Low-frequency wideband timing of InPTA pulsars observed with the uGMRT

TL;DR

This study demonstrates that low-frequency wideband observations with the uGMRT can achieve high-precision pulsar timing and dispersion measure measurements, comparable to traditional high-frequency methods, enhancing prospects for gravitational wave detection.

Contribution

First application of wideband timing to low-frequency uGMRT data, achieving sub-microsecond ToA precision and microsecond-level DM measurements for PTA pulsars.

Findings

DM precisions of about 10^{-6} cm^{-3} pc achieved

ToA residuals in the sub-microsecond range

Results comparable to high-frequency PTA observations

Abstract

High-precision measurements of the pulsar dispersion measure (DM) are possible using telescopes with low-frequency wideband receivers. We present an initial study of the application of the wideband timing technique, which can simultaneously measure the pulsar times of arrival (ToAs) and DMs, for a set of five pulsars observed with the upgraded Giant Metrewave Radio Telescope (uGMRT) as part of the Indian Pulsar Timing Array (InPTA) campaign. We have used the observations with the 300-500 MHz band of the uGMRT for this purpose. We obtain high precision in DM measurements with precisions of the order 10^{-6}cm^{-3}pc. The ToAs obtained have sub-{\mu}s precision and the root-mean-square of the post-fit ToA residuals are in the sub-{\mu}s range. We find that the uncertainties in the DMs and ToAs obtained with this wideband technique, applied to low-frequency data, are consistent with the results obtained with traditional pulsar timing techniques and comparable to high-frequency results from other PTAs. This work opens up an interesting possibility of using low-frequency wideband observations for precision pulsar timing and gravitational wave detection with similar precision as high-frequency observations used conventionally.