This week's PhD colloquia are highlighted.
|07/09||Interstellar Catalysts and the PAH Universe|
rganic molecules in interstellar space are important as they influence the structure of galaxies and star formations. Studying catalytic processes in space allows us to understand how molecular species are formed and chemically evolved in the interstellar medium and solar system objects. Quantum chemical methods, such as Density Functional Theory (DFT), can be employed to study the chemical pathways for the formation of molecular species, which is challenging with only observations and experiments. This thesis studies, with DFT methods, how polycyclic aromatic hydrocarbons (PAHs), the most abundant organic species in space, catalyze the formation of molecular hydrogen in the interstellar medium. Specifically, how linear PAHs become superhydrogenated and how the presence of Stone Wales defect in PAHs contributes to their catalytic activity for molecular hydrogen formation. In addition, this thesis reports the study of the catalytic activity of forsterite, a silicate mineral abundant in grains, asteroids, and meteorites. Specifically, the presence of Schottky MgO vacancy in forsterite can catalyze the C-H activation of PAHs as the first step to study the breakdown reaction of PAHs in asteroidal settings. The latter is indispensable to understand the formation of the so-called organic inventory of solar system objects.
|Dario Campisi||Leiden Observatory|
|14/09||11:00||High-contrast imaging polarimetry of exoplanets and circumstellar disks|
Abstract to follow.
|Rob van Holstein||Leiden Observatory|
|21/09||11:00||Galaxy Alignments from Multiple Angles|
Weak Gravitational Lensing is a powerful probe to investigate the dark sector of our Universe. It uses the distortion of galaxy shapes of background galaxies caused by the lensing effect of the matter distribution along the line of sight to infer the amount and the distribution of matter in the Universe. An important complication arises because galaxy shapes are not randomly oriented in the sky before being lensed. Instead, galaxies form and live inside dark matter haloes: they are exposed to the tidal fields generated by the surrounding matter distribution, which leads to a coherent alignment on physically close galaxies, called intrinsic alignment. In this colloquium, I will present our investigation of the dependence of intrinsic alignment on galaxy properties using different techniques, and how this should be accounted for when modelling intrinsic alignment in weak lensing studies.
|Maria Cristina Fortuna||Leiden Observatory|
For questions and/or suggestions concerning the colloquium series, please contact Simon Portegies Zwart (e-mail )