| Name: | Shyam Sunder |
| Affiliation: | National Centre for Radio Astrophysics |
| Conference ID : | ASI2023_457 |
| Title : | Localisation and timing of GMRT discovered MSPs to aid sensitivity of PTA |
| Authors : | Shyam Sunder, Jayanta Roy, Bhaswati Bhattacharyya, Sanjay Kudale, Shubham Singh, Arpit Behera |
| Mode of Presentation: | Oral |
| Abstract Category : | Stars, ISM and Galaxy |
| Abstract : | Millisecond pulsars (MSPs) are fast rotating neutron stars that exhibit extremely stable behaviour over time. Their exceptional stability can be used as probes to measure variations in the ISM, intrinsic changes to pulsar magnetosphere, as well as probe for nHz gravitational waves [GWs]. The Pulsar Timing Array (PTA) experiments aim to identify the nHz spectrum of GWs signals in the pulsar timing data. The number of well-timed MSPs used in the experiment has the greatest influence on the detection of stochastic GW background.
The GHRSS survey and Fermi-LAT survey have resulted in discovery of 12 MSPs till now. High precision timing studies of these MSPs are hindered by large positional uncertainties associated with the discovery. Using a offline gated correlator of GMRT, we localise pulsars in arc-second accuracy to follow-up them using a sensitive phased array beam as well as to accelerate convergence towards initial timing model.
The follow-up study of four GMRT discovered MSPs using wide-band timing technique reveals microsecond order of timing residual in 2-4 years of follow-up using a GMRT wide-band receiver. In order to benefit from the larger instantaneous observing bandwidth of the uGMRT, we apply wide-band timing technique by modelling of the pulse profile as a function of radio frequency while making the ToA measurements. An significant improvement in timing precision is noticed while transitioning from narrow-band timing with legacy GMRT to wide-band timing with uGMRT. Aided by wide-band timing and the use of nearly the full GMRT array, a DM precision of 10^-5 pc cm^-3 and ToA precision of < 100 ns for a PTA MSP is achieved, which is 2-3 times better than the earlier GMRT results. In this presentation, we will show recently localised two MSPs and discuss the prospects of including them in PTA experiments to aid detection of GWs. |
