The MeerTime Pulsar Timing Array: A census of emission properties and timing potential

Abstract

MeerTime is a five-year Large Survey Project to time pulsars with MeerKAT, the 64-dish South African precursor to the Square Kilometre Array. The science goals for the programme include timing millisecond pulsar (MSPs) to high precision ( ${<} 1 \unicode{x03BC} \mathrm{s}$ ) to study the Galactic MSP population and to contribute to global efforts to detect nanohertz gravitational waves with the International Pulsar Timing Array (IPTA). In order to plan for the remainder of the programme and to use the allocated time most efficiently, we have conducted an initial census with the MeerKAT ‘L-band’ receiver of 189 MSPs visible to MeerKAT and here present their dispersion measures, polarisation profiles, polarisation fractions, rotation measures, flux density measurements, spectral indices, and timing potential. As all of these observations are taken with the same instrument (which uses coherent dedispersion, interferometric polarisation calibration techniques, and a uniform flux scale), they present an excellent resource for population studies. We used wideband pulse portraits as timing standards for each MSP and demonstrated that the MeerTime Pulsar Timing Array (MPTA) can already contribute significantly to the IPTA as it currently achieves better than $1\,\unicode{x03BC}\mathrm{s}$ timing accuracy on 89 MSPs (observed with fortnightly cadence). By the conclusion of the initial five-year MeerTime programme in 2024 July, the MPTA will be extremely significant in global efforts to detect the gravitational wave background with a contribution to the detection statistic comparable to other long-standing timing programmes.

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

“…Similarly, subtle profile shape characteristics and its changes can be lost for models with only one eigenprofile, especially in the upper part of the band, where the flux of most pulsars is usually lower. Two extreme examples of such sources are J0030+0451 and J2129−5721, both with large spectral indices, α J0030 = − 2.4 and α J2129 = − 3.9, respectively (Spiewak et al 2022). In order to capture any profile evolution and more accurately predict the pulse shapes at lower frequencies, we decided to remove the upper part of the band above 3000-3500 MHz.…”

The MeerKAT Pulsar Timing Array: first data release

“…It is important to note that while the sensitivity of a PTA to the SGWB increases strongly with the length of the data span, it is also directly proportional to the number of pulsars in the array (Siemens et al 2013). As noted in Spiewak et al (2022), the inclusion of the MPTA and its otherwise unobserved pulsars, results in the MPTA potentially becoming the most significant contributor to IPTA searches for the SGWB by 2025, unless cadences or sensitivities at the other PTAs change. In addition, there is work currently underway investigating improvements to the MPTA, potentially resulting in a more aggressive timeline for improved sensitivity (Middleton et al, in prep.…”

“…This provides approximately 2.5 years of data for the majority of the pulsars included in the MPTA. The full MPTA includes 88 pulsars, which have been selected from a census of 189 MSPs visible to MeerKAT (Spiewak et al 2022). The pulsars were initially chosen to obtain a band averaged timing precision of < 1𝜇s within an integration time of 1000 seconds.…”

“…Millisecond pulsar timing with MeerKAT (The MeerKAT Pulsar Timing Array 2 , MPTA), is undertaken as part of the MeerTime Large Survey Project (LSP) (Bailes et al 2016). The potential of the MeerKAT PTA project has already been demonstrated through dedicated studies of jitter noise in the MSP population (Parthasarathy et al 2021), a comprehensive census of the MSPs visible to MeerKAT and their emission properties (Spiewak et al 2022), and the discovery of mode-changing in one of the most precisely timed and often observed millisecond pulsars (Miles et al 2022).…”

“…In addition to this high sensitivity MeerKAT's ability to quickly slew between sources and the access it has to a large swathe of pulsars (Dec < +44 • ), makes the MPTA naturally suited to contribute to the IPTA through high precision timing of a large array of pulsars. Forecasts show that the MeerKAT PTA will be contributing roughly half of the IPTA sensitivity by 2025 with current target lists and cadences (Spiewak et al 2022).…”