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The impact of X-rays on the carbon cycle in the interstellar medium

Supervisors: Dr. Thomas G. Bisbas & Prof. Dr. Stefanie Walch-Gassner

X-rays, along with cosmic-rays, play a central role in understanding the heating mechanisms deep in molecular clouds. X-ray is a key radiation in special environments such as the Center of our Galaxy, active galactic nuclei, supernovae, X-ray binaries and other such systems. They are also important in the environments of smaller objects, such as protoplanetary disks. Modelling the interstellar chemistry with X-rays is thus of great importance, which can help astronomers understand better how the observed spectrum of the aforementioned systems emerges.

So far, the community is generally adopting an X-ray treatment in which its energy is approximated as an one-number value. Although this approach allows us to estimate the importance of X-rays in building the observed spectrum, it does not allow us to understand deeper how the chemical network is affected and how particular reactions are triggered or ceased along the depth of column. To do this, we need to take into account the energy spectrum of X-rays and thus examine how this radiation is attenuated along the line-of-sight.

We have a state-of-the-art astrochemical code which includes already routines treating the energy of X-rays as an one-number value. The task is to expand this approach by inserting user-defined X-ray energy spectrum and perform calculations. The end product will be used to better understand the carbon cycle process in the interstellar medium as well as to better understand observations we have in hand from the Chandra X-ray telescope. This is a programming-intensive thesis project and programming skills are required, with preference to Fortran and/or Python languages.