The NANOGrav 12.5 yr Data Set: Observations and Narrowband Timing of 47 Millisecond Pulsars

Abstract

We present a new analysis of the profile data from the 47 millisecond pulsars comprising the 12.5year data set of the North American Nanohertz Observatory for Gravitational Waves (NANOGrav), which is presented in a parallel paper (Alam et al. 2020, NG12.5). Our reprocessing is performed using "wideband" timing methods, which use frequency-dependent template profiles, simultaneous time-of-arrival (TOA) and dispersion measure (DM) measurements from broadband observations, and novel analysis techniques. In particular, the wideband DM measurements are used to constrain the DM portion of the timing model. We compare the ensemble timing results to NG12.5 by examining the timing residuals, timing models, and noise model components. There is a remarkable level of agreement across all metrics considered. Our best-timed pulsars produce encouragingly similar results to those from NG12.5. In certain cases, such as high-DM pulsars with profile broadening, or sources that are weak and scintillating, wideband timing techniques prove to be beneficial, leading to more precise timing model parameters by 10 − 15%. The high-precision, multi-band measurements of several pulsars indicate frequency-dependent DMs. Compared to the narrowband analysis in NG12.5, the TOA volume is reduced by a factor of 33, which may ultimately facilitate computational speed-ups for complex pulsar timing array analyses. This first wideband pulsar timing data set is a stepping stone, and its consistent results with NG12.5 assure us that such data sets are appropriate for gravitational wave analyses.

Noise analysis in the European Pulsar Timing Array data release 2 and its implications on the gravitational-wave background search

“…Several PTA collaborations are working actively on the detection and characterization of such GWs. The three historical PTAs: Parkes pulsar timing array (PPTA; Kerr et al 2020 ), the North American Nanohertz Observatory for Gra vitational-wa ves (NANOGra v; Alam et al 2021 ), and the European pulsar timing array (EPTA; Desvignes et al 2016 ) cooperate with the emerging Indian pulsar timing array (InPTA) 1 as the International pulsar timing array (IPTA; Verbiest et al 2016 ;Perera et al 2019 ). The PPTA, NANOGrav, and the EPTA have recently published results produced using with their own independently processed data sets that show consistent evidence for the presence of a red (time-correlated) signal common among pulsars (Arzoumanian et al 2020 ;Chen et al 2021 ;Goncharov et al 2021a ) but without the necessary evidence for Hellings-Downs correlations, which would confirm the detection of a GWB.…”

Multi-messenger Time-domain Signatures Of Supermassive Black Hole Binaries

“…The 11 yr dataset provides the most up-to-date upper limits on continuous waves, but the subsequent 12.5yr dataset has also become available(Alam et al 2021).MNRAS 000,1-15 (2021) …”

NICER Detection of Thermal X-Ray Pulsations from the Massive Millisecond Pulsars PSR J0740+6620 and PSR J1614–2230

“…These models are provided by ground-based pulsar timing programs at radio frequencies. PSR J0740+6620 is regularly observed as part of the NANOGrav pulsar timing program (Alam et al 2021) with the Green Bank Telescope (GBT), and also by the Canadian Hydrogen Intensity Mapping Experiment (CHIME). Fonseca et al (2021) have performed an analysis of these data, extending the work done by Cromartie et al (2020).…”

“…For PSR J1614−2230, we constructed a timing model using a merged data set from the NANOGrav 12.5 yr release (Alam et al 2021) and the Nançay radio telescope (NRT). The NRT data were obtained from MJD 57,424 (2016 February 6) through 58,921 (2020 March 13).…”