High-precision PTA data sets: a window to nano-Hertz GW Astronomy

Maturing Pulsar Timing Arrays (PTAs) are expected to expedite the detection of nano-Hertz gravitational waves (GWs) under the auspices of the International PTA (IPTA) consortium. This consortium plans to combine data from around 100 milli-second pulsars (MSPs) and resources from different PTA experiments for its Data Release 3 (IPTA DR3) to begin the low-frequency GW Astronomy era. The talk will include a description of the Indian PTA (InPTA) experiment where its uniqueness and contribution to the IPTA efforts will be highlighted. The InPTA has made its first official data release (DR1) of 14 MSPs, observed simultaneously in 300-500 MHz (Band 3) and 1260-1460 MHz (Band 5) frequency bands of the premier Indian radio astronomy facility, the upgraded Giant Metrewave Radio Telescope (uGMRT), for the international effort of ultra-low GW search. The next crucial milestone for the InPTA collaboration is its second data release (DR2) of five-year long GMRT data set for 29 MSPs. I will present some of these results, specifically the estimation of pulsar Time of Arrival (ToA) and Dispersion measures (DM). The emerging evidence of nano-hertz GWs is indicated in a recent announcement by worldwide PTA experiments, including InPTA, which will be briefly discussed. The implications of these results for nano-Hertz GWs emission due to galaxy mergers will be discussed. I will also briefly discuss my ongoing efforts to search for individual nHzGW events in such data sets.