Wide-band Timing of the Parkes Pulsar Timing Array UWL Data

Abstract

In 2018 an ultra–wide-bandwidth low-frequency (UWL) receiver was installed on the 64 m Parkes Radio Telescope, enabling observations with an instantaneous frequency coverage from 704 to 4032 MHz. Here we present the analysis of a 3 yr data set of 35 ms pulsars observed with the UWL by the Parkes Pulsar Timing Array, using wide-band timing methods. The two key differences compared to typical narrowband methods are (1) generation of two-dimensional templates accounting for pulse shape evolution with frequency and (2) simultaneous measurements of the pulse time of arrival (TOA) and dispersion measure (DM). This is the first time that wide-band timing has been applied to a uniform data set collected with a single large fractional bandwidth receiver, for which such techniques were originally developed. As a result of our study, we present a set of profile evolution models and new timing solutions, including initial noise analysis. Precision of our TOA and DM measurements is in the range of 0.005–2.08 μs and (0.043–14.24) × 10−4 cm−3 pc, respectively, with 94% of the pulsars achieving a median TOA uncertainty of less than 1 μs.

The International Pulsar Timing Array second data release: Search for an isotropic gravitational wave background

“…Figure 3). This feature was already reported in Tarafdar et al (2022) and is also shown in Curyło et al (2023) that used, respectively, the first data release of InPTA and the ultra-wide-bandwidth lowfrequency data from PPTA. Interestingly, we do not observe any associated impact on the RN posterior distributions.…”

The Gravitational-wave Background Null Hypothesis: Characterizing Noise in Millisecond Pulsar Arrival Times with the Parkes Pulsar Timing Array

“…We fit initial timing models using TEMPO2 (Edwards et al 2006), beginning from the timing analyses of the previous data releases (Reardon et al 2016(Reardon et al , 2021. For new pulsars added to the PPTA since the second data release (PPTA-DR2), we use the initial timing models from Curyło et al (2023). For four pulsars we required updates to the timing models.…”

The Parkes Pulsar Timing Array third data release

“…In the case of PSR J0437−4715, we first formed the invariant interval c (Britton 2000) of the profile prior to forming standard templates and hence ToAs. In this data release, we first followed the method presented by Pennucci et al (2014) to form wide-band profile portraits (Curyło et al 2023). We created one-dimensional templates for each channel across the eight sub-bands by evaluating the wide-band portrait model at the channel centre frequency.…”

“…We formed timing residuals initially using the timing ephemerides presented by Reardon et al (2021) and Curyło et al (2023), with the TT(BIPM2020) reference timescale published by the Bureau International des Poids et Mesures (BIPM) and the Jet Propulsion Laboratory Solar System ephemeris DE436. The wideband nature of the observations means that the ToA precision in each sub-band can vary with the scintillation state of the pulsar.…”

“…Key among these are the increased instantaneous sensitivity. Furthermore, UWL observations are excellent for measuring variations in pulse profiles across wide bandwidths (see Dai et al 2015), which has now been carefully accounted for using wide-band timing techniques (Pennucci, Demorest, & Ransom 2014Curyło et al 2023). The large instantaneous bandwidth also enables precise instantaneous measurements of dispersion measure (DM), and therefore its long-term variations, which is a key noise process to be accounted for in GW searches (Keith et al 2013;Cordes, Shannon, & Stinebring 2016).…”