Search

In this paper we test if the ∼0.3–15 keV XMM-Newton EPIC pn spectral continuum of IPs can be described by the thermal Comptonization compTT model. We used publicly observations of 12 IPs (AE Aqr, EX Hya, V1025 Cen, V2731 Oph, RX J2133.7+5107, PQ Gem, NY Lup, V2400 Oph, IGR J00234+6141, IGR J17195-4100, V1223 Sgr, and XY Ari). We find that our modeling is capable of fitting well the average spectral continuum of these sources. In this framework, UV/soft X-ray seed photons (with 〈kTs〉 of 0.096 ± 0.013 keV) coming presumably from the star surface are scattered off by electrons present in an optically thick plasma (with 〈kTe〉 of 3.05 ± 0.16 keV and optical depth 〈τ〉 of 9.5 ± 0.6 for plane geometry) located nearby (on top) to the more central seed photon emission regions. A soft blackbody (bbody) component is observed in 5 out of the 13 observations analyzed, with a mean temperature 〈kTbb〉 of 0.095 ± 0.004 keV. We observed that the spectra of IPs show in general two photon indices Γ, which are driven by the source luminosity and optical depth. Low luminosity IPs show 〈Γ〉 of 1.83 ± 0.19, whereas high luminosity IPs show lower 〈Γ〉 of 1.34 ± 0.02. Moreover, the good spectral fits of PQ Gem and V2400 Oph indicate that the polar subclass of CVs may be successfully described by the thermal Comptonization as well. [ABSTRACT FROM AUTHOR]

In magnetic cataclysmic variables (mCVs), X-ray radiation originates from a shock-heated, multi-temperature plasma in the post-shock region near the white dwarf’s surface. These X-rays are modified by a complex distribution of absorbers in the pre-shock region. The presence of photoionized lines and warm absorber features in the soft X-ray spectra of these mCVs suggests that these absorbers are ionized. We developed the ionized complex absorber model zxipab, which is represented by a power-law distribution of ionized absorbers in the pre-shock flow. Using the ionized absorber model zxipab along with a cooling flow model with a reflection component, we model the broadband Chandra/High-Energy Transmission Grating (HETG) and Nuclear Spectroscopic Telescope Array (NuSTAR) spectra of two intermediate polars (IPs): NY Lup and V1223 Sgr. We find that this model describes well many of the H- and He-like emission lines from medium-Z elements, which arise from a collisionally excited plasma. However the model fails to account for some of the He-like triplets from the medium-Z elements, which points toward their photoionized origin. We do not find compelling evidence for a blackbody component to model the soft excess seen in the residuals of the Chandra/HETG spectra, which could be due to uncertainties in the estimation of the interstellar absorption of these sources using the Chandra/HETG data and/or excess fluxes seen in some photoionized emission lines which are not accounted for by the cooling flow model. We describe the implications of this model with respect to the geometry of the pre-shock region for these two IPs. [ABSTRACT FROM AUTHOR]