Chandra Observations of Eight Sources Discovered by INTEGRAL

Abstract

We report on 0.3-10 keV observations with the Chandra X-ray Observatory of eight hard X-ray sources discovered within 8 degrees of the Galactic plane by the INTEGRAL satellite. The short (5 ks) Chandra observations of the IGR source fields have yielded very likely identifications of X-ray counterparts for three of the IGR sources: IGR J14091-6108, IGR J18088-2741, and IGR J18381-0924. The first two have very hard spectra in the Chandra band that can be described by a power-law with photon indices of Gamma = 0.6+/-0.4 and -0.7(+0.4)(-0.3), respectively (90% confidence errors are given), and both have a unique near-IR counterpart consistent with the Chandra position. IGR J14091-6108 also displays a strong iron line and a relatively low X-ray luminosity, and we argue that the most likely source type is a Cataclysmic Variable (CV), although we do not completely rule out the possibility of a High Mass X-ray Binary. IGR J18088-2741 has an optical counterpart with a previously measured 6.84 hr periodicity, which may be the binary orbital period. We also detect five cycles of a possible 800-950 s period in the Chandra light curve, which may be the compact object spin period. We suggest that IGR J18088-2741 is also most likely a CV. For IGR J18381-0924, the spectrum is intrinsically softer with Gamma = 1.5(+0.5)(-0.4), and it is moderately absorbed, nH = (4+/-1)e22 cm-2. There are two near-IR sources consistent with the Chandra position, and they are both classified as galaxies, making it likely that IGR J18381-0924 is an Active Galactic Nucleus (AGN). For the other five IGR sources, we provide lists of nearby Chandra sources, which may be used along with further observations to identify the correct counterparts, and we discuss the implications of the low inferred Chandra count rates for these five sources.

Accepted by ApJ, 14 pages

References in corpus (10)

• The UKIRT Infrared Deep Sky Survey (UKIDSS)
• INTEGRAL/IBIS nine-year Galactic Hard X-Ray Survey
• Broadband X-ray Spectra of GX 339-4 and the Geometry of Accreting Black Holes in the Hard State
• Determining the covering factor of Compton-thick active galactic nuclei with NuSTAR
• IGR J17544-2619: A new supergiant fast X-ray transient revealed by optical/infrared observations
• An XMM-Newton view of FeKα in HMXBs
• Chandra Localizations and Spectra of INTEGRAL Sources in the Galactic Plane: The Cycle 9 Sample
• Properties of the Galactic population of cataclysmic variables in hard X-rays
• Chandra observations of five INTEGRAL sources: new X-ray positions for IGR J16393-4643 and IGR J17091-3624
• Chandra Identification of Two AGN Discovered by INTEGRAL

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• Identifying IGR J14091-6108 as a magnetic CV with a massive white dwarf using X-ray and optical observations
• Hard X-ray luminosity functions of cataclysmic variables: Joint Swift/BAT and Gaia data
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• Chandra Observations of High Energy X-ray Sources Discovered by INTEGRAL
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• NuSTAR observations of the unidentified INTEGRAL sources: constraints on the Galactic population of HMXBs
• Using Chandra Localizations and Gaia Distances and Proper Motions to Classify Hard X-ray Sources Discovered by INTEGRAL
• Optical Identification of X-ray Sources from the 14-Year INTEGRAL All-Sky Survey
• Identifying four $INTEGRAL$ sources in the Galactic Plane via VLT/optical and $XMM$-$Newton$/X-ray spectroscopy
• SRG/ART-XC Galactic Plane Survey near Galactic Longitude $l\simeq 20^{\circ }$: Catalog of Sources
• Optical Identification of Four Hard X-ray Sources from the INTEGRAL Sky Surveys
• Multi-wavelength observations of the Galactic X-ray binaries IGR J20155+3827 and Swift J1713.4-4219