Abstract:The phenomenon of subpulse drifting offers unique insights into the emission geometry of pulsars, and is commonly interpreted in terms of a rotating carousel of "spark" events near the stellar surface. We develop a detailed geometric model for the emission columns above a carousel of sparks that is entirely calculated in the observer's inertial frame, and which is consistent with the well-understood rotational effects of aberration and retardation. We explore the observational consequences of the model, includ… Show more
“…As a demonstration of the usefulness of the clustering algorithm, we show how it would detect PSR J0026–1955, the second pulsar discovery in the SMART survey (McSweeney et al 2022). In reality, the clustering algorithm was not implemented until after PSR J0026–1955 was discovered, but it is interesting to note that the first detection (chronologically) of this pulsar was a grating lobe detection (at the time, the candidates were being served up randomly), which motivated the development of the clustering algorithm in the first place.…”
Section: Data Processing and Analysismentioning
confidence: 96%
“…Given this, the discovery of PSR J0026–1955 in the first 10 min of observations, a pulsar with long-duration nulls and a nulling fraction of 77%, was remarkably fortuitous (see Figure 6). Details of the discovery, including an analysis of sub-pulse drifting, are reported in McSweeney et al (2022). As mentioned therein, this pulsar turned out to have already been reported as a candidate in the GBNCC survey but was blindly (and independently) discovered in the SMART survey data.Figure 9. MWA localisation of PSR J0026–1955 by performing a dense grid around the initial pulsar position from the discovery observation.…”
Section: Confirmation and Initial Follow-up Of Candidatesmentioning
confidence: 99%
“…The planned second-pass survey will extend the processing to the full 80-min observations and carry out more optimal searches in the DM parameter space, while incorporating searches for both long-period pulsars and millisecond pulsars. As such, the long dwell times of SMART (4800 s) can be exploited to search for pulsars with very long periods, like those discovered by LOFAR and MeerKAT (Tan et al 2018b; Caleb et al 2022), and provide increased sensitivity to objects that emit intermittently, for example, pulsars with long null durations such as PSR J0026–1955 (McSweeney et al 2022). In addition, the adopted strategy to archive recorded voltages offers additional avenues for future processing; for example, searches for millisecond pulsars through the application of novel hybrid dedispersion approaches that involve the use of coherent dispersion measure trials (CDMT), which was demonstrated by the LOFAR through the discovery of PSR J0952–0607 (Bassa et al 2017).…”
We present an overview of the Southern-sky MWA Rapid Two-metre (SMART) pulsar survey that exploits the Murchison Widefield Array’s large field of view and voltage capture system to survey the sky south of 30° in declination for pulsars and fast transients in the 140–170 MHz band. The survey is enabled by the advent of the Phase II MWA’s compact configuration, which offers an enormous efficiency in beam-forming and processing costs, thereby making an all-sky survey of this magnitude tractable with the MWA. Even with the long dwell times employed for the survey (4800 s), data collection can be completed in <100 hours of telescope time, while still retaining the ability to reach a limiting sensitivity of ∼2–3 mJy (at 150 MHz, near zenith), which is effectively 3–5 times deeper than the previous-generation low-frequency southern-sky pulsar survey, completed in the 1990s. Each observation is processed to generate ∼5000–8000 tied-array beams that tessellate the full ∼610 deg2 field of view (at 155 MHz), which are then processed to search for pulsars. The voltage-capture recording of the survey also allows a multitude of post hoc processing options including the reprocessing of data for higher time resolution and even exploring image-based techniques for pulsar candidate identification. Due to the substantial computational cost in pulsar searches at low frequencies, the survey data processing is undertaken in multiple passes: in the first pass, a shallow survey is performed, where 10 minutes of each observation is processed, reaching about one-third of the full search sensitivity. Here we present the system overview including details of ongoing processing and initial results. Further details including first pulsar discoveries and a census of low-frequency detections are presented in a companion paper. Future plans include deeper searches to reach the full sensitivity and acceleration searches to target binary and millisecond pulsars. Our simulation analysis forecasts ∼300 new pulsars upon the completion of full processing. The SMART survey will also generate a complete digital record of the low-frequency sky, which will serve as a valuable reference for future pulsar searches planned with the low-frequency Square Kilometre Array.
