| Abstract: | Pulsars are highly magnetized, rotating neutron stars emitting beams of electromagnetic radiation that when swept by line-of-sight these beams, look like a pulse of radiation, hence the name 'pulsar'. Millisecond pulsars (MSPs), with periods under 30 milliseconds, are exceptionally stable, making them ideal for gravitational wave detection and as components in pulsar timing arrays (PTAs). Pulsar timing involves measuring the time of arrivals (ToAs) and timing residuals over an extended period, to disentangle the phenomena that affect them like rotation, motion, and the influence of gravitational forces, with applications in detecting gravitational waves. The Giant Metrewave Radio Telescope (GMRT), covering a wide radio frequency range of 120 to 1460 MHz, has demonstrated excellent capability in precise low-frequency timing measurements.
This study extends the timing baseline of MSP J0248+4230 and MSP J1207-5050, discovered by the Giant Metrewave Radio Telescope (GMRT), from 5 to 11 years, using uGMRT observations. Achieving an rms deviation of 13.658 microseconds and 12.793 microseconds, we measured the spin period at 2.60083478563372 milliseconds with extraordinary precision. This implies the period will shift only 5 nanoseconds over 10,000 years, making it a highly stable timekeeper. For the first time, we also detected proper motion (µ_T = 1.35 ± 0.35 mas/year and µ_T = 7.13 ± 0.47 mas/year) for J0248+4230 and J1207-5050, indicating transverse velocities of 15.3 ± 4.4 km/s and 43.9 ± 5.3 km/s respectively. With an improved residual rms of 6.328 microseconds (50% improvement) and 6.336 microseconds (58% improvement), this study aligns with standards seen in MSPs listed in the European PTA. Extending this analysis could help qualify J0248+4230 and J1207-5050 for PTA projects, illustrating GMRT’s potential for advancing fundamental physics research.
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