A Millisecond Pulsar Binary Embedded in a Galactic Center Radio Filament

The Galactic Center is host to a population of extraordinary radio filaments, thin linear structures that trace out magnetic field lines running perpendicular to the Galactic plane. Using Murriyang, the 64 m Parkes radio telescope, we conducted a search for pulsars centered on the position of a compact source in the filament G359.0-0.2. We discovered a millisecond pulsar (MSP), PSR J1744-2946, with a period P = 8.4 ms, that is bound in a 4.8 hr circular orbit around a M_ c > 0.05 M_⊙ companion. The pulsar dispersion measure of 673.7 ± 0.1 pc cm^-3 and Faraday rotation measure of 3011 ± 3 rad m^-2 are the largest of any known MSP. Its radio pulses are moderately scattered due to multi-path propagation through the interstellar medium, with a scattering timescale of 0.87 ± 0.08 ms at 2.6 GHz. Using MeerKAT, we localized the pulsar to a point source embedded in a low-luminosity radio filament, the "Sunfish", that is unrelated to G359.0-0.2. Our discovery of the first MSP within 1^∘ of the Galactic Center hints at a large population of these objects detectable via high frequency surveys. The association with a filament points to pulsars as the energy source responsible for illuminating the Galactic Center radio filaments.