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Accepted manuscript

The Southern-sky MWA Rapid Two-metre (SMART) pulsar survey—III. A census of millisecond pulsars at 154 MHz

Published online by Cambridge University Press:  01 September 2025

C. P. Lee*
Affiliation:
International Centre for Radio Astronomy Research, Curtin University, Bentley, WA 6102, Australia
N. D. R. Bhat
Affiliation:
International Centre for Radio Astronomy Research, Curtin University, Bentley, WA 6102, Australia
B. W. Meyers
Affiliation:
International Centre for Radio Astronomy Research, Curtin University, Bentley, WA 6102, Australia Australian SKA Regional Centre (AusSRC), Curtin University, Bentley, WA 6102, Australia
S. J. McSweeney
Affiliation:
International Centre for Radio Astronomy Research, Curtin University, Bentley, WA 6102, Australia
W. van Straten
Affiliation:
Manly Astrophysics, 15/41-42 East Esplanade, Manly, NSW 2095, Australia
C. M. Tan
Affiliation:
International Centre for Radio Astronomy Research, Curtin University, Bentley, WA 6102, Australia
M. Xue
Affiliation:
National Astronomical Observatories, Chinese Academy of Sciences, 20A Datun Road, Chaoyang District, Beijing 100101, People’s Republic of China
N. A. Swainston
Affiliation:
International Centre for Radio Astronomy Research, Curtin University, Bentley, WA 6102, Australia CSIRO Space and Astronomy, PO Box 1130, Bentley, WA 6102, Australia
S. M. Ord
Affiliation:
CSIRO Astronomy and Space Science, PO Box 76, Epping, NSW 1710, Australia
G. Sleap
Affiliation:
International Centre for Radio Astronomy Research, Curtin University, Bentley, WA 6102, Australia
S. E. Tremblay
Affiliation:
National Radio Astronomy Observatory, 1011 Lopezville Road, Socorro, NM 87801, USA
A. Williams
Affiliation:
International Centre for Radio Astronomy Research, Curtin University, Bentley, WA 6102, Australia
*
Author for correspondence: C. P. Lee, Email: christopher.lee@icrar.org.
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Abstract

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Observations of millisecond pulsars (MSPs) at low radio frequencies play an important role in understanding the Galactic pulsar population and characterising both their emission properties and the effects of the ionised interstellar medium on the received signals. To date, only a relatively small fraction of the known MSP population has been detected at frequencies below 300 MHz, and nearly all previous MSP studies at these frequencies have been conducted with northern telescopes. We present a census of MSPs in the SMART pulsar survey, covering declinations south of +30° at a centre frequency of 154 MHz. We detected 40 MSPs, with 11 being the first published detections below 300 MHz. For each detection, we provide coherently-dedispersed full-polarimetric integrated pulse profiles and mean flux densities. We measured significant Faraday rotation measures (RMs) for 25 MSPs, and identified apparent phase-dependent RM variations for three MSPs. Comparison with published profiles at other frequencies supports previous studies suggesting that the pulse component separations of MSPs vary negligibly over a wide frequency range due to their compact magnetospheres. We observe that integrated pulse profiles tend to be more polarised at low frequencies, consistent with depolarisation due to superposed orthogonal polarisation modes. The results of this census will be a valuable resource for planning future MSP monitoring projects at low frequencies, and will also help to improve survey simulations to forecast the detectable MSP population with the SKA-Low.

Information

Type
Research Article
Creative Commons
Creative Common License - CCCreative Common License - BY
This is an Open Access article, distributed under the terms of the Creative Commons Attribution licence (https://creativecommons.org/licenses/by/4.0/), which permits unrestricted re-use, distribution and reproduction, provided the original article is properly cited.
Copyright
© The Author(s), 2025. Published by Cambridge University Press on behalf of Astronomical Society of Australia