Photoionized features in the X-ray spectrum of EX Hydrae

Abstract

We present the first results from a long (496 ks) Chandra High Energy Transmission Grating observation of the intermediate polar EX Hydrae. In addition to the narrow emission lines from the cooling post-shock gas, for the first time we have detected a broad component in some of the X-ray emission lines, namely O VIII 18.97, Mg XII 8.42, Si XIV 6.18, and Fe XVII 16.78. The broad and narrow components have widths of ~ 1600 km s^-1 and ~ 150 km s^-1, respectively. We propose a scenario where the broad component is formed in the pre-shock accretion flow, photoionized by radiation from the post-shock flow. Because the photoionized region has to be close to the radiation source in order to produce strong photoionized emission lines from ions like O VIII, Fe XVII, Mg XII, and Si XIV, our photoionization model constrains the height of the standing shock above the white dwarf surface. Thus, the X-ray spectrum from EX Hya manifests features of both magnetic and non-magnetic cataclysmic variables.

accepted in The Astrophysical Journal

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Cited by in corpus (9)

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• Testing the cooling flow model in the intermediate polar EX Hydrae
• X-ray spectroscopy in the microcalorimeter era 4: Optical depth effects on the soft X-rays studied with CLOUDY
• Constraining the accretion geometry of the intermediate polar EX Hya using NuSTAR, Swift and Chandra observations
• Breaking the degeneracy in magnetic cataclysmic variable X-ray spectral modeling using X-ray light curves
• Comptonization as an origin of the continuum in Intermediate Polars
• Broad Observational Perspectives Achieved by the Accreting White Dwarf Sciences in the XMM-Newton and Chandra Eras
• Gravitational Redshift Detection from the Magnetic White Dwarf Harbored in RX J1712.6-2414