Identifications of five INTEGRAL sources via optical spectroscopy

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Official URL: http://dx.doi.org/10.1088/0004-637X/698/1/502

The International Gamma-Ray Astrophysics Laboratory (INTEGRAL) is discovering hundreds of new hard X-ray sources, many of which remain unidentified. We report on optical spectroscopy of five such sources for which X-ray observations at lower energies (similar to 0.5-10 keV) and higher angular resolutions than INTEGRAL have allowed for unique optical counterparts to be located. We find that INTEGRAL Gamma-Ray (IGR) J16426+6536 and IGR J22292+6647 are Type 1 Seyfert active galactic nuclei (with IGR J16426+6536 further classified as a Seyfert 1.5) which have redshifts of z = 0.323 and z = 0.113, respectively. IGR J18308-1232 is identified as a cataclysmic variable (CV), and we confirm a previous identification of IGR J19267+1325 as a magnetic CV. IGR J18214-1318 is identified as an obscured high-mass X-ray binary (HMXB), which are systems thought to have a compact object embedded in the stellar wind of a massive star. We combine Chandra fluxes with distances based on the optical observations to calculate X-ray luminosities of the HMXB and CVs, finding L0.3-10 (keV) = 5 x 10(36) erg s(-1) for IGR J18214-1318, L0.3-10 keV = 1.3 x 10(32) erg s(-1) for IGR J18308-1232, and L0.3-10 keV = 6.7 x 10(32) erg s(-1) for IGR J19267+1325.