Abstract Details
| Name: Abhimanyu Susobhanan Affiliation: TIFR, Mumbai Conference ID: ASI2019_199 Title : The Indian Pulsar Timing Array Experiment Authors and Co-Authors : Abhimanyu Susobhanan, Prakash Arumugasamy, Manjari Bagchi, Avishek Basu, Suryarao Bethapudi, Arpita Choudhary, Kishalay De, Shantanu Desai, Lankeswar Dey, Neelam Dhanda, Achamveedu Gopakumar, Yashwant Gupta, Bhal Chandra Joshi, M.A. Krishnakumar, Yogesh Maan, P.K. Manoharan, Arun Kumar Naidu, Dhruv Pathak, Ashis Paul, Siraprapa Sanpa-arsa, Mayuresh Surnis, Sai Chaitanya Susarla Abstract Type : Oral Abstract Category : General Relativity and Cosmology Abstract : The Indian Pulsar Timing Array (InPTA) is an experiment aimed at contributing to the International Pulsar Timing Array (IPTA) efforts to detect gravitational waves (GWs) in the sub-microHertz frequency range by observing an ensemble of millisecond pulsars (MSPs). Matured IPTA will be sensitive to both stochastic GW background as well as GWs from individual sources such as supermassive black hole binaries (SMBHBs). Our InPTA uses the upgraded Giant Metrewave Radio Telescope (uGMRT) and the Ooty Radio Telescope (ORT) to observe a carefully chosen sample of 20 MSPs at a bi-weekly cadence. InPTA has been now operational for the last three years providing a baseline for advanced statistical Gravitational Wave analysis similar to other international experiments and the first limits on stochastic GW are expected in the next six months. The wide frequency coverage provided by the uGMRT and the ORT should enable very accurate characterization of dispersion measure (DM) variations seen in some of the IPTA MSPs. At present, we are able to achieve time-of-arrivals (TOAs) with microsecond uncertainties and efforts are on to achieve TOAs with 100 ns uncertainties. This presentation will showcase the timing residuals and timing solutions obtained from our data, apart from preliminary results on individual pulsars. Additionally, we are pursuing several IPTA-relevant efforts such as developing prescriptions to search for nano-Hz GWs from SMBHBs in eccentric orbits and to characterize effects on the puslar signal due to diffractive interstellar scintillation. We also contribute to the IPTA by providing theoretical inputs, which include post-Newtonian-accurate timing residuals arising due to SMBHBs, an efficient method to solve the reactive orbital evolution equations to the leading order, as well as an improved binary model for compact nearly-circular pulsar binaries. |