Abbott, R.Abbott, T. D.Acernese, F.Ackley, K.Adams, C.Adhikari, N.Adhikari, R. X.Adya, VaishaliAffeldt , C.Agarwal, D.Agathos, M.Aggarwal, NAgatsuma, KAltin, PaulChua, SheonEichholz, JohannesForsyth, PerryGould, DanielGrace, BenjaminJunker, JonasKapasi, DishaKijbunchoo, NutsineeMcClelland, DavidMcRae, TerryScott, SusanSlagmolen, BramSun, LingWard, RobertWette, KarlYap, Min JetZhang, Jue2026-01-122026-01-120004-637Xhttps://hdl.handle.net/1885/733804020Isolated neutron stars that are asymmetric with respect to their spin axis are possible sources of detectable continuous gravitational waves. This paper presents a fully coherent search for such signals from eighteen pulsars in data from LIGO and Virgo's third observing run (O3). For known pulsars, efficient and sensitive matched-filter searches can be carried out if one assumes the gravitational radiation is phase-locked to the electromagnetic emission. In the search presented here, we relax this assumption and allow both the frequency and the time derivative of the frequency of the gravitational waves to vary in a small range around those inferred from electromagnetic observations. We find no evidence for continuous gravitational waves, and set upper limits on the strain amplitude for each target. These limits are more constraining for seven of the targets than the spin-down limit defined by ascribing all rotational energy loss to gravitational radiation. In an additional search, we look in O3 data for long-duration (hours-months) transient gravitational waves in the aftermath of pulsar glitches for six targets with a total of nine glitches. We report two marginal outliers from this search, but find no clear evidence for such emission either. The resulting duration-dependent strain upper limits do not surpass indirect energy constraints for any of these targets.We acknowledge support from EPSRC/STFC fellowship (EP/T017325/1), ANID/FONDECYT grants 1171421 and 1211964, and NASA grants 80NSSC19K1444 and 80NSSC21K0091. This work is supported by NASA through the NICER mission and the Astrophysics Explorers Program, and uses data and software provided by the High Energy Astrophysics Science Archive Research Center (HEASARC), which is a service of the Astrophysics Science Division at NASA/GSFC and High Energy Astrophysics Division of the Smithsonian Astrophysical Observatory. CHIME is funded by a grant from the Canada Foundation for Innovation (CFI) 2012 Leading Edge Fund (Project 31170) and by contributions from the provinces of British Columbia, Québec, and Ontario. The CHIME/FRB Project, which enabled development in common with the CHIME/Pulsar instrument, is funded by a grant from the CFI 2015 Innovation Fund (Project 33213) and by contributions from the provinces of British Columbia and Québec, and by the Dunlap Institute for Astronomy and Astrophysics at the University of Toronto. Additional support was provided by the Canadian Institute for Advanced Research (CIFAR), McGill University, and the McGill Space Institute thanks to the Trottier Family Foundation, and the University of British Columbia. The CHIME/Pulsar instrument hardware was funded by NSERC RTI-1 grant EQPEQ 458893-2014. This research was enabled in part by support provided by WestGrid ( www.westgrid.ca ) and Compute Canada ( www.computecanada.ca ). We acknowledge support from the Natural Sciences and Engineering Research Council of Canada (NSERC) funding reference #CITA 490888-16, the Canadian Institute for Advanced Research, and the UBC Four Year Fellowship (6456). This work was supported by MEXT, JSPS Leading-edge Research Infrastructure Program, JSPS Grant-in-Aid for Specially Promoted Research 26000005, JSPS Grant-in-Aid for Scientific Research on Innovative Areas 2905: JP17H06358, JP17H06361 and JP17H06364, JSPS Core-to-Core Program A. Advanced Research Networks, JSPS Grant-in-Aid for Scientific Research (S) 17H06133 and 20H05639, JSPS Grant-in-Aid for Transformative Research Areas (A) 20A203: JP20H05854, the joint research program of the Institute for Cosmic Ray Research, University of Tokyo, National Research Foundation (NRF), Computing Infrastructure Project of KISTI-GSDC, Korea Astronomy and Space Science Institute (KASI), and Ministry of Science and ICT (MSIT) in Korea, Academia Sinica (AS), AS Grid Center (ASGC) and the Ministry of Science and Technology (MoST) in Taiwan under grants including AS-CDA-105-M06, Advanced Technology Center (ATC) of NAOJ, and Mechanical Engineering Center of KEK.application/pdfen-AU© 2022 The Author(s)https://creativecommons.org/licenses/by/4.0/202210.3847/1538-4357/ac6ad02023-10-22Creative Commons Attribution 4.0 licence