Abstract:
Based on the X-ray observations from XMM–Newton and Swift, and optical observations from Transiting Exoplanet Survey
Satellite (TESS) and AAVSO, we present temporal and spectral properties of probable intermediate polar SWIFT J0503.7-2819.
The X-ray light curve shows two distinctive features, where possibly the second pole seems to be active during the middle
of the XMM–Newton observations. Present analysis confirms and also refines the previously reported orbital period of SWIFT
J0503.7-2819 as 81.65 ± 0.04 min. The X-ray and optical variations of this target have been found to occur at the period of
∼65 min, which we propose as the spin period of the white dwarf. The energy-dependent modulation at this period, which are
due to the photoelectric absorption in the accretion flow, also assures this conjecture. Two-temperature thermal plasma model
well explains the X-ray spectra with temperatures of ∼150 eV and ∼18.5 keV, which is absorbed by a dense material with an
average equivalent hydrogen column density of 3.8 × 1022 cm−2 that partially covers ∼27 per cent of the X-ray source. An
attempt is made to understand the accretion flow in this system using the present data of SWIFT J0503.7-2819. If the proposed
spin period is indeed the actual period, then SWIFT J0503.7-2819 could be the first nearly synchronous intermediate polar below
the period gap.
