The Astrophysical Journal Letters (Jan 2024)

A Millisecond Pulsar Binary Embedded in a Galactic Center Radio Filament

  • Marcus E. Lower,
  • Shi Dai,
  • Simon Johnston,
  • Ewan D. Barr

DOI
https://doi.org/10.3847/2041-8213/ad4866
Journal volume & issue
Vol. 967, no. 1
p. L16

Abstract

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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 an 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 multipath 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.

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