Swift J201424.9+152930: Discovery of a new deeply eclipsing binary with 491-s and 3.4-h modulations

P. Esposito, G. L. Israel, D. de Martino, P. D'Avanzo, V. Testa, L. Sidoli, R. Di Stefano, A. Belfiore, M. Mapelli, S. Piranomonte, G. A. Rodríguez Castillo, A. Moretti, V. D'Elia, F. Verrecchia, S. Campana, N. Rea

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    Abstract

    © 2015 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society. 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 (N<inf>H</inf> ~ 5 × 10<sup>22</sup> cm<sup>-2</sup>) power law (Γ ~ 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.
    Original languageEnglish
    Pages (from-to)1705-1715
    JournalMonthly Notices of the Royal Astronomical Society
    Volume450
    Issue number2
    DOIs
    Publication statusPublished - 1 Jan 2015

    Keywords

    • Novae, cataclysmic variables
    • White dwarfs
    • X-rays: binaries
    • X-rays: individual: Swift J201424.9+152930

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