X-ray Studies of Interstellar and Intergalactic Dust
(click here for PDF)
Dust grain composition, sizes, and spatial distribution can be directly measured with high resolution X-ray imaging and spectroscopy. Dust in the foreground of bright point sources will scatter X-rays through small angles, producing a diffuse `halo' image. The scattering cross-section is most sensitive to large dust grains, which are typically missed in UV, optical, and infrared studies. The dust-to-gas mass ratio and elemental constituents of dust grains can also be determined from X-ray spectroscopy. I demonstrate how a Bayesian analysis of the scattering halo around Cyg X-3 yields a grain size distribution and mass ratio that does not match properties typically assumed of Galactic dust. Finally, I will discuss the prospects for using quasars to measure the cosmic density of dust grains in intergalactic space.
An archive of select poster and presentation slides.
Light echo from star V838
(NASA/ESA/H E Bond)