Big Dig

The LIGO and Virgo Collaborations quizzed ourselves: a group hid a realistic signal in our data. We wanted to confirm we could find a gravitational wave and identify its properties.

This was the first time the collaborations had tested the parameter estimation codes in realistic conditions. I was the parameter estimation review co-chair: my job was to make sure any claims we made about parameters we could measure were correct. I had a particularly active role, devising specific statements which were astrophysically interesting that our data could support (e.g., on spin; whether a NS was present); organizing efforts to track down possible sources of error; coordinating between people who understood the detector and its idiosyncracies (e.g., Andy Lundgren) and our review; et cetera.

This process established new directions for the parameter estimation group, culminating in a unified code library (lalinference); a unified signal model interface and library (lalsimulation); and other technical improvements and consistency checks.

The often-torturous process of code validation has continued for years (to 2013, as of this post), long after my active role in the review. With a well-understood codebase, signal model, and detector, gravitational wave scientists are now in a position to ask pointed questions about what information future gravitational wave measurements will provide.

For more information

• GW20100916 : gravitational wave scientists quiz themselve. This is what first gravitational wave detection might look like. Descriptions are available for the public and other scientists

• LIGO publications: Science summaries