Esposito, P., Israel, G. L., de Martino, D., D'Avanzo, P., Testa, V., Sidoli, L., Di Stefano, R., Belfiore, A., Mapelli, M., Piranomonte, S., Rodríguez Castillo, G. A., Moretti, A., D'Elia, V., Verrecchia, F., Campana, S. and Rea, N.
Abstract
We report on the discovery of a new X-ray pulsator, Swift J201424.9 152930 (Sw J2014). Owing to its X-ray modulation at 491 s, it was discovered in a systematic search for coherent signals in the archival data of the Swift X-ray Telescope. To investigate the nature of Sw J2014, we performed multiwavelength follow-up observations with space-borne (Swift and XMM-Newton) and ground-based (the 1.5-m Loiano Telescope and the 3.6-m Telescopio Nazionale Galileo) instruments. The X-ray spectrum of Sw J2014 can be described by a hard and highly absorbed (NH ˜ 5 × 1022 cm-2) power law (G ˜ 1). The optical observations made it possible to single out the optical counterpart to this source, which displays several variable emission lines and total eclipses lasting ˜20 min. Total eclipses of similar length were observed also in X-rays. The study of the eclipses, allowed us to infer a second periodicity of 3.44 h, which we interpret as the orbital period of a close binary system. We also found that the period has not significantly changed over a ˜7 yr timespan. Based on the timing signatures of Sw J2014, and its optical and X-ray spectral properties, we suggest that it is a close binary hosting an accreting magnetic white dwarf. The system is therefore a cataclysmic variable of the intermediate polar type and one of the very few showing deep eclipses.
