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arXiv · 2405.01996

Optical spectroscopic and photometric classification of the X-ray transient EP240309a (EP J115415.8-501810) as an intermediate polar

Stephen. B. Potter·David A. H. Buckley·S. Scaringi·I. M. Monageng·Okwudili D. Egbo·Philip A. Charles·N. Erasmus·Carel van Gend·Egan Loubser·Keegan Titus·Kathryn Rosie·Hitesh Gajjar·H. L. Worters·Sunil Chandra·R. P. M. Julie·Moloko Hlakola
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Abstract

We report on optical follow-up observations of an X-ray source initially detected by the Einstein Probe mission. Our investigations categorize the source as an intermediate polar, a class of magnetic cataclysmic variables, exhibiting an orbital period of 3.7614(4) hours and a white dwarf spin period of 3.97 minutes. The orbital period was identified through TESS observations, while our high-speed photometric data, obtained using the 1.9m and Lesedi 1.0m telescopes at the South African Astronomical Observatory, revealed both the spin and beat periods. Additionally, we present orbitally phase-resolved spectroscopic observations using the 1.9m telescope, specifically centered on the Hbeta emission line, which reveal two emission components that exhibit Doppler variations throughout the orbital cycle.

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Stephen. B. Potter, David A. H. Buckley, S. Scaringi, I. M. Monageng, Okwudili D. Egbo, Philip A. Charles, N. Erasmus, Carel van Gend, Egan Loubser, Keegan Titus, Kathryn Rosie, Hitesh Gajjar, H. L. Worters, Sunil Chandra, R. P. M. Julie, Moloko Hlakola. 2024-05-03. Optical spectroscopic and photometric classification of the X-ray transient EP240309a (EP J115415.8-501810) as an intermediate polar. https://arxiv.org/abs/2405.01996

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