Phd Projects at CAS
PhD Project in Theory
Galactic cosmic rays (CRs) are a ubiquitous source of ionisation and heating of the interstellar gas. In dense astrophysical environments, such as molecular clouds and dark pre-stellar cores (where UV and x-ray photons are extinguished), the ionization and heating are completely dominated by CRs. One of the principal aims of the CAS-Theory group is to understand the physics of low-energy CRs in molecular gas, by combining advanced theoretical methods of the kinetic theory and plasma physics and applying available observational constraints. These efforts will enable self-consistent modeling of key processes governed by CRs. This includes the dynamical and structural evolution of dense cores and formation of disks, coagulation of dust grains and growth of icy mantles on their surface, ice processing and chemical reactions driven in the mantles as well as in the gas phase, etc.
The penetration of Galactic CRs into molecular clouds and their further transport in dense gas is a complex physical phenomenon. Depending on a number of conditions, CRs can either move freely along the local magnetic field lines, or experience significant scattering on small-scale field fluctuations and propagate diffusively. Also, CRs lose energy due to ionizing collisions with gas molecules. In combination with the realized transport regime, this shapes the local energy spectrum of CRs and thus sets the local ionization rate – the chief parameter that controls a variety of physical and chemical processes. Given that different transport regimes result in quite different dependencies of CR ionization rate on gas column density, the former could be constrained from available and future observations.
We offer a Ph.D. position in the theory of CR propagation in molecular clouds, broadly focused on one of the following topics (or their combination): (i) Physical mechanisms determining the regime of CR transport in molecular clouds, and (ii) CR-induced processes imprinted in observable emission from molecular clouds. The main subject of (i) is the analysis of plasma phenomena that may lead to efficient scattering of CRs in weakly ionized molecular clouds, and comparison of theoretical results with observations. The aim of (ii) is to identify and analyze microphysical processes of CR interaction with gas, which lead to emission detectable in different spectral ranges (from radio to x-ray) with available and next-generation telescopes. The Ph.D. candidate will work in close collaboration with the members of CAS-Theory group, and obtain necessary support and complementary advice from the observational experts.
Supervisor: Dr. Alexei Ivlev
PhD Project in Laboratory
The detection of ions and radicals of complex organic molecules in the interstellar medium (ISM) will put very stringent constraints on a series of interconnected processes like the development of the molecular complexity in the ISM, and the interplay between gas and dust in the formation of complex organic molecules. This is crucial to unveil the complicated interplay between the chemistry happening in the gas phase and on the surface of dust grains, leading to the molecular complexity that we observe in space, and eventually forming the first bricks for the emergence of life. This PhD project will be focused on the spectroscopy of molecules of astrophysical interest, in particular complex organic molecules as well as their radicals and ions. The PhD candidate will have the opportunity to work with several state-of-the-art experiments such as a sub-millimetre free-unit jet (CASJET, see picture below), a discharge absorption cell (CASAC, see picture below), and a chirp-pulsed spectrometer (CAS Labs). The thesis project will be mainly focus on the acquisition and analysis of spectra that will help the identification of new molecules in the ISM. Furthermore, there will be the possibility to participate to the further development of the experiments, as well as work with astronomical data. Supervisor: Dr. S. Spezzano