Magnetars are a special subset of the isolated neutron star family, withX-ray and radio emission mainly powered by the decay of their immense magneticfields. Many attributes of magnetars remain poorly understood: spin-downglitches or the sudden reductions in the star's angular momentum, radio burstsreminiscent of extra-galactic Fast Radio Bursts (FRBs), and transient pulsedradio emission lasting months to years. Here we unveil the detection of a largespin-down glitch event (|Δν/ν|=5.8+2.6−1.6×10−6)from the magnetar SGR~1935+2154 on 2020 October 5 (+/- 1 day). We find nochange to the source persistent surface thermal or magnetospheric X-raybehavior, nor is there evidence of strong X-ray bursting activity. Yet, in thesubsequent days, the magnetar emitted three FRB-like radio bursts followed by amonth long episode of pulsed radio emission. Given the rarity of spin-downglitches and radio signals from magnetars, their approximate synchronicitysuggests an association, providing pivotal clues to their origin and triggeringmechanisms, with ramifications to the broader magnetar and FRB populations. Wepostulate that impulsive crustal plasma shedding close to the magnetic polegenerates a wind that combs out magnetic field lines, rapidly reducing thestar's angular momentum, while temporarily altering the magnetospheric fieldgeometry to permit the pair creation needed to precipitate radio emission.
|Publication status||Accepted/In press - 2023|