Identifying four $INTEGRAL$ sources in the Galactic Plane via VLT/optical and $XMM$-$Newton$/X-ray spectroscopy

Abstract

We report on FORS2 spectroscopy aiming at the identification of four Galactic Plane sources discovered by $INTEGRAL$, IGR J18088-2741, IGR J18381-0924, IGR J17164-3803, and IGR J19173+0747, complemented by $XMM$-$Newton$ spectroscopy for IGR J18381-0924. The presence of broad emission lines of neutral H and He and a flat Balmer decrement Hα/Hβ show that IGR J18088-2741 is a cataclysmic variable located beyond 8 kpc. For IGR J18381-0924, the detection of red-shifted Hα and neutral O emission signatures and the absence of narrow forbidden emission lines point towards a low-luminosity Seyfert 1.9 nature at $z=0.031\pm 0.002$. Its $XMM$-$Newton$ spectrum, best-fit by an absorbed $\Gamma =1.19\pm 0.07$ power law combined with a $z=0.026_{-0.016}^{+0.008}$ red-shifted iron emission feature, is in agreement with this classification. The likely IGR J17164-3803 optical counterpart is an M2 III star at 3 to 4 kpc which, based on the X-ray spectrum of the source, is the companion of a white dwarf in an X-ray faint symbiotic system. Finally, we challenge the accepted identification of IGR J19173+0747 as an high mass X-ray binary. Indeed, the USNO optical counterpart is actually a blend of two objects located at the most likely 3 kpc distance, both lying within the error circle of the Swift position. The first is a cataclysmic variable, which we argue is the real nature of IGR J19173+0747. However, we cannot rule out the second one that we identify as an F3 V star that, if associated to IGR J19173+0747, likely belongs to a quiescent X-ray binary.

10 pages, 8 figures, 4 tables. Accepted for publication in MNRAS

References in corpus (15)

• The UKIDSS Galactic Plane Survey
• X-Ray Spectroscopy of Stars
• Swift monitoring of NGC 5548: X-ray reprocessing and short term UV/optical variability
• Multi-wavelength observations of Galactic hard X-ray sources discovered by INTEGRAL. I. The nature of the companion star
• Multi-wavelength observations of Galactic hard X-ray sources discovered by INTEGRAL. II. The environment of the companion star
• INTEGRAL/IBIS nine-year Galactic Hard X-Ray Survey
• Chandra Localizations and Spectra of INTEGRAL Sources in the Galactic Plane
• Observations of OI and CaII Emission Lines in Quasars: Implications for the Site of FeII Line Emission
• IGR J18483-0311: a new intermediate supergiant fast X-ray transient
• On the distance of GRO J1655-40
• Discovery of X-ray emission from the first Be/black hole system
• Chandra observations of five INTEGRAL sources: new X-ray positions for IGR J16393-4643 and IGR J17091-3624
• The Norma Arm Region Chandra Survey: X-ray Populations in the Spiral Arms
• AX J1910.7+0917 and three newly discovered INTEGRAL sources
• Near-infrared spectroscopy of 20 new Chandra sources in the Norma Arm

Cited by in corpus (4)

• INTEGRAL/IBIS 17-yr hard X-ray all-sky survey
• INTEGRAL view on Cataclysmic Variables and Symbiotic Binaries
• NuSTAR observations of the unidentified INTEGRAL sources: constraints on the Galactic population of HMXBs
• Update of the INTEGRAL/IBIS AGN catalogue: deeper on the Galactic plane and wider beyond