Dr Roshi is currently engaged in two research projects. The first one is an observational study of fully and partially ionized gasses in the Galactic Interstellar Medium (ISM) and the second one is an experimental astronomy project to detect faint spectral lines from astronomical sources by suppressing man made radiofrequency interference.

Fully and partially ionized gasses in the Galactic interstellar medium The Milky Way is composed of numerous clusters of stars scattered throughout the spiral arms of the galaxy. In between stars there is a tenuous, gaseous matter which is referred to as the interstellar medium. Studying the interstellar medium can give us many critical clues on the evolution of our Galaxy and the types of stars and planets that are formed.

From previous studies and astronomical observations it is known that the interstellar medium is in a constant state of flux. The most abundantly found element in the interstellar medium is Hydrogen. Apart from Hydrogen there are also small amounts of Helium, Carbon and other elements in the ISM. Interestingly, Hydrogen in the interstellar medium is in different forms in different parts of the ISM. While in some areas it is in atomic form, in others it is in molecular form and in still other areas, it is ionized. It is this diffuse ionized gas that is the focus of a currently ongoing large-scale recombination line survey with the Green Bank Telescope.

Recombination lines of hydrogen and helium are used to understand the origin of the diffuse ionized gas. It is also known that in the ISM there is ionized carbon in regions surrounding the clouds of molecular hydrogen. It is the intent of this survey to also search for recombination lines of carbon from which valuable information can be gleaned regarding the formation of molecular clouds.

Detection of weak astronomy signals in the presence of man-made radio frequency interference. For radio astronomers, man made radio transmissions present an enormous challenge as these signals are much stronger than the very faint ‘radio’ signals from celestial objects. There are some frequency bands that are protected for radio astronomy research purposes, but astronomers would of course love to observe at frequency ranges outside these allocated bands. This is especially true in frequency bands where interesting spectral lines from astronomical sources are present. In order to achieve this goal, new, advanced ‘noise canceling’ technologies need to be developed.

Initial project focus will be in two frequency ranges 30-40 MHz and 1.4 to 3.4 GHz. Carbon recombination lines from interstellar medium can be detected in the 30-40 MHz range, while spectral lines of OH and CH molecules from the so-called CO dark molecular clouds are expected to be detected in the 1.4 to 3.4 GHz frequency range.

Students working on this project will have the opportunity to build cutting-edge systems using field programmable gate arrays, 100Gb Ethernet and sensitive analog devices. On completion of instrument building, students will be involved in installing the system at field stations, collecting data and implementing signal processing algorithms to detect spectral lines with radio telescopes.