The High Time Resolution Universe Pulsar Survey I: System configuration and initial discoveries (1006.5744v2)

Abstract: We have embarked on a survey for pulsars and fast transients using the 13-beam Multibeam receiver on the Parkes radio telescope. Installation of a digital backend allows us to record 400 MHz of bandwidth for each beam, split into 1024 channels and sampled every 64 us. Limits of the receiver package restrict us to a 340 MHz observing band centred at 1352 MHz. The factor of eight improvement in frequency resolution over previous multibeam surveys allows us to probe deeper into the Galactic plane for short duration signals such as the pulses from millisecond pulsars. We plan to survey the entire southern sky in 42641 pointings, split into low, mid and high Galactic latitude regions, with integration times of 4200, 540 and 270 s respectively. Simulations suggest that we will discover 400 pulsars, of which 75 will be millisecond pulsars. With ~30% of the mid-latitude survey complete, we have re-detected 223 previously known pulsars and discovered 27 pulsars, 5 of which are millisecond pulsars. The newly discovered millisecond pulsars tend to have larger dispersion measures than those discovered in previous surveys, as expected from the improved time and frequency resolution of our instrument.

• The paper introduces a novel survey design using a 400 MHz digital backend to efficiently detect pulsars and fast transients.
• It demonstrates high time and frequency resolution, anticipating the discovery of about 400 pulsars, including 75 millisecond pulsars.
• The enhanced survey capabilities provide new prospects for testing gravitational theories and studying the interstellar medium.

Overview of the High Time Resolution Universe Pulsar Survey I: System Configuration and Initial Discoveries

The paper "The High Time Resolution Universe Pulsar Survey I: System configuration and initial discoveries", authored by Keith et al., presents a comprehensive overview of a large-scale survey utilizing the Parkes radio telescope's 13-beam Multibeam receiver. This survey aims to discover new pulsars and characterize fast transients with an enhanced time resolution compared to previous surveys. The key advancements include the use of a digital backend that allows 400 MHz of bandwidth to be recorded for each beam, segmented into 1024 channels sampled every 64 μs, facilitating more efficient exploration of pulsars with short duration signals.

Survey Design and Implementation

The High Time Resolution Universe (HTRU) survey is partitioned into three components: low, mid, and high Galactic latitude regions, targeting the entire southern sky through 42,641 pointings. Different integration times of 4200, 540, and 270 seconds are employed corresponding to the three components, enhancing the survey's sensitivity to millisecond pulsars (MSPs) and fast transients. The increased frequency resolution enables probing deeper into the Galactic plane, particularly useful for detecting signals from MSPs that previous surveys like the Parkes Multibeam Pulsar Survey (PMPS) might have missed due to dispersive smearing.

Numerical Findings and Predictions

Quantitative simulations anticipate the discovery of approximately 400 pulsars, including 75 MSPs, signaling an advancement in the detection capacity compared to earlier surveys. Preliminary outcomes from the mid-latitude survey, which is around 30% complete, have already resulted in the identification of 27 new pulsars with five being MSPs. The improved time and frequency resolution results in detecting MSPs with larger dispersion measures than those revealed in prior endeavors, demonstrating the survey's efficacy.

Implications and Future Directions

The implications of this research are twofold. Practically, the survey expands the known pulsar catalog, providing new targets for subsequent timing studies, including tests of theories of gravity and the interstellar medium. In theory, it enhances our understanding of MSP population statistics and distribution within the Galaxy. The technological advancements in pulsar searching presented here suggest a potential paradigm shift in how future sky surveys might be conducted, specifically with the adoption of digital systems enhancing frequency and temporal fidelity.

New findings reinforce the need for digital backend systems, indicating that future astronomical instrumentation will likely continue down this path of increased digitization for even greater sensitivity and resolution. Furthermore, the discovery of more exotic pulsars, such as radio-loud magnetars, underscores the diversity of pulsar types and their evolving observational characteristics, hinting at the complex and varied astrophysical processes at play.

Conclusion

The paper contributes significantly to the field by detailing a well-structured approach to detect pulsars and transients using a novel configuration of the Parkes radio telescope. The HTRU survey's early discoveries emphasize the potential for further breakthroughs in observing exotic astrophysical phenomena and extend the frontier of pulsar astronomy. This research sets a precedence for future surveys, potentially influencing the design of future all-sky observations aiming for high time resolution data acquisition.