| Author(s) and Co-Author(s) with Affiliation: Jibin Jose(Department of Astronomy, Astrophysics, and Space Engineering, Indian Institute of Technology Indore, Indore 453552, India), Manoneeta Chakraborty(Department of Astronomy, Astrophysics, and Space Engineering, Indian Institute of Technology Indore, Indore 453552, India), Bhal Chandra Joshi(National Centre for Radio Astrophysics, SP Pune University Campus, Pune, Maharashtra, 411007, India), Manjari Bagchi(The Institute of Mathematical Sciences, C. I. T. Campus, Taramani, Chennai 600113, India), Shantanu Desai(Department of Physics IIT Hyderabad. Kandi, Telangana 502284), Nobleson K(Faculty of Advanced Science and Technology, Kumamoto University, 2-39-1 Kurokami, Kumamoto 860-8555, Japan) |
| Abstract: The second data release of Indian Pulsar Timing Array (InPTA), comprising seven years of high-precision monitoring of 27 millisecond pulsars leveraging the unique low-frequency, high-sensitivity capabilities of the upgraded Giant Metrewave Radio Telescope (uGMRT), has the potential for enabling a more robust stochastic gravitational wave background (SGWB) detection, which necessitates the characterization of the associated systematics. Pulsar Timing Array (PTA) sensitivity is limited by several noise processes, among which jitter noise—especially important for bright pulsars—arises from pulse-to-pulse variations in the amplitude and phase of the pulsar emission. These intrinsic fluctuations introduce stochastic contributions to the timing residuals that are not captured by time-of-arrival (TOA) uncertainties, ultimately limiting PTA sensitivity. In this work, we focus on the bright millisecond pulsar J1744−1134 from the InPTA sample and estimate the jitter noise using data from uGMRT in the 300–500 MHz band. Using both conventional and Bayesian analysis techniques, we obtain consistent estimates of the jitter amplitude and examine its scaling with the integration time and the bandwidth used for TOA estimation. Furthermore, utilizing low-frequency, wide-bandwidth coverage of uGMRT, we explore the frequency dependence of jitter noise within the 300–500 MHz band and assess the impact of jitter on high-precision dispersion measure (DM) estimates from low-frequency InPTA observations. This quantitative characterization of jitter will aid in optimizing the InPTA observing strategy for nanohertz gravitational waves and improve constraints on jitter contributions to TOA estimates, which is crucial for high-sensitivity timing observations with future facilities such as the Square Kilometre Array. |
