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The standard disk is often inadequate to model disk-dominated cataclysmicvariables (CVs) and generates a spectrum that is bluer than the observed UVspectra [Puebla et al 2007]. X-ray observations of these systems reveal anoptically thin boundary layer (BL) expected to appear as an inner hole in thedisk. Consequently, we truncate the inner disk. However, instead of removingthe inner disk, we impose the no-shear boundary condition at the truncationradius, thereby lowering the disk temperature and generating a spectrum thatbetter fits the UV data. With our modified disk, we analyze the archival UVspectra of three novalikes that cannot be fitted with standard disks. For theVY Scl systems MV Lyr and BZ Cam, we fit a hot inflated white dwarf WD with acold modified disk ($\dot{M} \sim $ a few $10^{-9}M_{\odot}$/yr). For V592 Cas,the slightly modified disk ($\dot{M} \sim 6 \times 10^{-9}M_{\odot}$/yr)completely dominates the UV. These results are consistent with Swift X-rayobservations of these systems [Balman et al 2014], revealing BLs merged withADAF-like flows and/or hot coronae, where the advection of energy is likelylaunching an outflow and heating the WD, thereby explaining the high WDtemperature in VY Scl systems. This is further supported by the fact that theX-ray hardness ratio increases with the shallowness of the UV slope in a smallCV sample we examine. Furthermore, for 105 disk-dominated systems, theInternational Ultraviolet Explorer (IUE) spectra UV slope decreases in the sameorder as the ratio of the X-ray flux to optical/UV flux: from SU UMa's, to UGem's, Z Cam's, UX UMa's, and VY Scl's.

astrophysical journal/the astrophysical journal

Modifying the Standard Disk Model for the Ultraviolet Spectral Analysis  of Disk-dominated Cataclysmic Variables. I. The Novalikes MV Lyrae, BZ  Camelopardalis, and V592 Cassiopeiae