We report the results of an observational campaign using the Effelsberg 100-m
telescope of the pulsars J1746β2849, J1746β2850, J1746β2856 and
J1745β2912 located in the Central Molecular Zone (CMZ) close to the Galactic
centre in order to study rotation measure (RM) variations. We report for the
first time the RM value of PSR J1746β2850 to be β12234Β±181 rad
mβ2. This pulsar shows significant variations of RM of 300β400 rad
mβ2 over the course of months to years that suggest a strongly magnetized
environment. The structure function analysis of the RM of PSR J1746β2850
revealed a steep power-law index of 1.87β0.3+0.4β comparable to the
value expected for isotropic turbulence. This pulsar also showed large
dispersion measure (DM) variation of βΌ50 pc cmβ3 in an event lasting
a few months where the RM increased by βΌ200 rad mβ2. The large
difference in RM between PSR J1746β2849 and PSR J1746β2850 despite the
small angular separation reveals the presence of a magnetic field of at least
70 ΞΌG in the CMZ and can explain the lack of polarization in the radio
images of the region. These results contribute to our understanding of the
magnetic field in the CMZ and show similarities between the RM behaviours of
these pulsars and some fast radio bursts (FRBs).Comment: Accepted for publication on Monthly Notices of the Royal Astronomical
Society, 13 pages, 7 figure