Worldtube puncture scheme for first- and second-order self-force calculations in the Fourier domain

Second-order gravitational self-force theory has recently led to the breakthrough calculation of first post-adiabatic'' (1PA) compact-binary waveforms [Phys. Rev. Lett. 130, 241402 (2023)]. The computations underlying those waveforms depend on a method of solving the perturbative second-order Einstein equation on a Schwarzschild background in the Fourier domain. In this paper we present that method, which involves dividing the domain into several regions. Different regions utilize different time slicings and allow for the use of punctures’’ to tame sources and enforce physical boundary conditions. We demonstrate the method for Lorenz-gauge and Teukolsky equations in the relatively simple case of calculating parametric derivatives (``slow time derivatives’') of first-order fields, which are an essential input at second order.