Setting the cornerstone for the IMRPhenomX family of models for
  gravitational waves from compact binaries: The dominant harmonic for
  non-precessing quasi-circular black holes
  In this paper we present IMRPhenomXAS, a thorough overhaul of the IMRPhenomD
[1,2] waveform model, which describes the dominant $l=2, \:| m | = 2$ spherical
harmonic mode of non-precessing coalescing black holes in terms of piecewise
closed form expressions in the frequency domain. Improvements include in
particular the accurate treatment of unequal spin effects, and the inclusion of
extreme mass ratio waveforms. IMRPhenomD has previously been extended to
approximately include spin precession [3] and subdominant spherical harmonics
[4], and with its extensions it has become a standard tool in gravitational
wave parameter estimation. Improved extensions of IMRPhenomXAS are discussed in
companion papers [5,6].
