Radiative Transfer

Resembling a rippling pool illuminated by underwater lights, the Egg Nebula offers astronomers a special look at the normally invisible dust shells swaddling an aging star. Credit: NASA/STSci/AURA

It often happens that an interesting astrophysical source is embedded in dust (star, galactic nucleus, etc.). In this case, radiation from the source is scattered, absorbed and reemitted by the dust, and the emerging processed spectrum often provides the only available information about the embedded object. This situation is akin to seeing lights from a car through a thick layer of fog, and you need to figure out what kind of car is coming at you. Astronomers can handle this situation with the aid of sophisticated computer modeling. Understanding the physics of all the relevant processes and developing such a tool was the main part of my Ph.D. work (which was so much fun because I had a perfect personality match with my wonderful advisor and friend Moshe Elitzur [the match was dominated by the fact that we are both very stubborn, as testified repeatedly by our better halfs]).

It turned out that the dust radiative transfer problem (i.e. figuring out the car model) is not as hopeless as one would guess, as we detailed in Ivezić & Elitzur (1997). We used these results to design a very fast and general code Dusty, which appears to still be the most used astrophysical dust radiative transfer code.