Identifying fourINTEGRALsources in the Galactic plane via VLT/optical andXMM–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 H i and He i emission lines 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 O i emission signatures and the absence of narrow forbidden emission lines point towards a low-luminosity Seyfert 1.9 nature at z = 0.031 ± 0.002. Its XMM-Newton spectrum, best-fit by an absorbed Γ = 1.19 ± 0.07 power law combined with a z = 0.026−0.008 red-shifted iron emission feature, is in agreement with this classification. The likely IGR J17164−3803 optical counterpart is an M2III 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 F3V star that, if associated to IGR J19173+0747, likely belongs to a quiescent X-ray binary.

New hard X-ray sources discovered in the ongoing INTEGRAL Galactic plane survey after 14 yr of observations

“…Regular observations of the GP with INTEGRAL are consistently improving the sensitivity of the hard X-ray survey and allowing us to extend our knowledge of the Galactic Xray source population, both for weak and nearby sources (mostly CVs, see e.g. Lutovinov et al 2010;Clavel et al 2016;Tomsick et al 2016a), and more distant objects located at far end of the Galaxy Rahoui et al 2017). The presented catalogue opens the path to a large program of follow-up observations, dedicated both to unveil new classes of objects and to increase the overall completeness of the source sample, needed for many Galactic population studies.…”

“…In the previous paper (Krivonos et al 2012), we pre- Lutovinov et al 2013b, for details). A number of multi-wavelength follow-up observations were initiated to unveil the nature of these unclassified objects (Karasev et al 2012;Masetti et al 2013;Revnivtsev et al 2013;Zolotukhin & Revnivtsev 2015;Lutovinov et al 2013aLutovinov et al , 2015Tomsick et al 2015Tomsick et al , 2016aClavel et al 2016;Burenin et al 2016;Rahoui et al 2017) which led to the classification of 11 sources (shown by solid red circles in Fig. 1), rising the total survey identification completeness from ∼92% to ∼94%.…”

INTEGRAL view on Cataclysmic Variables and Symbiotic Binaries

“…After the aforementioned compilation by [114], [115] reported the first detection of the X-ray emission from eight more symbiotic systems using Swif t/XRT, thus bringing the total number of known symbiotic systems as X-ray sources to 33 (see also [38]). 561213) [120], IGR J17164-3803 [121] and IGR J17463-2854 [122].…”