CHIME-o-Grav: Wideband Timing of Four Millisecond Pulsars from the NANOGrav 15-yr dataset
Authors
Gabriella Agazie
David L. Kaplan
Abhimanyu Susobhanan
Ingrid H. Stairs
Deborah C. Good
Bradley W. Meyers
Emmanuel Fonseca
Timothy T. Pennucci
Akash Anumarlapudi
Anne M. Archibald
Zaven Arzoumanian
Paul T. Baker
Paul R. Brook
Alyssa Cassity
H. Thankful Cromartie
Kathryn Crowter
Megan E. DeCesar
Paul B. Demorest
Timothy Dolch
Fengqiu Adam Dong
Elizabeth C. Ferrara
William Fiore
Gabriel E. Freedman
Nate Garver-Daniels
Peter A. Gentile
Joseph Glaser
Jeffrey S. Hazboun
Ross J. Jennings
Megan L. Jones
Matthew Kerr
Michael T. Lam
Duncan R. Lorimer
Jing Luo
Ryan S. Lynch
Alexander McEwen
James W. McKee
Maura A. McLaughlin
Natasha McMann
Cherry Ng
David J. Nice
Benetge B. P. Perera
Nihan S. Pol
Henri A. Radovan
Scott M. Ransom
Paul S. Ray
Alexander Saffer
Ann Schmiedekamp
Carl Schmiedekamp
Brent J. Shapiro-Albert
Kevin Stovall
Joseph K. Swiggum
Mercedes S. Thompson
Haley M. Wahl
Abstract
Wideband timing of the North American Nanohertz Observatory for Gravitational Waves (NANOGrav) datasets, where a single time-of-arrival (TOA) and a single dispersion measure (DM) are measured using the entire bandwidth of each observation, was first done for the 12.5-year dataset, and proved to be invaluable for characterizing the time-varying dispersion measure, reducing the data volume, and for improving the overall timing precision. The Canadian Hydrogen Intensity Mapping Experiment (CHIME) Telescope has been observing most NANOGrav millisecond pulsars (MSPs) at nearly daily cadence (compared to roughly monthly cadence for other NANOGrav observations) since 2019 with the objective of integration into future pulsar timing array (PTA) datasets. In this paper, we show the results of integration of high-cadence, low-observing-frequency CHIME data with data from the NANOGrav experiment for an isolated MSP PSR J0645$+$5158 and three binary MSPs PSR J1012$+$5307, PSR J2145$-$0750, and PSR J2302$+$4442. Using a wideband timing pipeline which we also describe, we present updated timing results for all four sources, including improvements in measurements of relativistic post-Keplerian parameters for the three binary pulsars in this analysis. For PSR J2302$+$4442, we report an updated strong detection of Shapiro delay from which we measured a companion mass of $0.35^{+0.05}_{-0.04}\ M_{\odot}$, a pulsar mass of $1.8^{+0.3}_{-0.3}\ M_{\odot}$, and an orbital inclination of ${80^{\circ}}^{+1}_{-2}$. We also report updated constraints on the reflex motion for PSR J2145$-$0750 using a combination of Very Long Baseline Array astrometry and our updated measurement of the time derivative of the projected semi-major axis of the pulsar orbit as a prior.
