The Parkes Pulsar Timing Array Project

Abstract

A 'pulsar timing array' (PTA), in which observations of a large sample of pulsars spread across the celestial sphere are combined, allows investigation of 'global' phenomena such as a background of gravitational waves or instabilities in atomic timescales that produce correlated timing residuals in the pulsars of the array. The Parkes Pulsar Timing Array (PPTA) is an implementation of the PTA concept based on observations with the Parkes 64-m radio telescope. A sample of 20 ms pulsars is being observed at three radio-frequency bands, 50 cm (ß700 MHz), 20 cm (ß1400 MHz), and 10 cm (ß3100 MHz), with observations at intervals of two to three weeks. Regular observations commenced in early 2005. This paper describes the systems used for the PPTA observations and data processing, including calibration and timing analysis. The strategy behind the choice of pulsars, observing parameters, and analysis methods is discussed. Results are presented for PPTA data in the three bands taken between 2005 March and 2011 March. For 10 of the 20 pulsars, rms timing residuals are less than 1 μs for the best band after fitting for pulse frequency and its first time derivative. Significant 'red' timing noise is detected in about half of the sample. We discuss the implications of these results on future projects including the International Pulsar Timing Array and a PTA based on the Square Kilometre Array. We also present an 'extended PPTA' data set that combines PPTA data with earlier Parkes timing data for these pulsars.

Gravitational waves from binary supermassive black holes missing in pulsar observations

“…We analyzed observations obtained with the 64-m Parkes Telescope as part of the Parkes Pulsar Timing Array (PPTA) project (6). Our data set spans approximately 11 years, from MJD 53041 to 56992, which is approximately 3.5 years longer than a previously analyzed multiwavelength data set (8).…”

“…All of the observations reported here were made in the 10 cm band of the 10-cm/50-cm receiver, at a central frequency of 3100 MHz, with bandwidths of 512 or 1024 MHz and individual durations of usually 3840 s. The observations were recorded with a set of autocorrelation and digital-filterbank spectrometers. The data were analyzed using previously described procedures (6). Observations were referred to the solar-system barycentre using the DE421 solar-system ephemeris and the 2014 realization of terrestrial time published by BIPM (30).…”

The gravitational-wave discovery space of pulsar timing arrays

“…On timescales ∼ 5 years (f ∼ 10 −8.2 Hz), the residuals appear to be dominated by white components ( [6,32]; see also Figs. 10 and 11 of [8] for a visual representation of noise effects in PPTA pulsars). Even if σ 2 ≈ κ 2 at frequencies ∼10 −8.2 Hz, at higher frequencies (≳10 −7 Hz), the variance from white processes will exceed that of any red processes with relatively shallow spectra (x ≈ 1) by a factor of approximately 15; for red processes with steeper spectra (x ≈ 4), the ratio will be even larger.…”

“…The last few years have seen a strong renewed interest in these searches, with the formation of three major pulsar timing programs: the European Pulsar Timing Array (EPTA, [4,5]), the North American Nanohertz Observatory for Gravitational Waves (NANOGrav, [6,7]), and the Australian Parkes Pulsar Timing Array (PPTA, [8,9]), which have now joined into a global collaboration, the International Pulsar Timing Array (IPTA, [10,11]). …”

HIPSR: A Digital Signal Processor for the Parkes 21-cm Multibeam Receiver

“…7 shows the pulse profile produced from this observation. BPSR was recording with a sampling interval of 64 µs; therefore, the main peak of the pulsar, which has a full width at half maximum of around 140 µs (Manchester et al, 2013), is resolved with only a few time samples.…”