X-ray properties of dwarf nova EY Cyg and the companion star using an XMM-Newton observation

Abstract

We present the X-ray analysis of dwarf nova EY Cyg using the 45 ks \textit{XMM-Newton} observatory archival data obtained in quiescence. We find orbital modulations in X-rays. We simultaneously fitted EPIC pn, MOS1 and MOS2 data using a model for interstellar medium absorption (\textit{tbabs}) and a multi-temperature plasma emission model with a power-law distribution of temperatures (CEVMKL) as expected from low accretion rate quiescent dwarf novae. The \textit{XMM-Newton} EPIC spectra of the source yields a maximum temperature $k{T}_{\max }$ $\sim$ 14.9${}_{-2.2}^{+3.3}$ keV with an unabsorbed X-ray flux and luminosity of (1.8--2.0) $\times$ 10${}^{-12}$ ergs${}^{-1}$ cm${}^{-1}$ and (8.7--9.7) $\times$ 10${}^{31}$ ergs${}^{-1}$, respectively, in the energy range 0.1 to 50 keV. There is 3--4 sigma excess at energies below 0.5 keV, we model the excess using \textit{MEKAL}, POWERLAW and BBODY models and favor the model \textit{MEKAL} which is physical. According to previous studies, the secondary in this system is thought to be a K-type star which may radiate in the soft X-ray region. The fit with an additive \textit{MEKAL} model gives a temperature of $kT$ $\sim$ 0.1 keV with an unabsorbed X-ray flux and luminosity of (2.7--8.8) $\times$ 10${}^{-14}$ ergs${}^{-1}$ cm${}^{-1}$ and (1.3--4.2) $\times$ 10${}^{30}$ ergs${}^{-1}$, respectively, for the companion star. Based on the results from the timing and spectral analysis, we highly suggest that the secondary of EY Cyg is a K-type star.

7 pages, 3 figures, 3 tables. Accepted for publication in a Special Issue of Advances in Space Research, entitled "Nova Eruptions, Cataclysmic Variables and Related Systems: observational vs theoretical challenges in the 2020 era", edited BY S. Balman and P. A. Shea

References in corpus (6)

• Cross-Calibration of the XMM-Newton EPIC pn & MOS On-Axis Effective Areas Using 2XMM Sources
• SWIFT XRT Observations of the Nova-like Cataclysmic Variables MV Lyr, BZ Cam and V592 Cas
• Determination of the basic parameters of the dwarf nova EY Cygni
• Chandra HETG line spectroscopy of the Non-magnetic Cataclysmic Variable SS Cyg
• X-ray Spectral Variations of U Gem from Quiescence to Outburst
• Pre-outburst $Chandra$ Observations of the Recurrent Nova T Pyxidis

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• Confirmation of SRGt 062340.2-265751 as a nova-like cataclysmic variable with a possible magnetic nature