LSC), Zs.Marka(Columbia,LSC), L.Milano(Napoli,VIRGO), C.D.Ott(Caltech, LSC), I.DiPalma(AEI,LSC,GEO), M.A.Papa(AEI,LSC,GEO), J.Rollins(Columbia,LSC), A.Searle(Caltech,LSC), P.Sutton(Cardiff,LSC,GEO), D.Tanner(Florida,LSC), E.Thrane(UMN,LSC),


The following tentative dates are compatible with the data taking schedule of the collaborations: 1. The methods paper draft is expected around Fall 2009. 2. The S5/VSR1 observational paper draft is expected before the Spring of of 2010. 3. The S6/VSR2 observational paper draft is expected by the end of S6 or related data runs of the partner collaborations (whichever comes earlier). 4. It is expected that the MoUs will be in place by Fall 2009 to enable the timeline above.

Documentation links:

See CQG paper, Exttrig Webpage, APS presentations, NASA ADS Library links and Proposal

Presentations and paper drafts:

See CQG paper, APS presentations, and Proposal

Projected timeline:

See Milestones...

GWs associated with core-collapse supernova neutrinos from the Galactic neighboorhood

Scientific goal(s): Neutrino observatories (SuperK, LVD) are capable detecting low-energy neutrinos originating from core collapse supernoves in the Galactic neighboorhood, ~O(100kpc). Although the probability of a Galactic supernova event (warranting the deployment of a SNEWS trigger) is small, there are methods being developed to attempt to identify probable events from somewhat larger than galactic distances using neutrino and gravitational wave channels in coincidence/coherently.

Data sets: S5

Analysis approach: Correlate trigger times. Use (semi)coherent methods.

Relationship to other projects:

People involved: Isabel Leonor (Oregon), et. al.


Documentation links:

Presentations and paper drafts:

Projected timeline:

GWs associated with optical supernovae

Scientific goals: Search for gravitational waves associated optical supernovae (type Ic, II) with a priority of relatively closeby events with well detected light curve signatures (to minimize the uncertainity in the timing of the event). By studying the light curves of the supernovae and making estimates on the expected time delay between the core collapse and the photon emission, we can identify data segments to search for GW signals. As core collapse supernovae associated with GW signals tend to produce relatively intense signals, the aim is to look for supernovae of redshifts <= 0.008-0.009. Rollins and Kamat are presently spearheading SN2006BP.

Data sets: S5

Analysis approach: Develop specialized off-line search algorithm to search for gravitational signature of observed optical supernovae based on coherent analysis methods.

Relationship to other projects: GW-Neutrino coincident search: The search developed here must be usable to execute a prompt follow up search for an eventual exceptionally close-by supernova reported by the Supernova Early Warning System (SNEWS). The probability of such an event to be detected by the neutrino observatories with SNEWS defined false alarm rate (1 in 100) is very small (1 in ~30 years).

People involved: Jamie Rollins (Columbia), Sharmila Kamat (Columbia), Virginio Sannibale (Caltech), Ray Frey (Oregon)


Documentation links:

Presentations and paper drafts:

Projected timeline:

GWs associated with neutron star quasi-normal modes

Scientific goals: Neutron star quasi-normal modes may be excited by various mechanisms, including pulsar glitches and soft-gamma repeater (SGR) flares, both of which provide external triggers for a GW search. The neutron star fundamental mode (f-mode) should produce a distinct GW ringdown signal, with frequencies within the 1-4 kHz range and decay timescales of ~0.05-0.5s, allowing for a targeted template-based search within a time-window around the external trigger.

Data sets: S4, S5, Astrowatch

Analysis approach: We are developing an externally triggered, evidence based search whereby Bayesian model selection is used to compute the probability that interferometer data contains a neutron star GW ringdown, relative to the probability that the data contains only noise or some event from a catalogue of instrumental glitches. Our search is currently focused on 1) pulsar glitches, where the trigger is a 'glitch' in pulsar spin-down observations and 2) SGR flares, where the trigger comes from high-energy observations of flares from known SGRs.

Relationship to other projects: GWs from SGR flares: the first target for our evidence-based search is the Dec. 27th 2004 event, SGR1806-20. The evidence-based search method could be expanded into many other areas, where we have competing models for on and off-source data.

People involved: James Clark (Glasgow), Ik Siong Heng (Glasgow), Matt Pitkin (Glasgow), Graham Woan (Glasgow)


Documentation links:

Presentations and paper drafts:

Projected timeline:

  1. Produce methodology paper in time for GWDAW
  2. Investigate robustness in real IFO data
  3. Methods/proof of concept presentation at GWDAW
  4. Convert code into search pipeline

Search for GWs from compact binary inspirals associated with short hard GRBs

Scientific goal(s):

It is widely believed that the progenitors of most short hard gamma-ray bursts a merging neutron-star--black-hole or neutron-star--neutron-star binaries. This search test this possible relationship by searching for gravitational waves from the inspiral which precedes the merger. In the absence of gravitational-wave detection, the search will give an exclusion region in the mass-distance plane which can be used to constrain possible progenitor binaries.

Data sets:

S5-VSR1, S6-VSR2

Analysis approach:

Standard inspiral pipeline, modified to search for coincidences between GRBs and inspiral triggers in a short time window. Taking into account the known time-delay between the two LIGO sites, the background can be reduced to allow a deep search in times around the GRB event.

This project is being pursued in the CBC search group.

People involved (partial list):

Patrick Brady (UWM), Alexander Dietz (Anecy), Nick Fotopolous (UWM).

Projected timeline:

The S5-VSR1 search is currently being finalized, with a paper release planned for mid-2009.

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