Abstract: | We present a search for continuous gravitational waves from five radio
pulsars, comprising three recycled pulsars (PSR~J0437 extminus4715,
PSR~J0711 extminus6830, and PSR~J0737 extminus3039A) and two young pulsars:
the Crab pulsar (J0534+2200) and the Vela pulsar (J0835 extminus4510). We use
data from the third observing run of Advanced LIGO and Virgo combined with data
from their first and second observing runs. For the first time we are able to
match (for PSR~J0437 extminus4715) or surpass (for PSR~J0711 extminus6830)
the indirect limits on gravitational-wave emission from recycled pulsars
inferred from their observed spin-downs, and constrain their equatorial
ellipticities to be less than $10^{-8}$. For each of the five pulsars, we
perform targeted searches that assume a tight coupling between the
gravitational-wave and electromagnetic signal phase evolution. We also present
constraints on PSR~J0711 extminus6830, the Crab pulsar and the Vela pulsar
from a search that relaxes this assumption, allowing the gravitational-wave
signal to vary from the electromagnetic expectation within a narrow band of
frequencies and frequency derivatives. |