We present the spin frequency and profile evolution of the radio pulsar J1119 - 6127 following magnetar-like X-ray bursts from the system in 2016 July .
Using data from the Parkes radio telescope , we observe a smooth and fast spin-down process subsequent to the X-ray bursts resulting in a net change in the pulsar rotational frequency of \Delta \nu \approx - 4 \times 10 ^ { -4 } Hz .
During the transition , a net spin-down rate increase of \Delta \dot { \nu } \approx - 1 \times 10 ^ { -10 } Hz s ^ { -1 } is observed , followed by a return of \dot { \nu } to its original value .
In addition , the radio pulsations disappeared after the X-ray bursts and reappeared about two weeks later with the flux density at 1.4 GHz increased by a factor of five .
The flux density then decreased and undershot the normal flux density followed by a slow recovery back to normal .
The pulsar ’ s integrated profile underwent dramatic and short-term changes in total intensity , polarization and position angle .
Despite the complex evolution , we observe correlations between the spin-down rate , pulse profile shape and radio flux density .
Strong single pulses have been detected after the X-ray bursts with their energy distributions evolving with time .
The peculiar but smooth spin frequency evolution of PSR J1119 - 6127 accompanied by systematic pulse profile and flux density changes are most likely to be a result of either reconfiguration of the surface magnetic fields or particle winds triggered by the X-ray bursts .
The recovery of spin-down rate and pulse profile to normal provides us the best case to study the connection between high magnetic-field pulsars and magnetars .