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We present an investigation of long-term modulation in the X-ray light curvesof five little-studied candidate high-mass X-ray binaries using the Swift BurstAlert Telescope. IGR J14488-5942 and AX J1700.2-4220 show strong modulation atperiods of 49.6 and 44 days, respectively, which are interpreted as orbitalperiods of Be star systems. For IGR J14488-5942, observations with Swift X-rayTelescope show a hint of pulsations at 33.4 s. For AX J1700.2-4220, 54 spulsations were previously found with XMM. Swift J1816.7-1613 exhibitscomplicated behavior. The strongest peak in the power spectrum is at a periodnear 150 days, but this conflicts with a determination of a period of 118.5days by La Parola et al. (2014). AX J1820.5-1434 has been proposed to exhibitmodulation near 54 days, but the extended BAT observations suggest modulationat slightly longer than double this at approximately 111 days. There appears tobe a long-term change in the shape of the modulation near 111 days, which mayexplain the apparent discrepancy. The X-ray pulsar XTE J1906+090, which waspreviously proposed to be a Be star system with an orbital period of ~30 daysfrom pulse timing, shows peaks in the power spectrum at 81 and 173 days. Theorigins of these periods are unclear, although they might be the orbital periodand a superorbital period respectively. For all five sources, the long-termvariability, together with the combination of orbital and proposed pulseperiods, suggests that the sources contain Be star mass donors.

Diverse Long-Term Variability of Five Candidate High-Mass X-ray Binaries from Swift Burst Alert Telescope Observations