“…As a demonstration of the usefulness of the clustering algorithm, we show how it would detect PSR J0026–1955, the second pulsar discovery in the SMART survey (McSweeney et al 2022). In reality, the clustering algorithm was not implemented until after PSR J0026–1955 was discovered, but it is interesting to note that the first detection (chronologically) of this pulsar was a grating lobe detection (at the time, the candidates were being served up randomly), which motivated the development of the clustering algorithm in the first place.…”
Section: Data Processing and Analysismentioning
confidence: 96%
“…Given this, the discovery of PSR J0026–1955 in the first 10 min of observations, a pulsar with long-duration nulls and a nulling fraction of 77%, was remarkably fortuitous (see Figure 6). Details of the discovery, including an analysis of sub-pulse drifting, are reported in McSweeney et al (2022). As mentioned therein, this pulsar turned out to have already been reported as a candidate in the GBNCC survey but was blindly (and independently) discovered in the SMART survey data.Figure 9. MWA localisation of PSR J0026–1955 by performing a dense grid around the initial pulsar position from the discovery observation.…”
Section: Confirmation and Initial Follow-up Of Candidatesmentioning
confidence: 99%
“…The planned second-pass survey will extend the processing to the full 80-min observations and carry out more optimal searches in the DM parameter space, while incorporating searches for both long-period pulsars and millisecond pulsars. As such, the long dwell times of SMART (4800 s) can be exploited to search for pulsars with very long periods, like those discovered by LOFAR and MeerKAT (Tan et al 2018b; Caleb et al 2022), and provide increased sensitivity to objects that emit intermittently, for example, pulsars with long null durations such as PSR J0026–1955 (McSweeney et al 2022). In addition, the adopted strategy to archive recorded voltages offers additional avenues for future processing; for example, searches for millisecond pulsars through the application of novel hybrid dedispersion approaches that involve the use of coherent dispersion measure trials (CDMT), which was demonstrated by the LOFAR through the discovery of PSR J0952–0607 (Bassa et al 2017).…”
We present an overview of the Southern-sky MWA Rapid Two-metre (SMART) pulsar survey that exploits the Murchison Widefield Array’s large field of view and voltage capture system to survey the sky south of 30° in declination for pulsars and fast transients in the 140–170 MHz band. The survey is enabled by the advent of the Phase II MWA’s compact configuration, which offers an enormous efficiency in beam-forming and processing costs, thereby making an all-sky survey of this magnitude tractable with the MWA. Even with the long dwell times employed for the survey (4800 s), data collection can be completed in <100 hours of telescope time, while still retaining the ability to reach a limiting sensitivity of ∼2–3 mJy (at 150 MHz, near zenith), which is effectively 3–5 times deeper than the previous-generation low-frequency southern-sky pulsar survey, completed in the 1990s. Each observation is processed to generate ∼5000–8000 tied-array beams that tessellate the full ∼610 deg2 field of view (at 155 MHz), which are then processed to search for pulsars. The voltage-capture recording of the survey also allows a multitude of post hoc processing options including the reprocessing of data for higher time resolution and even exploring image-based techniques for pulsar candidate identification. Due to the substantial computational cost in pulsar searches at low frequencies, the survey data processing is undertaken in multiple passes: in the first pass, a shallow survey is performed, where 10 minutes of each observation is processed, reaching about one-third of the full search sensitivity. Here we present the system overview including details of ongoing processing and initial results. Further details including first pulsar discoveries and a census of low-frequency detections are presented in a companion paper. Future plans include deeper searches to reach the full sensitivity and acceleration searches to target binary and millisecond pulsars. Our simulation analysis forecasts ∼300 new pulsars upon the completion of full processing. The SMART survey will also generate a complete digital record of the low-frequency sky, which will serve as a valuable reference for future pulsar searches planned with the low-frequency Square Kilometre Array.
We report on the pulse-to-pulse energy distribution and longitude-resolved modulation properties of PSR J1631+1252 discovered by the Five-hundred-meter Aperture Spherical radio Telescope. Our analysis made use of the data acquired at 1250 MHz from the follow-up timing observations that lasted over a year. PSR J1631+1252 has a rotational period of ∼0.310 s, and a dispersion measure of ∼32.73 pc cm−3. The energy distribution is well described by a lognormal distribution, the parameters of which do not vary with time. We show that large modulation occurs across the bridge emission of the pulse profile, with sporadic bright bursts at the leading emission region. The fluctuation spectral analysis reveals the existence of subpulse drifting in the leading component with vertical spacing between the drift bands of 3.28 ± 0.08 pulse periods between consecutive drift bands. Possible physical mechanisms for subpulse drifting are discussed.
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