Search for continuous gravitational waves from PSR <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mi mathvariant="normal">J</mml:mi><mml:mn>0437</mml:mn><mml:mtext>−</mml:mtext><mml:mn>4715</mml:mn></mml:mrow></mml:math> with a hidden Markov model in O3 LIGO data

Results are presented for a semicoherent search for continuous gravitational waves from the millisecond pulsar PSR $\mathrm{J}0437\text{\ensuremath{-}}4715$, using a hidden Markov model to track spin wandering, in LIGO data from the third LIGO-Virgo observing run. This is the first search for PSR $\mathrm{J}0437\text{\ensuremath{-}}4715$ to cover a wide frequency range from 60 to 500 Hz and simultaneously accommodate random spin deviations from the secular radio ephemeris. Two searches are performed with plausible coherence times of 10 and 30 days, as the frequency wandering time scale of the gravitational-wave-emitting quadrupole is unknown. The former analysis yields no surviving candidates, while the latter yields five candidates after the veto procedure. The detection statistic of each of the five survivors is mapped as a function of sky position, in preparation for follow-up analyses in the future, e.g., during the LIGO-Virgo-KAGRA fourth observing run.