A Multimessenger Search for the Binary in 3C 66B
I led a targeted search for nanohertz continuous gravitational waves from the proposed supermassive black-hole binary in the radio galaxy 3C 66B, combining Parkes Pulsar Timing Array data with electromagnetic constraints.
Why 3C 66B?
Very-long-baseline interferometry has suggested orbital motion in the core of 3C 66B, making it a particularly interesting target for a pulsar-timing-array search. A known sky location and electromagnetic information let us probe the candidate more directly than an all-sky search.
What we found
The data do not support a gravitational-wave detection, but they also do not completely rule out the proposed binary. We constrained the source-frame chirp mass to below 6.90 × 108 M☉ and the gravitational-wave strain to log10 h0 < −14.44 at 95% credibility. These limits exclude more than half of the parameter space allowed by the electromagnetic model.
The project also develops a joint electromagnetic–gravitational-wave likelihood. This provides a route to tighter binary constraints and, when a source is detected, targeted standard-siren measurements.