Kavli Affiliate: Lijing Shao
| First 5 Authors: Garvin Yim, Yong Gao, Yacheng Kang, Lijing Shao, Renxin Xu
| Summary:
Gravitational waves from isolated sources have eluded detection so far. The
upper limit of long-lasting continuous gravitational wave emission is now at
the stage of probing physically-motivated models with the most optimistic being
strongly constrained. One potential avenue to remedy this is to relax the
assumption of the gravitational wave being quasi-infinite in duration, leading
to the idea of transient continuous gravitational waves. In this paper, we
outline how to get transient continuous waves from magnetars (or
strongly-magnetised neutron stars) that exhibit glitches and/or antiglitches.
We put forward a toy model whereby at a glitch or antiglitch, mass is ejected
from the magnetar but becomes trapped on its outward journey through the
magnetosphere. Depending on the specific values of the height of the trapped
ejecta and the magnetic inclination angle, we are able to reproduce both
glitches and antiglitches from simple angular momentum arguments. The trapped
ejecta sets the magnetar into precession causing gravitational waves to be
emitted at once and twice the magnetar’s spin frequency, for a duration equal
to however long the ejecta is trapped for. We find that the gravitational waves
are more likely to be detectable when the magnetar is: closer, rotating faster,
or has larger glitches/antiglitches. Specific to this model, we find that the
detectability improves when the ejecta height and magnetic inclination angle
have values near the boundary in the parameter space that separates glitches
and antiglitches, though this requires more mass to be ejected to remain
consistent with the observed glitch/antiglitch.
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