An update on the Mock LISA Data Challenges

The LISA data analysis contest is now ready to roll: The Mock Lisa Data Challenge Taskforce has posted the challenge datasets, and everything is ready for challengers to get down to work looking for gravitational wave signals

LISA (the Laser Interferometry Space Antenna) is a joint ESA and NASA mission that will detect gravitational waves from massive black-hole mergers in the centers of galaxies, from the ultra-compact binary systems in our own Galaxy, and from many other sources, creating revolutionary research opportunities in astrophysics and fundamental physics. (See the public NASA and ESA LISA websites at http://lisa.nasa.gov and http://lisa.esa.int; see http://www.lisascience.org for a scientist's introduction to LISA science, and for updated LISA news.)

At the December 2005 meeting of the LISA International Science Team (LIST), a taskforce was established to organize several rounds of mock data challenges, with the purpose of fostering the development of LISA data analysis tools and capabilities, and of demonstrating the technical readiness already achieved by the gravitational-wave community in distilling a rich science payoff from the LISA data output.

The Mock LISA Data Challenge (MLDC) Taskforce has been working since then, to formulate challenge problems of maximum efficacy, to establish criteria for the evaluation of the analyses, to develop standard models of the LISA mission (orbit, noises) and of the LISA sources (waveforms, parameterization), to provide computing tools such as LISA response simulators, source waveform generators, and a Mock Data Challenge file format, and more generally to provide any technical support necessary to the challengers. The LISA Mock Data Challenges were proposed and discussed at meetings organized by the US and European LISA Project that were attended by a broad cross section of the international gravitational-wave community.

The challenges involve the distribution of several datasets, encoded in a simple standard format, and containing combinations of realistic simulated LISA noise with the signals from one or more LISA gravitational-wave sources of parameters unknown to the challenge participants, who are asked to return the maximum amount of correct information about the GW sources, and to produce technical notes detailing their work. The greatest scientific benefit of the challenges will come from the quantitative comparison of results, analysis methods, and implementations: thus, the challenges are meant to be blind tests, but not really contests.

The first challenge was approved at the June 2006 LIST meeting, and released shortly thereafter; the datasets can be downloaded at http://astrogravs.nasa.gov/docs/mldc. This first challenge focuses on the development and validation of building blocks and basic tools for LISA data analysis, and the datasets contain single sources or multiple non-overlapping sources in Gaussian and stationary instrumental noise, with no foregrounds. The results of the first challenge are due on December 1, 2006; they will be presented to the broad community and discussed in a dedicated session at the 11th Gravitational-Wave Data Analysis Workshop (December 18-21, 2006, at the Albert Einstein Institute, in Golm, Germany; see http://gwdaw11.aei.mpg.de). The second challenge, to be released before December's GWDAW11 and evaluated in June 2007, will focus on the analysis of datasets with many overlapping and interfering sources, in more realistic measurement conditions.

We encourage all interested parties to participate in the challenges. To learn more about them, go to the official MLDC website at http://astrogravs.nasa.gov/docs/mldc; a variety of software tools (including the LISA simulators used to generate the datasets, and code to read them from various computer languages) are available at http://sourceforge.net/projects/lisatools; the activities of the MLDC Taskforce can be tracked on their wiki, www.tapir.caltech.edu/dokuwiki/listwg1b:home .

Prospective challenge participants are asked to subscribe to the MLDC challenge mailing list (go to http://gravity.psu.edu/mailman/listinfo/lisatools-challenge), and to register with one of the MLDC co-chairs, Michele Vallisneri (vallis@caltech.edu) and Alberto Vecchio (av@star.sr.bham.ac.uk). Please direct any other query, contribution, or feedback to them. An extended MLDC taskforce teleconference, open to the questions and comments of all registered and prospective challengers, will be held on September 28. Details will be forthcoming on the MLDC challenge mailing list, and on the MLDC website.