The NANOGrav 15 yr and 20 yr Datasets: Timing Events and Pulse Shape Changes
Abstract
The average pulse shape of a pulsar is typically stable over decadal timescales, enabling estimation of pulse times of arrival to better than a small fraction of the pulse width using matched filtering techniques. However, in North American Nanohertz Observatory for Gravitational Waves (NANOGrav) observations of PSR J1713+0747, three discrete timing events that depart from the prevailing timing model have been seen in the last 20 yr. All three correspond to morphological changes in pulse shape. Using principal component analysis, we analyze the pulse profiles of nine NANOGrav pulsars, including seven with profiles from the 15 yr dataset and two with additional profiles from the forthcoming 20 yr dataset. We recover the three known pulse shape change events in PSR J1713+0747 and another previously known event in PSR J16431224. We implement a ranking metric for candidate events and address four highly ranked candidates in this nine-pulsar sample. We also recover known slow pulse shape variations in PSR J16431224, PSR J1903+0327, and PSR B1937+21 and report an unexpected recurrence after ~10 yr of one such variation in PSR B1937+21.
Keywords
Cite
@article{arxiv.2604.05453,
title = {The NANOGrav 15 yr and 20 yr Datasets: Timing Events and Pulse Shape Changes},
author = {Ben Jacobson-Bell and James M. Cordes and Shami Chatterjee and Sashabaw Niedbalski and Gabriella Agazie and Akash Anumarlapudi and Anne M. Archibald and Zaven Arzoumanian and Jeremy G. Baier and Paul T. Baker and Paul R. Brook and H. Thankful Cromartie and Kathryn Crowter and Megan E. DeCesar and Paul B. Demorest and Lankeswar Dey and Timothy Dolch and Elizabeth C. Ferrara and William Fiore and Emmanuel Fonseca and Gabriel E. Freedman and Nate Garver-Daniels and Peter A. Gentile and Joseph Glaser and Deborah C. Good and Jeffrey S. Hazboun and Ross J. Jennings and Megan L. Jones and David L. Kaplan and Matthew Kerr and Michael T. Lam and Bjorn Larsen and Duncan R. Lorimer and Georgia A. Lowes and Jing Luo and Ryan S. Lynch and Ashley Martsen and Alexander McEwen and Maura A. McLaughlin and Natasha McMann and Bradley W. Meyers and Patrick M. Meyers and Cherry Ng and Mason Ng and David J. Nice and Shania Nichols and Daniel J. Oliver and Timothy T. Pennucci and Benetge B. P. Perera and Nihan S. Pol and Henri A. Radovan and Scott M. Ransom and Paul S. Ray and Alexander Saffer and Ann Schmiedekamp and Carl Schmiedekamp and Brent J. Shapiro-Albert and Ingrid H. Stairs and Kevin Stovall and Abhimanyu Susobhanan and Joseph K. Swiggum and Mercedes S. Thompson and Amir Tresnjic and Haley M. Wahl},
journal= {arXiv preprint arXiv:2604.05453},
year = {2026}
}
Comments
27 pages, 3 tables, 18 figures incl. 3 figure sets in ancillary files. Submitted to ApJ