This week's PhD colloquia are highlighted.
| Date | Time | Title/Abstract | Speaker | Affil. |
|---|---|---|---|---|
| 04/09 Thursday DM 1.09 | The Sky is Made of Lava - How lava worlds reveal their interiors through their atmospheres Hot rocky exoplanets are a class of planets that have seen a surge of interest in the last decade. Due to their proximity to their host stars, they have surface temperatures exceeding 1500 K—enough to melt their crusts and create vast lava oceans that can cover a significant portion, if not all, of their surface. Such lava oceans provide an interface between a planet's interior and atmosphere, allowing the atmospheric chemical composition to be directly influenced by the interior - providing a unique view into rocky planet interiors. This thesis focuses on developing lava vaporisation models and implementing them within larger code frameworks used to produce atmospheric spectra of these planets. | Christiaan van Buchem | ||
| 08/09 Monday BW0.32 | 15:00 | Patterned detectors: From design to science Patterned detectors are an existing technology that can be found in almost all color cameras. These patterned detectors consist of adding optical filters in a pattern on a pixel level on top of a detector. In common cameras the filters are broadband red, green and blue color filters. However, in this talk (and thesis) I focus on more varied spectral filters and polarimetric filters. I will first show a design framework for a patterned detector for hyperspectral imaging. This framework makes use of automatic differentiation to train on existing hyperspectral datasets to determine the best spectral filters and the best layout of those spectral filters on the detector. I extend this framework by adding polarimetric filters as well, enabling the design of a spectro-polarimeter. Halfway the colloquium, I shift focus from the theoretical design to an already existing commercial patterned detector for color and gray-scale polarimetric imaging. I will describe a calibration campaign that we conducted for these patterned detector cameras and the accuracies that we can expect from them. Finally, we used one of the now calibrated patterned detectors and integrated it into a new instrument that measures the linear polarization properties of the northern lights. | Thijs Stockmans | |
| 20/10 Monday DM1.15 | Destroy, Create, Transform and Sublimate. Laboratory Dissociation Studies on Polycyclic Aromatic Hydrocarbons and Analogues Polycyclic aromatic hydrocarbons (PAHs) and their nitrogen analogues (PANHs) are widely considered as carriers of the aromatic infrared bands (AIBs), which are observed throughout the interstellar medium (ISM). Yet, there are still many uncertainties regarding the dissociation behavior and astrochemical role of PA(N)Hs in the ISM. In this colloquium, I will present the work done during my PhD to elucidate these topics. Using dissociative photoionization I was able to determine seven fragmentation pathways of benzonitrile, and formation routes potentially relevant for space. Mid-infrared (mid-IR) spectra of 1,5,9-triazacoronene (TAC), a triply nitrogenated coronene molecule, and its protonated counterpart show close correspondence with observed AIB features. Photodissociation experiments on TAC show the potential formation of nitrogen-bearing fragments linked to interstellar cyanopolyynes. Additional experiments on the dissociation fragments of PA(N)Hs show that they readily react with water, revealing a new potential bottom-up formation pathway towards complex organic molecules (COMs) in the ISM. Finally, the IR spectrum of doubly dehydrogenated (i.e. molecular hydrogen loss) naphthalene is investigated and showed significant isomerization, leading to the formation of five-membered carbon rings. These results highlight how (polycyclic) aromatic species can act as key drivers of molecular complexity in the ISM and further broaden our understanding of their chemical role. | Jerry Kamer | ||
| 28/10 BE0.18 | From a Biased Perspective: Quasars, Mergers, and Planet-Forming Discs My PhD has been a (biased) journey across diverse topics: from quasars and emerging AGN populations to gravitational-wave signals and protoplanetary discs. In this colloquium, I will focus on the core theme of my thesis: the growth of supermassive black holes as traced by quasar activity across cosmic time. I will show how the spatial clustering and luminosity function of quasars, taken together, constrain the dark-matter halos that host quasars and the duty cycle of accretion. These diagnostics are especially powerful at high redshift, where the appearance of billion-solar-mass black holes within a few hundred million years of the Big Bang remains a central puzzle. I will also highlight the impact of JWST in mapping early quasar environments and revealing new AGN candidates—most notably the "little red dots"—that challenge our understanding of black hole evolution. I'll conclude with the key open questions arising from this work and a roadmap for addressing them. | Elia Pizzati | ||
| 11/11 BW0.31 | 15:15 | TBA | Silvia Onorato | |
| 12/11 Wednesday DM1.15 | 13:00 | TBA | Elina Kleisioti |
For questions and/or suggestions concerning the colloquium series. Please contact Andrew Sellek (e-mail ).