Superradiance and black resonator strings encounter helical black strings

Understand

We construct a cohomogeneity-1 helical black string in six-dimensional Einstein gravity.

• The helical solution branches from the onset of the gravitational superradiant instability of the equal-spinning Myers-Perry black string.
• The isometry group of the helical black string is $\mathbb{R}_T \times U(1)_Z \times SU(2)$, where the first two are helical isometries generated by linear combinations of time translation, shifts along the string, and rotation, each of which is individually broken by the superradiant instability.
• The helical black string is stationary, non-axisymmetric, and has nonzero horizon velocity despite the absence of momentum in the string direction.