Abstract Discovering radio pulsars in compact binaries, whose orbital periods P b satisfy P b ≲ 1 day, is computationally challenging, because the time-dependent pulse frequency f p ( t ) is strongly Doppler modulated by the binary motion. Here we present a new, fast, semi-coherent detection scheme based on a hidden Markov model (HMM) combined with a maximum-likelihood matched filter, the Schuster periodogram. The HMM scheme complements traditional acceleration searches by dividing f p ( t ) into piecewise-constant blocks and tracking the block-to-block evolution efficiently using dynamic programming. Monte Carlo simulations show that the new method can detect compact binaries with flux densities S ≥ 0.50 mJy and orbital periods P b ≥ 0.012 day under observing conditions (e.g., cadence) typical of radio pulsar surveys, with and without impulsive, narrowband radio-frequency interference. The new method is fast; it employs the classic Viterbi algorithm to solve the HMM recursively. The central processing unit runtime scales nominally as T run ≈ 2.8 N B ( N T / 1 0 2 ) ( N Q ln N Q / 1 0 4 ln 1 0 4 ) s for N B subbands, N T coherent segments, and N Q frequency bins.
O’Leary et al. (Mon,) studied this question.