Broadband high-precision timing analysis of pulsars

Pulsars, which are rotating neutron stars, are excellent candidates for probing the physics of dense matter, strong gravity, and extreme magnetic fields because of their characteristic pulsation properties. Since these objects, especially the millisecond pulsars, have high rotational stability, their rotation can be accurately tracked by precisely measuring the times of arrival (TOAs) of their pulses and constructing a model to predict the TOAs of future pulses via a technique called pulsar timing. However, the TOA and the pulse shape are affected by the physical process occurring in the source and modulations experienced during the propagation of the pulses. Correction done on timing model to incorporate these will give insight to the physics of pulsars and interstellar medium. Since pulsar radiation follows power-law spectrum, timing observations are often conducted at radio wavelengths. These wavelengths are more susceptible to frequency-dependent effects such as scattering and dispersion, which can degrade the timing accuracy. Interestingly, for pulsars that have strong gamma-ray emission, timing can also be done using gamma-rays. However, a lower SNR of Gamma-ray pulsed emission makes this timing analysis challenging. Using data from the Fermi LAT (Large Area Telescope) telescope, we were working towards developing a pipeline to conduct gamma-ray timing of millisecond pulsars. We employ on Kernel Density Estimation (KDE) along with Gaussian fitting and Fourier series to construct the averaged template Gamma-ray pulse profile of the pulsar. Subsequently, we estimate the TOA of pulses over shorter epochs over time by using the Maximum Likelihood Estimator (MLE) approach to compute the timing offsets considering the constructed template profile. Later, we compare the timing parameters and residuals for the same pulsar with the radio counterparts from uGMRT, and give constraints to its noise characteristics, and pursue further the additional systematics observed. This study will enhance the understanding of the timing noise models of radio pulsar timing, incorporate greater accuracy on the timing residuals, and consequently, put robust constraints on the signature of gravitational wave background in the pulsar timing data.