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| Main Authors: | , , , |
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| Format: | Preprint |
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2026
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| Subjects: | |
| Online Access: | https://arxiv.org/abs/2602.22337 |
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| _version_ | 1866914351967895552 |
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| author | Islam, Nazma Mukai, Koji Leutenegger, Maurice A. Pratt, Gabriel W. |
| author_facet | Islam, Nazma Mukai, Koji Leutenegger, Maurice A. Pratt, Gabriel W. |
| contents | Non-magnetic Cataclysmic Variables (CVs) show two distinct X-ray components: a hard, optically thin component and a soft, optically thick, blackbody-like component, both produced in the boundary layer between the accretion disk and the White Dwarf (WD). An additional soft component originating from a more extended region has been reported in few CVs. In a short Chandra exposure, we identified a tentative X-ray eclipse in UU Aqr, a non-magnetic CV which shows deep optical eclipses. Using observations with the Nuclear Spectroscopic Telescope Array (NuSTAR) and the XMM-Newton, we detect total eclipses in the orbital intensity profiles of this system in the hard X-ray band (3-10 keV with XMM and 3-25 keV with NuSTAR). However, the soft X-ray band (0.3-2.0 keV) shows no evidence of an eclipse. Detailed eclipse modeling, energy-resolved power spectral analysis and broadband spectral modeling indicate that the hard absorbed X-ray emission originates from a compact region near the WD, such as a boundary layer, while the soft, unabsorbed and un-eclipsed X-ray emission originates in an extended region. Neither scattering of hard X-rays nor colliding winds can account for the observed un-eclipsed soft emission. We instead propose that this component is produced by shocks within vertically extended, radiatively driven accretion-disk winds. We also provide new estimates on the emitting regions, mass and radius of the WD and the donor star using eclipse modeling. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2602_22337 |
| institution | arXiv |
| publishDate | 2026 |
| record_format | arxiv |
| spellingShingle | Unveiling the X-ray properties of the eclipsing Cataclysmic Variable UU Aqr: spatially and spectrally-resolved two-component emission Islam, Nazma Mukai, Koji Leutenegger, Maurice A. Pratt, Gabriel W. High Energy Astrophysical Phenomena Non-magnetic Cataclysmic Variables (CVs) show two distinct X-ray components: a hard, optically thin component and a soft, optically thick, blackbody-like component, both produced in the boundary layer between the accretion disk and the White Dwarf (WD). An additional soft component originating from a more extended region has been reported in few CVs. In a short Chandra exposure, we identified a tentative X-ray eclipse in UU Aqr, a non-magnetic CV which shows deep optical eclipses. Using observations with the Nuclear Spectroscopic Telescope Array (NuSTAR) and the XMM-Newton, we detect total eclipses in the orbital intensity profiles of this system in the hard X-ray band (3-10 keV with XMM and 3-25 keV with NuSTAR). However, the soft X-ray band (0.3-2.0 keV) shows no evidence of an eclipse. Detailed eclipse modeling, energy-resolved power spectral analysis and broadband spectral modeling indicate that the hard absorbed X-ray emission originates from a compact region near the WD, such as a boundary layer, while the soft, unabsorbed and un-eclipsed X-ray emission originates in an extended region. Neither scattering of hard X-rays nor colliding winds can account for the observed un-eclipsed soft emission. We instead propose that this component is produced by shocks within vertically extended, radiatively driven accretion-disk winds. We also provide new estimates on the emitting regions, mass and radius of the WD and the donor star using eclipse modeling. |
| title | Unveiling the X-ray properties of the eclipsing Cataclysmic Variable UU Aqr: spatially and spectrally-resolved two-component emission |
| topic | High Energy Astrophysical Phenomena |
| url | https://arxiv.org/abs/2602.22337 |