Draft:Indian Pulsar Timing Array

• Comment: Unsourced? qcne (talk) 11:47, 13 July 2025 (UTC)

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The Indian Pulsar Timing Array (InPTA) is an Indo-Japanese collaboration aimed at detecting low-frequency, nanoHertz Gravitational Waves using the pulsar timing technique. This experiment uses the Giant Metrewave Radio Telescope to carry out observations of highly regular pulses from millisecond pulsars. This project is a part of the International Pulsar Timing Array, a global collaboration of pulsar timing array experiments that includes the Parkes Pulsar Timing Array, the North American Nanohertz Observatory for Gravitational Waves and the European Pulsar Timing Array.

Pulsar observations for detection of gravitational waves

The pulsar timing array experiments observe an ensemble of highly rotationally stable millisecond pulsars, distributed more or less uniformly in the sky, with high signal-to-noise ratio pulse detections and minimal signal distortion due to the interstellar medium, for searches of gravitational waves. Passing gravitational waves stretch and squeeze space-time between pulsars and the Earth, causing a slight variation in the time of arrival of the pulses from pulsars at the Earth. By precisely monitoring these times of arrival from pulsars over many years, correlated timing deviation across the pulsar array can reveal the presence of gravitational waves. Only a small number of pulsars satisfy these requirements.

The InPTA experiment observed a total of 27 millisecond pulsars spanning approximately an observation period of 7.5 years between 2016 and 2024. The InPTA observations were carried out by splitting the upgraded GMRT antennas into multiple subarrays to observe the same source simultaneously at different frequency bands. Each band had a bandwidth of 100 MHz or 200 MHz, depending on the observing epochs.