Detection and Evolution of Linear Polarization of the Galactic Center Transient MAXI J1744-294

MAXI J1744−294 (MAXI J1477), likely a low-mass X-ray binary system, is a Galactic center transient source, detected at radio and X-ray wavelengths, located approximately 19″ southeast of Sgr A*. We report the first detection of its variable linear polarization in four epochs spanning 2025 April 4–9. The normalized 33 and 43 GHz Stokes parameters q and u over the four epochs imply a common Faraday rotation screen with a rotation measure (RM) = - 63606⁺⁸⁴⁴_-861 radians m⁻², the third largest RM detected within the Galaxy. The RM is consistent with that of the Galactic center magnetar PSR J1745−2900, giving the first direct evidence that MAXI J1744 lies within the Galactic center region, is bound to Sgr A*, and therefore is part of the nuclear star cluster. The uniformity in the Galactic center Faraday screen suggests that Sgr A*’s ≈−10⁵ radians m⁻² RM is intrinsic rather than originating from an unrelated line-of-sight source. On 2025 April 6, we detected a secondary polarized component with an additional RM ≈ −6000 radians m⁻², which was not seen at any other epoch. Assuming this secondary component primarily cools by synchrotron radiation, the implied local magnetic field strength is ∼15–30 G. In the context of a jetted X-ray binary progenitor, the additional RM screen and magnetic field strength are explainable with a short-lived knot in a putative jet.