[Paper Review] The Parkes Pulsar Timing Array Third Data Release

Andrew Zic, Daniel J. Reardon+32 more|arXiv (Cornell University)|Jun 28, 2023

Radio Astronomy Observations and TechnologyPhysics and Astronomy13 citations

TL;DR

This paper presents the Parkes Pulsar Timing Array third data release (DR3), combining an updated DR2 with ~3 years of ultra-wide-bandwidth observations from the Murriyang telescope, yielding ToAs, timing models, and auxiliary data for 32 pulsars over up to 18 years.

ABSTRACT

We present the third data release from the Parkes Pulsar Timing Array (PPTA) project. The release contains observations of 32 pulsars obtained using the 64-m Parkes "Murriyang" radio telescope. The data span is up to 18 years with a typical cadence of 3 weeks. This data release is formed by combining an updated version of our second data release with $\sim 3$ years of more recent data primarily obtained using an ultra-wide-bandwidth receiver system that operates between 704 and 4032 MHz. We provide calibrated pulse profiles, flux-density dynamic spectra, pulse times of arrival, and initial pulsar timing models. We describe methods for processing such wide-bandwidth observations, and compare this data release with our previous release.

Motivation & Objective

• Provide a public data release comprising calibrated pulsar observations from the Parkes telescope (DR3).
• Combine an updated DR2 with ~3 years of new ultra-wide-bandwidth observations to improve timing and noise characterization.
• Deliver calibrated pulse profiles, flux-density spectra, ToAs, and initial pulsar timing models for use in gravitational-wave searches.

Proposed method

• Observe 32 pulsars with the 64-m Parkes Murriyang telescope using the ultra-wide-bandwidth receiver (704–4032 MHz).
• Split UWL data into eight sub-bands and form four frequency channels per sub-band to enable wide-band timing with frequency-dependent templates.
• Cross-correlate observations with wide-band templates to obtain ToAs using Fourier-domain Monte Carlo methods in psrchive.
• Reprocess PPTA DR2 pulse profiles with MeerGuard, update ephemerides, and generate frequency-dependent templates for four channels per observation.

Experimental results

Research questions

• RQ1 How does the DR3 data set improve pulsar timing precision and GW sensitivity relative to DR2?
• RQ2 What are the benefits of wide-band, frequency-dependent timing for mitigating dispersion measure and profile evolution systematics?
• RQ3 What new pulsars are included in DR3 and how do their ToAs and residuals compare across observing systems?
• RQ4 How do timing offsets between backends affect the timing models, and how are they corrected?
• RQ5 What auxiliary data products (dynamic spectra, flux calibrations) enhance multi-facet astrophysical analyses beyond GW searches?

Key findings

• DR3 combines DR2 reprocessed data with ~3 years of new UWL observations, totaling 32 pulsars with up to 18 years of data.
• New UWL observations provide continuous frequency coverage from 704 to 4032 MHz, enabling improved DM measurements and wide-band timing.
• The data release includes calibrated pulse profiles, flux-density dynamic spectra, pulse ToAs, and initial timing models for all pulsars.
• Median ToA uncertainties across UWL sub-bands vary by pulsar, with some sub-bands achieving tens-to-hundreds of nanoseconds and others a few microseconds.
• Six binary pulsars and one solitary pulsar are newly included in DR3 compared with DR2.