This thesis presents pioneering work on the panchromatic emission of some of the most luminous galaxies in the early Universe: star forming galaxies and active galactic nuclei. Using state-of... Show moreThis thesis presents pioneering work on the panchromatic emission of some of the most luminous galaxies in the early Universe: star forming galaxies and active galactic nuclei. Using state-of-the-art statistical methods and new-generation radio-to-X-rays instruments, this thesis expands the parameter space covered by current multi-wavelength studies of galaxy evolution. In particular, this thesis pushes three different frontiers. The statistical frontier is explored by developing a sophisticated statistical tool to robustly recover the parameters required to model multi-wavelength emission. The wavelength frontier is pushed forward by exploring galaxy evolution from the new spectral window at low-frequency radio, opened by the LOFAR instrument. Finally, the resolution frontier will be pushed by exploring the distribution of emission components across the spectrum using a combination of high-resolution ALMA and HST imaging. Show less
One of the major unresolved questions in astronomy is: how do galaxies form and evolve? In the local universe we can distinguish between actively star-forming and quiescent galaxies. Quiescent... Show moreOne of the major unresolved questions in astronomy is: how do galaxies form and evolve? In the local universe we can distinguish between actively star-forming and quiescent galaxies. Quiescent galaxies are typically the most massive, with elliptical morphologies and red optical colors. The mechanisms that cause star-formation in galaxies to be turned off, so that star-forming galaxies become quiescent, are not yet well understood. Using the FourStar Galaxy Evolution Survey (ZFOURGE), comprising near-infrared data of over seventy thousand galaxies, we aim to find and study the first quiescent galaxies. First we describe the data products of ZFOURGE. Then we present the discovery of 15 very massive quiescent galaxies over 12 billion years ago, when the universe was only 1.6 billion years old. The implication is that they must have formed extremely rapidly, with explosively high star-formation rates. They are very compact, and much smaller than nearby quiescent galaxies as well as equally distant star-forming galaxies. Considering number counts and average properties of star-forming galaxies at even earlier times, we speculate that their formation history may have included a dust-obscured star-burst, possibly also forming a dense stellar core. Finally, we present a study of star-forming galaxy kinematics 11 billion years ago. Show less
Ten billion years ago the Universe was at the peak of its star formation activity, which has been declining since then. This thesis investigates, with novel spectroscopic data from Hubble Space... Show moreTen billion years ago the Universe was at the peak of its star formation activity, which has been declining since then. This thesis investigates, with novel spectroscopic data from Hubble Space Telescope, the evolution of the galaxy population from that particular period, the so-called "Cosmic Noon", to the present epoch. The main topics addressed are the contribution of emission lines to the optical light of galaxies through cosmic time, the star formation rates of actively star-forming galaxies and quenched galaxies, and the evolution of the stellar ages of galaxies from 10 billion years ago to the current time. Show less
Galaxies have changed drastically over the past 10 billion years. This thesis deals with these changes, focusing on evolution in the structure of very massive galaxies with a range of stellar... Show moreGalaxies have changed drastically over the past 10 billion years. This thesis deals with these changes, focusing on evolution in the structure of very massive galaxies with a range of stellar population properties. The main subjects addressed are the rapid changes in the sizes of old galaxies, the gradients in stellar population content within galaxies, and the predictions from theoretical models regarding these properties. Show less
