More than 5,000 exoplanets have been found over the past couple of decades. These exoplanets show a tremendous diversity, ranging from scorching hot Jupiters, common super-Earths, to widely... Show moreMore than 5,000 exoplanets have been found over the past couple of decades. These exoplanets show a tremendous diversity, ranging from scorching hot Jupiters, common super-Earths, to widely separated super-Jupiters on the planet/brown dwarf boundary. We have now moved into the era of exoplanet atmospheric characterisation. Two crucial techniques for characterizing these exoplanets from the ground are high-contrast imaging and high-resolution spectroscopy. In the first part of the thesis, existing facilities are used to characterize the atmospheres of two of the most accessible types of planets: An ultra-hot Jupiter (WASP-76b) and a young supter-Jupiter (beta Pictoris b). The second part of the thesis develops instrumental concepts that are required to push exoplanet characterization towards smaller and closer-in planets. It shows how we can choose between spectral resolution, bandwidth, and field-of-view in developing an instrument for exoplanet detection, and how one can design an nearly optimal wavefront sensor for adaptive optics. Finally, it is demonstrated how machine learning techniques can help us improve the performance of these adaptive optics systems such that we can reach deeper contrasts for exoplanet imaging and characterization. Show less
The first direct detection of gravitational waves opened the possibility of mapping the Universe via this new and independent messenger. Indeed, during their propagation, gravitational waves pick... Show moreThe first direct detection of gravitational waves opened the possibility of mapping the Universe via this new and independent messenger. Indeed, during their propagation, gravitational waves pick up information about the spacetime as they are affected by its expansion and by the matter structures along the propagation path. The aim of this Thesis is to investigate which cosmological information is accessible from a gravitational wave detection, with a specific interest in the late time Universe. Show less
This thesis examines silicon pore optics (SPO), a technology that exploits silicon wafers from the semiconductor industry to create extremely high quality X-ray optics, by studying its... Show moreThis thesis examines silicon pore optics (SPO), a technology that exploits silicon wafers from the semiconductor industry to create extremely high quality X-ray optics, by studying its manufacturing process, applications, and prospects. SPO technology has become very mature thanks to the continuous development efforts to prepare for the industrial production of Athena, the largest space-borne X-ray telescope yet to be launched. In effect, SPO is also a versatile technology that can be further developed for a wide range of applications, including radiation therapy. Show less