Gravitational Wave Antenna

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Gravitational Wave Antenna Annex 1WG2 Joint
operation of antennas and network data analysis

• General objectives
• Promote the required coordination among the
  European operating detectors to search for
  gravitational wave signals.
• ensure coordination to perform joint
  observations among gw collaborations
• define the technical set-ups of pipelines of
  network data analysis
• define programs of joint observations with other
  telescopes
• (GRB, neutrino, optical)
• support the dissemination of the results of the
  gravitational wave searches
• compare results obtained by different
  observations

• Outcomes
• Recommendations for the planning of joint
  observations
• Recommendations for the technical aspects
  involved in the data exchange and analysis
• comparative studies on the results of
  observations
• comparative studies on the relevance of the
  detectors

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Gravitational Wave Antenna Annex 1WG2 Joint
operation of antennas and network data analysis

• Deliverables
• 1st year
• Annual report on the activity
• 2nd year
• Annual report on the activity
• Recommendation report on
• - planning of joint observations for different
  signal classes (burst, inspiral, quasi-periodic,
  stochastic)
• - technical proposals for the related data
  exchange and analysis

• My view on the role of WG2 within our community
• minimal exchange of information
• good foster development of common methodologies
  for joint observations
• optimal active role in the actual planning/
  implementation of joint observations
• being a network activity, WG2 has very different
  kind of targets from STREGA
• WG2 alone cannot be THE European group performing
  the actual data analysis
• recommendations instead of scientific papers
• promote common methodologies instead of producing
  scientific results

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WG2 plan of the first 18 months
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WG2 membership

• we extended the membership to additional
  researchers who expressed their interest in
  contributing actively and regularly to the WG2
• currently 19 members representing the major
  groups/collaborations. New memberships are
  possible, as long as the total number does not
  change much.
• time to time contributions by additional
  scientists are welcome and will be asked

Co-Chairs Bangalore S. Sathyprakash, Giovanni
A. Prodi
Members Pia Astone, Lucio Baggio, Laura
Brocco, Sergio Frasca, Ik Siong Heng, Andrzej
Krolak, Frederique Marion, Benoit Mours, Alicia
Sintes Olives, Antonello Ortolan, Archana Pai,
Maria Alessandra Papa, Joseph D. Romano, Alberto
Vecchio, Andrea Vicerè, Arlette de Waard, Graham
Woan appointed by GWA - Executive Board
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WG2 general organization

• regular phone conferences (twice per month)
• - Kick-off telecon held on July 15th, 2004
• - 7 telecons up to now
• - EGO provided telecon facility from Sep 2004
• web-site dedicated to internal discussion and
  information exchange
• electronic Bulletin Board at http//jwg.tn.infn.it
  
• web public section to inform Network
  participants on current activities
• keep face to face meetings to a minimum. We plan
  to use a significant fraction of the available
  annual budget to support reciprocal visits of
  members.
• opportunity to have the first face to face
  proposed in Dec. (satellite to VESF meeting or
  GWDAW)

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WG2 current activities

• formed 4 sub-groups to study
• - search for transient signals (including bursts
  and inspirals)
• - search for quasi-periodic signals
• - search for stochastic background
• - data and software standards
• These activities are starting up. First step is
  to make the science case for current and future
  earth-based network of detectors as well as
  discuss methodological issues.
• work in progress on the requests by WG3 to
  report on
• 1) effectiveness of a network of upgraded
  resonant and ITF detectors
• 2) sources to be detected with a network of
  second/third generation detectors.
• discussion on the feasibility and technical
  goals of a first exercise data exchange (weeks
  of simulated or real h(t) data from European
  detectors in frame format)
• review of status of agreements for joint gw
  observations involving European detectors gtgt
  future comparative report and recommendations

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Network effectiveness

• information on performances of single detectors.
  
• spectral sensitivities antenna patterns
• duty cycle
• detection efficiency and sensitivity versus time
  (choose a reference signal)
• statistics of the estimated parameters of gw
  candidates (outliers )
• estimate of the background of a joint
  observation
• interesting signal sources

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Shh of current generation detectors
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Methodological issues
Blind vs exploratory search a) exploratory
search experiment and analysis set-up are tuned
using the actual data in order improve the
compliance of the result with priors Pro high
parameter estimation potential Cons controverse
statistical interpretation (difficult to set up a
test on the prior) b) blind search tuning is
performed without looking at the results Pros
no statistical biases, it can be used to claim a
discovery with correct false alarm frequentistic
probability Cons statements are usually weaker
and less outstanding, unless the signal is very
clear In the case of gravitational wave
detection, assuming the prior that the first
detection will be made just on the basis of
statistical rarity, the adoption of blind
searches seems mandatory. BABAR F.C.Porter,
"Statistical issues in particle physics - a view
from BABAR", Proc. PHYSTAT2003, eds. L.Lyons,
R.Mount and R.Reitmeyer (SLAC, CA, Sept.2003)
p.186 also in SLAC-R-703 eConf C030908 as
WEAT002 (http//www.slac.stanford.edu/econf/C0309
08/papers/WEAT002.pdf)
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Methodological issues

• Exploiting amplitude information
• detectors have different amplitude sensitivity,
  because they have different power spectral
  density, and because of different
  geometry/position/orientationa) template search
• different sensitivity is not an issue, the same
  parameters of the source are estimated, with the
  proper calibrationb) template-less search We
  need an empirical quantity which have to
• same expected value in all detectors
• known statistical distribution Any procedure
  to extract this quantity is loosing signal power.
  This will produce a bias (which can be estimated
  if necessary when unfolding results toword any
  realistic known source) , but the important point
  is that the bias from different detectors be the
  same. Therefore, the same spectral weights will
  be implemented (in strain units). Special case
  restriction to a common bandwidth