The Scattering of X‐Rays by Interstellar Dust on the Microarcsecond Scale
| Autor: | David Lee Windt, Webster Cash, Steven M. Kahn |
|---|---|
| Rok vydání: | 2000 |
| Předmět: |
Physics
Point source Astrophysics::High Energy Astrophysical Phenomena Extinction (astronomy) Astronomy Flux Astronomy and Astrophysics Astrophysics::Cosmology and Extragalactic Astrophysics Astrophysics Dust lane Galaxy Space and Planetary Science Halo Surface brightness Astrophysics::Galaxy Astrophysics Cosmic dust |
| Zdroj: | The Astrophysical Journal. 528:306-309 |
| ISSN: | 1538-4357 0004-637X |
| DOI: | 10.1086/308145 |
| Popis: | We have calculated on a small angular scale the distribution of X-rays (e.g., as originating from a point source) scattered by interstellar dust. In addition to the well-known, large-diameter (i.e., hundreds of arcseconds) X-ray halo due to dust distributed along the line of sight to the source, we show that material clumped very close to the source gives rise to a bright, small-diameter (subarcsecond) X-ray halo. The diameter of this inner "microhalo" decreases, and the relative surface brightness increases, as the relative concentration of dust very near the source increases. For example, we expect that the 1 keV X-ray microhalo surrounding a point source in M87 would have a diameter of order 1 microarcsecond (μas) and a surface brightness relative to the point source flux of order 10-29 μas-2 cm2 (H atom)-1, while the large-diameter halo due to scattering from dust within our own Galaxy would have a diameter of order 100'' and a relative surface brightness more than 12 orders of magnitude lower than the microhalo surface brightness. We discuss the consequences of our results with regard to future high-resolution X-ray imaging observations, and also with regard to the possibility of using detailed measurements of the X-ray halo profile to determine the spatial distribution of dust along the line of sight and close to the source. |
| Databáze: | OpenAIRE |
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