"Dark Matter" in Accretion Disks

Abstract

Using Spitzer Space Telescope photometric observations of the eclipsing, interacting binary WZ Sge, we have discovered that the accretion disk is far more complex than previously believed. Our 4.5 and 8 micron time series observations reveal that the well known gaseous accretion disk is surrounded by an asymmetric disk of dusty material with a radius approximately 15 times larger than the gaseous disk. This dust ring contains only a small amount of mass and is completely invisible at optical and near-IR wavelengths, hence consisting of "dark matter". We have produced a model dust ring using 1 micron spherical particles with a density of 3 g/cm${}^3$ and with a temperature profile ranging from 700-1500K. Our discovery about the accretion disk structure and the presence of a larger, outer dust ring have great relevance for accretion disks in general, including those in other interacting binary systems, pre-main sequence stars, and active galaxies.

34 pages, 8 figures (3 in color). Accepted to ApJ

References in corpus (7)

• Spitzer/IRAC Photometry of M, L, and T Dwarfs
• Radio, X-ray, and gamma-ray Emission Models of the Colliding Winds Binary WR 140
• The prototype colliding-wind pinwheel WR 104
• Dynamical constraints on the component masses of the cataclysmic variable WZ Sge
• HST/STIS Spectroscopy and Modeling of the Long Term Cooling of WZ Sagittae following the July 2001 Outburst
• First Spitzer Space Telescope Observations of Magnetic Cataclysmic Variables: Evidence for Excess Emission at 3--8 microns
• The Mid-Infrared Spectrum of the Short Orbital Period Polar EF Eridani from the Spitzer Space Telescope