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.
Interstellar Chemistry with X-rays
X-ray spectroscopy can reveal the presence and abundance of heavy elements in space. Many of these — including magnesium, silicon, iron, and oxygen — are widely suspected to be the main constituents of interstellar dust. I will describe experiments that directly probe the composition of dust grains along the line of sight to luminous X-ray sources.
X-ray Scattering from Intergalactic Dust
I explore the possibility of detecting large grey dust in the intergalactic medium. This poster presentation won a Chambliss Astronomy Achievement Award.
Every day two tons of cosmic dust rain down upon the surface of the Earth. In this session we will explain how you can go hunting for space rocks in your own back yard. We will explore the phenomenon of micrometeorites and their journey from space to your flower bed.
Listen here at the 365 Days Astronomy Podcast website
We will explore the history and legacy of the most publicly known yet misunderstood astronomical object. We’ll be interviewing people on the streets of New York City to highlight common questions and misconceptions about Black Holes.
Listen here at the 365 Days of Astronomy Podcast website
An archive of select poster and presentation slides.
Light echo from star V838
(NASA/ESA/H E Bond)