The Fe Line Flux Ratio as a diagnostic of the maximum temperature and the white dwarf mass of Cataclysmic Variables

Abstract

The flux ratio of Fe XXVI--Ly$\alpha$ to Fe XXV--He$\alpha$ lines ($I_{7.0}/I_{6.7}$) is a sensitive indicator of the maximum temperature ($T_{\max }$), and therefore the mass of white dwarf stars ($M_{\mathrm{WD}}$) in cataclysmic variables (CVs). To examine and calibrate the theoretical $I_{7.0}/I_{6.7}$--$T_{\max }$--$M_{\mathrm{WD}}$ relations, reliable measurements of $T_{\max }$ and $I_{7.0}/I_{6.7}$ are necessary. In this work, we conduct a thorough investigation on 3--50 keV X-ray spectra of 25 solar neighborhood magnetic and non-magnetic CVs based on archival \textit{NuSTAR} and \textit{Suzaku} observations. The measured $T_{\max }$ are compared to the $I_{7.0}/I_{6.7}$ and $M_{\mathrm{WD}}$. The results show the sampled CVs closely follow the theoretical $I_{7.0}/I_{6.7}$--$T_{\max }$ relation. Moreover, all the $M_{\mathrm{WD}}$ estimated from $I_{7.0}/I_{6.7}$ are consistent with the dynamically measured ones. We conclude that $I_{7.0}/I_{6.7}$ can be used as a good diagnostic for $T_{\max }$ and $M_{\mathrm{WD}}$ in both magnetic and non-magnetic CVs.

arXiv comment15 pages, 4 figures, Accepted for publication in ApJ

References in corpus (22)

• The Nuclear Spectroscopic Telescope Array (NuSTAR) Mission
• Catalogue of cataclysmic binaries, low-mass X-ray binaries and related objects (Seventh edition)
• Hard X-ray Detector (HXD) on Board Suzaku
• X-ray Emissions from Accreting White Dwarfs: a Review
• X-ray luminosity function of faint point sources in the Milky Way
• Two Types of X-ray Spectra in Cataclysmic Variables
• RXTE broadband X-ray spectra of intermediate polars and white dwarf mass estimates
• Hard X-ray view on intermediate polars in the Gaia era
• Deriving an X-ray luminosity function of dwarf novae based on parallax measurements
• The space density of magnetic cataclysmic variables
• Fe Line Diagnostics of Cataclysmic Variables and Galactic Ridge X-ray Emission
• The size of the accretion region in intermediate polars: eclipses of XY Arietis observed with RXTE
• A precise HST parallax of the cataclysmic variable EX Hydrae, its system parameters, and accretion rate
• High-resolution spectroscopy of the intermediate polar EX Hydrae. I. Kinematic study and Roche tomography
• Roche tomography of cataclysmic variables - IV. Starspots and slingshot prominences on BV Cen
• Origin of the Galactic Diffuse X-ray Emission: Iron K-shell Line Diagnostics
• Hubble Space Telescope STIS Spectroscopy of Long Period Dwarf Novae in Quiescence
• Infrared Spectroscopic Observations of the Secondary Stars of Short Period Sub-Gap Cataclysmic Variables
• A Systematic X-ray Study of the Dwarf Novae Observed with Suzaku
• Measuring the masses of Intermediate Polars with NuSTAR: V709 Cas, NY Lup and V1223 Sgr
• High spectral resolution time-resolved optical spectroscopy of V893 Sco
• An Empirical Correlation of $T_{\max }$ - $M_{\mathrm{WD}}$ of Dwarf Novae and The Average White Dwarf Mass in Cataclysmic Variables in the Galactic Bulge

Cited by in corpus (8)

• Measuring the masses of magnetic white dwarfs: A NuSTAR Legacy Survey
• Massive White Dwarfs in the Galactic Center: A Chandra X-ray Spectroscopy of Cataclysmic Variables
• Classifying IGR J18007-4146 as an intermediate polar using XMM and NuSTAR
• On the nature of the anomalous event in 2021 in the dwarf nova SS Cygni and its multi-wavelength transition
• Classifying IGR J15038-6021 as a magnetic CV with a massive white dwarf
• V1082-Sgr: A magnetic cataclysmic variable with a lobe-filling companion star
• Dynamical mass of the white dwarf in XY Ari: a test for intermediate polar X-ray spectral models
• The very faint X-ray transient Swift J174610-290018 at the Galactic center