Non-axisymmetrical deformations of the crust on rapidly rotating neutron
stars are one of the main targets of searches for continuous gravitational
waves. The maximum ellipticity, or fractional difference in moments of inertia,
that can be supported by deformations of the crust (known as “mountains”)
provides an important upper limit on the strength of these continuous
gravitational wave sources. We use the formalism of Gittins et al 2021, along
with a deforming force that acts mainly in the transverse direction, to obtain
a maximum ellipticity of 7.4$\times$10$^{-6}$. This is larger than the original
results of Gittins et al 2021 but consistent with earlier calculations by
Ushomirsky et al 2000. This suggests that rotating neutron stars could be
strong sources of continuous gravitational waves.
