An XMM-Newton and NuSTAR study of IGR J18214-1318: a non-pulsating high-mass X-ray binary with a neutron star

Abstract

IGR J18214-1318, a Galactic source discovered by the International Gamma-Ray Astrophysics Laboratory, is a high-mass X-ray binary (HMXB) with a supergiant O-type stellar donor. We report on the XMM-Newton and NuSTAR observations that were undertaken to determine the nature of the compact object in this system. This source exhibits high levels of aperiodic variability, but no periodic pulsations are detected with a 90% confidence upper limit of 2% fractional rms between 0.00003-88 Hz, a frequency range that includes the typical pulse periods of neutron stars (NSs) in HMXBs (0.1-10${}^3$ s). Although the lack of pulsations prevents us from definitively identifying the compact object in IGR J18214-1318, the presence of an exponential cutoff with e-folding energy $\lesssim 30$ keV in its 0.3-79 keV spectrum strongly suggests that the compact object is an NS. The X-ray spectrum also shows a Fe K$\alpha$ emission line and a soft excess, which can be accounted for by either a partial-covering absorber with $N_{\mathrm{H}}\approx 10^{23}$ cm${}^{-2}$ which could be due to the inhomogeneous supergiant wind, or a blackbody component with $kT=1.74_{-0.05}^{+0.04}$ keV and $R_{BB}\approx 0.3$ km, which may originate from NS hot spots. Although neither explanation for the soft excess can be excluded, the former is more consistent with the properties observed in other supergiant HMXBs. We compare IGR J18214-1318 to other HMXBs that lack pulsations or have long pulsation periods beyond the range covered by our observations.

15 pages, 12 figures, 4 tables

References in corpus (27)

• Thermal and Bulk Comptonization in Accretion-Powered X-Ray Pulsars
• Unveiling supergiant fast X-ray transient sources with INTEGRAL
• Multi-wavelength observations of Galactic hard X-ray sources discovered by INTEGRAL. I. The nature of the companion star
• No Time for Dead Time: Timing analysis of bright black hole binaries with NuSTAR
• INTEGRAL/IBIS nine-year Galactic Hard X-Ray Survey
• A 0535+26 in the August/September 2005 outburst observed by RXTE and INTEGRAL
• Unveiling the nature of six HMXBs through IR spectroscopy
• Bright Flares in Supergiant Fast X-ray Transients
• On the metallicity dependence of HMXBs
• Effects of the stellar wind on X-ray spectra of Cygnus X-3
• Chandra Localizations and Spectra of INTEGRAL Sources in the Galactic Plane
• NuSTAR Detection Of A Cyclotron Line In The Supergiant Fast X-ray Transient IGR J17544-2619
• Discovery of slow X-ray pulsations in the high-mass X-ray binary 4U 2206+54
• A broadband X-ray study of the Geminga pulsar with NuSTAR and XMM-Newton
• XMM-Newton observation of the Be/neutron star system RX J0146.9+6121: a soft X-ray excess in a low luminosity accreting pulsar
• XMM-Newton observation of the persistent Be/neutron-star system X Persei at a high-luminosity level
• Spectral and Timing Nature of the Symbiotic X-ray Binary 4U 1954+319: The Slowest Rotating Neutron Star in an X-ray Binary System
• NuSTAR Discovery of a Cyclotron Line in the Be/X-ray Binary RX J0520.5-6932 During Outburst
• Further evidence for the presence of a neutron star in 4U 2206+54. INTEGRAL and VLA observations
• Optical/infrared observations unveiling the formation, nature and evolution of High-Mass X-ray Binaries
• Confirmation of a High Magnetic Field in GRO J1008-57
• A Possible Magnetar Nature for IGR J16358-4726
• Swift follow-up observations of 17 INTEGRAL sources of uncertain or unknown nature
• Peering through the stellar wind of IGR J19140+0951 with simultaneous INTEGRAL/RXTE observations
• The XMM-Newton/INTEGRAL monitoring campaign of IGR J16318-4848
• The nature of the infrared counterpart of IGR J19140+0951
• Broadband Suzaku observations of IGR J16207-5129

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• SRG/ART-XC Galactic Plane Survey near Galactic Longitude $l\simeq 20^{\circ }$: Catalog of Sources
• Swift unveils the orbital period of IGR J18214-1318
• Spectral and Timing properties of the recently discovered Be/X-ray pulsar eRASSUJ 052914.9-662446