Optical and X-Ray Investigations of Three Intermediate Polars: IGR J17040-4305, Swift J170800-402551.8, and AX J1832.3-0840

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Measuring the orbital periods and the beat periods between the spin and the orbital periods of magnetic cataclysmic variables is very important to understand their physical properties and evolutionary states. Based on long-term, high-precision optical data from TESS, this study performs a detailed time-variability analysis of three sources, IGR J17040-4305, Swift J170800-402551.8, and AX J1832.3-0840, and reanalyzes the XMM-Newton and NuSTAR observations. The power spectrum of the XMM-Newton data shows that the white dwarf spin period in IGR J17040-4305 is 957.44 ± 1.52 s. The TESS data further reveal its candidate orbital period and beat period to be 4.0821 ± 0.0008 hr and 1024.527 ± 0.011 s, respectively. For Swift J170800-402551.8, the NuSTAR FPMA data yield a candidate orbital period of 3.424 ± 0.059 hr, while the TESS data give a spin period of 783.64 ± 0.04 s and a candidate orbital period of 3.470 ± 0.002 hr. For AX J1832.3-0840, the TESS data measure the spin period, candidate orbital period, and beat period to be 1550.25 ± 0.09 s, 1.3838 ± 0.0003 hr, and 2251.11 ± 0.14 s, respectively. Based on the precise measurements of the candidate orbital periods of these three sources, their classification as intermediate polars is strongly supported. Furthermore, using the X-ray spectra from XMM-Newton and NuSTAR, the white dwarf masses of IGR J17040-4305 and Swift J170800-402551.8 are approximately estimated to be 0.774 ± 0.025 M ⊙ and 1.141 ± 0.062 M ⊙ , respectively.