Simultaneous 50cm/10cm Single-pulse Polarization Observations of PSR J0953+0755

We report on simultaneous single-pulse observations of PSR J0953+0755 at 732 and 3100 MHz made using the Parkes 64-m radio telescope at two epochs.Another non-simultaneous 1369 MHz observation has also been analyzed to compare polarization properties of this pulsar at different frequencies.The previously reported lowlevel bridge emission between the interpulse and the main pulse is notably present at 732 MHz.However,the bridge emission becomes very weak or undetectable at higher frequencies.The cross-correlation analysis of simultaneous observations indicates that the total intensity of single pulses is highly correlated,which implies the same emission mechanism is responsible for the two frequencies.We confirm that the abrupt position angle jumps are non-orthogonal in this pulsar which probably result from the overlapping emission from two non-orthogonal polarization modes and the separation between different polarization modes is frequency-dependent.At all three frequencies,the dominant modes are clearly associated with negative values of circular polarization,but the association seems unclear for weak modes.