An intermediate polar candidate toward the Galactic plane

Context. For the past decade, it has been suggested that intermediate polars (IPs), a subclass of magnetic cataclysmic variables (CVs), are one of the main contributors to the hard di ff use X-ray emission from the Galactic center (GC) and Galactic ridge. Aims. In our ongoing XMM-Newton survey of the central region of the Galactic disk (20 ◦ × 2 ◦ ), we detected a persistent IP candidate, 1.7 ◦ away from the GC. In this work, we better characterize the behavior of this source by looking at the new and archival XMM- Newton data. Methods. We performed a detailed X-ray spectral modeling of the source. Furthermore, we searched for X-ray pulsations in the light curve as well as its counterpart at other wavelengths. Results. The XMM-Newton spectrum (0.8–10 keV) of the source is described by a partial covering collisionally ionized di ff use gas with plasma temperature kT = 15 . 7 + 20 . 9 − 3 . 6 keV. In addition, the spectrum shows the presence of iron lines at E = 6 . 44, 6.65, and 6.92 keV with equivalent widths of 194 + 89 − 70 , 115 + 79 − 75 , and 98 + 93 − 74 eV, respectively. The X-ray light curve shows a coherent modulation with a period of P = 432 . 44 ± 0 . 36 s, which we infer is the spin period of the white dwarf. The white dwarf mass estimated from fitting a physical model to the spectrum results in M WD = 1 . 05 + 0 . 16 − 0 . 21 M ⊙ . We were able to find a likely optical counterpart in the Gaia catalog with a G magnitude of 19.26, and the distance to the source derived from the measured Gaia parallax is ∼ 4.3 kpc. Conclusions. We provide an improved source localization with subarcsec accuracy. The spectral modeling of the source indicates the presence of intervening circumstellar gas, which absorbs the soft X-ray photons. The measured equivalent width of the iron lines and the detection of the spin period in the light curve are consistent with those from IPs.