Directed search for continuous gravitational waves from the possible kilonova remnant G4.8+6.2

Understand

G4.8+6.2 was proposed as a possible kilonova remnant associated with the Korean guest star of AD 1163 in our Milky Way galaxy.

• Its age is about 860 years according to the historical record.
• If a neutron star was left in the center of G4.8+6.2, this young neutron star may radiate strong continuous gravitational waves, which could beat the indirect age-based upper limit with current LIGO sensitivity.
• In this work, we searched such continuous gravitational waves in the frequency band $20-1500 \mathrm{~Hz}$.