2 results
Low-frequency pulse-jitter measurement with the uGMRT I: PSR J0437–4715
- Tomonosuke Kikunaga, Shinnosuke Hisano, Neelam Dhanda Batra, Shantanu Desai, Bhal Chandra Joshi, Manjari Bagchi, T. Prabu, Keitaro Takahashi, Swetha Arumugam, Adarsh Bathula, Subhajit Dandapat, Debabrata Deb, Churchil Dwivedi, Yashwant Gupta, Shebin Jose Jacob, Fazal Kareem, K. Nobleson, Pragna Mamidipaka, Avinash Kumar Paladi, B. Arul Pandian, Prerna Rana, Jaikhomba Singha, Aman Srivastava, Mayuresh Surnis, Pratik Tarafdar
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- Journal:
- Publications of the Astronomical Society of Australia / Volume 41 / 2024
- Published online by Cambridge University Press:
- 16 April 2024, e036
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High-precision pulsar timing observations are limited in their accuracy by the jitter noise that appears in the arrival time of pulses. Therefore, it is important to systematically characterise the amplitude of the jitter noise and its variation with frequency. In this paper, we provide jitter measurements from low-frequency wideband observations of PSR J0437$-$4715 using data obtained as part of the Indian Pulsar Timing Array experiment. We were able to detect jitter in both the 300–500 MHz and 1 260–1 460 MHz observations of the upgraded Giant Metrewave Radio Telescope (uGMRT). The former is the first jitter measurement for this pulsar below 700 MHz, and the latter is in good agreement with results from previous studies. In addition, at 300–500 MHz, we investigated the frequency dependence of the jitter by calculating the jitter for each sub-banded arrival time of pulses. We found that the jitter amplitude increases with frequency. This trend is opposite as compared to previous studies, indicating that there is a turnover at intermediate frequencies. It will be possible to investigate this in more detail with uGMRT observations at 550–750 MHz and future high-sensitive wideband observations from next generation telescopes, such as the Square Kilometre Array. We also explored the effect of jitter on the high precision dispersion measure (DM) measurements derived from short duration observations. We find that even though the DM precision will be better at lower frequencies due to the smaller amplitude of jitter noise, it will limit the DM precision for high signal-to-noise observations, which are of short durations. This limitation can be overcome by integrating for a long enough duration optimised for a given pulsar.
The Indian Pulsar Timing Array: First data release
- Pratik Tarafdar, K Nobleson, Prerna Rana, Jaikhomba Singha, M. A. Krishnakumar, Bhal Chandra Joshi, Avinash Kumar Paladi, Neel Kolhe, Neelam Dhanda Batra, Nikita Agarwal, Adarsh Bathula, Subhajit Dandapat, Shantanu Desai, Lankeswar Dey, Shinnosuke Hisano, Prathamesh Ingale, Ryo Kato, Divyansh Kharbanda, Tomonosuke Kikunaga, Piyush Marmat, B. Arul Pandian, T. Prabu, Aman Srivastava, Mayuresh Surnis, Sai Chaitanya Susarla, Abhimanyu Susobhanan, Keitaro Takahashi, P. Arumugam, Manjari Bagchi, Sarmistha Banik, Kishalay De, Raghav Girgaonkar, A. Gopakumar, Yashwant Gupta, Yogesh Maan, P. K. Manoharan, Arun Naidu, Dhruv Pathak
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- Journal:
- Publications of the Astronomical Society of Australia / Volume 39 / 2022
- Published online by Cambridge University Press:
- 24 October 2022, e053
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We present the pulse arrival times and high-precision dispersion measure estimates for 14 millisecond pulsars observed simultaneously in the 300 $-$ 500 MHz and 1260 $-$ 1460 MHz frequency bands using the upgraded Giant Metrewave Radio Telescope. The data spans over a baseline of 3.5 years (2018-2021), and is the first official data release made available by the Indian Pulsar Timing Array collaboration. This data release presents a unique opportunity for investigating the interstellar medium effects at low radio frequencies and their impact on the timing precision of pulsar timing array experiments. In addition to the dispersion measure time series and pulse arrival times obtained using both narrowband and wideband timing techniques, we also present the dispersion measure structure function analysis for selected pulsars. Our ongoing investigations regarding the frequency dependence of dispersion measures have been discussed. Based on the preliminary analysis for five millisecond pulsars, we do not find any conclusive evidence of chromaticity in dispersion measures. Data from regular simultaneous two-frequency observations are presented for the first time in this work. This distinctive feature leads us to the highest precision dispersion measure estimates obtained so far for a subset of our sample. Simultaneous multi-band upgraded Giant Metrewave Radio Telescope observations in 300 $-$ 500 MHz and 1260 $-$ 1460 MHz are crucial for high-precision dispersion measure estimation and for the prospect of expanding the overall frequency coverage upon the combination of data from the various Pulsar Timing Array consortia in the near future. Parts of the data presented in this work are expected to be incorporated into the upcoming third data release of the International Pulsar Timing Array.