Anomalous Acceleration of PSR J2043+1711 Raises Questions About Stellar Interactions

Recent research has revealed that PSR J2043+1711, a pulsar located in our galaxy, exhibits an anomalous acceleration of 3.5 ± 0.8 mm/s/yr. This finding deviates significantly from predictions made by equilibrium models of the Milky Way, indicating a discrepancy at a 4σ level. The study, conducted by Thomas Donlon II and 55 co-authors, suggests that this peculiar acceleration cannot be attributed to the expected gravitational interactions with orbiting dwarf galaxies, which typically account for around 1 mm/s/yr.

The authors propose two potential explanations for this unexpected behavior: a stellar flyby or the presence of a long-period orbital companion. They identified a main-sequence star in the Gaia Data Release 3 and Pan-STARRS Data Release 2 that has the appropriate mass and distance to account for the observed acceleration. However, the proper motions of the star and the pulsar differ significantly, suggesting that they are not gravitationally bound. The chance that this star is merely a line-of-sight coincidence is estimated at 1.6%.

Additionally, the researchers explored the possibility of a circumbinary companion in a hierarchical triple system with PSR J2043+1711. They found that the pulsar's spindown rate could be consistent with an outer object having an orbital period of 80,000 years, a companion mass of 0.3 solar masses, and a semi-major axis of 2000 AU.

The findings underscore the need for continued timing observations and future optical studies of PSR J2043+1711 to clarify the nature of this anomalous acceleration. The paper titled "The Anomalous Acceleration of PSR J2043+1711: Long-Period Orbital Companion or Stellar Flyby?" can be cited as arXiv:2407.06482.