A tale of two magnetic CVs: TESS detection of QPOs and accretion variability in Swift J2113.5+5422, and the polar nature of LAMOST J003553.36+433341.4

We present long-term timing and spectral analyses of two magnetic cataclysmic variables: Swift J2113.5+5422 and LAMOST J003553.36+433341.4. Analysis of TESS photometry of Swift J2113.5+5422, spanning ∼5 yr, reveals orbital and spin periods of 3.6457734(21) hr and 1267.58196(36) s, respectively. A beat modulation between the spin and orbital signals is also detected at ∼1403 s, in excellent agreement with the predicted value. As the orbital and spin modulations remain phase-coherent throughout the observations, precise ephemerides for the times of pulse minima have been provided. Time-resolved power spectral analysis of Swift J2113.5+5422 suggests disc-overflow mode of accretion during most of the observations. However, there appear to be intervals during which pure disc-fed and stream-fed accretion could have occurred. Furthermore, we detect quasi-periodic oscillations (QPOs) between frequencies ∼ 20–37 cycles d−1 in two of the sectors, which can be explained using the diamagnetic blob accretion model where outward-spiralling blobs beat against the WD spin to produce these oscillations. For LAMOST J003553.36+433341.4, TESS photometry reveals an orbital period of 2.39640(24) hr, placing it well within the CV period gap. The LAMOST spectrum of the source is characterised by three prominent cyclotron humps which we model to derive a magnetic field strength of 51.8 ± 0.4 MG. Therefore, we conclude that LAMOST J003553.36+433341.4 is a polar-type magnetic CV.