Swift unveils the orbital period of IGR J18214-1318

Abstract

We analysed 13 years of the Neil Gehrels Swift Observatory survey data collected on the High Mass X-ray Binary IGR J18214-1318. Performing the timing analysis we detected a periodic signal of 5.42 d. From the companion star characteristics we derived an average orbital separation of $\sim 41{\mathrm{R}}_{\odot }\simeq 2{\mathrm{R}}_{\star }$. The spectral type of the companion star (O9) and the tight orbital separation suggest that IGR~J18214-1318 is a wind accreting source with eccentricity lower than 0.17. The intensity profile folded at the orbital period shows a deep minimum compatible with an eclipse of the source by the companion star. In addition, we report on the broad-band 0.6--100 keV spectrum using data from XMM-Newton, NuSTAR, and Swift, applying self-consistent physical models. We find that the spectrum is well fitted either by a pure thermal Comptonization component, or, assuming that the source is a neutron star accreting above the critical regime, by a combined thermal and bulk-motion Comptonization model. In both cases, the presence of a local neutral absorption (possibly related to the thick wind of the companion star) is required.

7 pages, 7 figures. Accepted by MNRAS on 2020-08-17

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Cited by in corpus (3)

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• INTEGRAL/IBIS 17-yr hard X-ray all-sky survey
• SRG/ART-XC Galactic Plane Survey near Galactic Longitude $l\simeq 20^{\circ }$: Catalog of Sources