Non-LTE modeling of supernova-fallback disks

Abstract

We present a first detailed spectrum synthesis calculation of a supernova-fallback disk composed of iron. We assume a geometrically thin disk with a radial structure described by the classical alpha-disk model. The disk is represented by concentric rings radiating as plane-parallel slabs. The vertical structure and emission spectrum of each ring is computed in a fully self-consistent manner by solving the structure equations simultaneously with the radiation transfer equations under non-LTE conditions. We describe the properties of a specific disk model and discuss various effects on the emergent UV/optical spectrum. We find that strong iron-line blanketing causes broad absorption features over the whole spectral range. Limb darkening changes the spectral distribution up to a factor of four depending on the inclination angle. Consequently, such differences also occur between a blackbody spectrum and our model. The overall spectral shape is independent of the exact chemical composition as long as iron is the dominant species. A pure iron composition cannot be distinguished from silicon-burning ash. Non-LTE effects are small and restricted to few spectral features.

arXiv commentApSS, accepted, Proceedings of Isolated Neutron Stars: from the Interior to the Surface, April 24-28, 2006, London, UK

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Cited by in corpus (2)

• The gaseous debris disk of the white dwarf SDSS J1228+1040. HST/COS search for far-ultraviolet signatures
• The Vela Pulsar With an Active Fallback Disk