IGR J14257-6117, a magnetic accreting white dwarf with a very strong strong X-ray orbital modulation

F. Bernardini, D. de Martino, K. Mukai, M. Falanga

    Research output: Contribution to journalArticlepeer-review


    IGR J14257-6117 is an unclassified source in the hard X-ray catalogues. Optical follow-ups suggest it could be a Cataclysmic Variable (CV) of the magnetic type. We present the first high signal-to-noise (S/N) X-ray observation performed by XMM-Newton at 0.3-10 keV, complemented with 10-80 keV coverage by Swift/BAT, aimed at revealing the source nature. We detected for the first time a fast periodic variability at 509.5 s and a longer periodic variability at 4.05 h, ascribed to the white dwarf (WD) spin and binary orbital periods, respectively. These unambiguously identify IGRJ14257-6117 as a magnetic CV of the intermediate polar (IP) type. The energy-resolved light curves at both periods reveal amplitudes decreasing with increasing energy, with the orbital modulation reaching ~100 per cent in the softest band. The energy spectrum shows optically thin thermal emission with an excess at the iron complex, absorbed by two dense media (NH ~ 1022-23 cm-2), partially covering the X-ray source. These are likely localized in the magnetically confined accretion flow above the WD surface and at the disc rim, producing the energy-dependent spin and orbital variabilities, respectively. IGR J14257-6117 joins the group of strongest orbitally modulated IPs now counting four systems. Drawing similarities with low-mass X-ray binaries displaying orbital dips, these IPs should be seen at large orbital inclinations allowing azimuthally extended absorbing material fixed in the binary frame to intercept the line of sight. For IGR J14257-6117, we estimate 50° ≲ i ≲ 70°.Whether also themass accretion rate plays a role in the large orbitalmodulations in IPs cannot be established with the present data.

    Original languageEnglish (US)
    Pages (from-to)1185-1192
    Number of pages8
    JournalMonthly Notices of the Royal Astronomical Society
    Issue number1
    StatePublished - Jul 21 2018


    • Cataclysmic variables
    • Novae
    • White dwarfs
    • X-rays: binaries
    • X-rays: individual: IGR J14257-6117 (aka 4PBC J1425.1-6118)

    ASJC Scopus subject areas

    • Astronomy and Astrophysics
    • Space and Planetary Science


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