From a biased perspective: quasars, mergers, and planet-forming discs

Pizzati, E.

This thesis is a (biased) journey through very different topics in astrophysics: quasars and new populations of active galactic nuclei, gravitational waves from merging black holes, and protoplanetary discs around young stars.
Quasars, powered by accretion onto supermassive black holes, are luminous tracers of early black hole growth. By analyzing their spatial clustering, I show that their distribution reflects the underlying dark matter halo population and constrains black hole accretion in the early Universe. Using new observations from the James Webb Space Telescope, I also investigate compact sources known as “little red dots.” These objects vastly outnumber quasars and exhibit galaxy-like clustering, suggesting a distinct phase of black hole growth or an alternative physical origin.
The thesis then moves into two other frontiers. Future gravitational wave detectors will be sensitive enough to pick up so many black hole and neutron star mergers that their signals may...Show moreThis thesis is a (biased) journey through very different topics in astrophysics: quasars and new populations of active galactic nuclei, gravitational waves from merging black holes, and protoplanetary discs around young stars.
Quasars, powered by accretion onto supermassive black holes, are luminous tracers of early black hole growth. By analyzing their spatial clustering, I show that their distribution reflects the underlying dark matter halo population and constrains black hole accretion in the early Universe. Using new observations from the James Webb Space Telescope, I also investigate compact sources known as “little red dots.” These objects vastly outnumber quasars and exhibit galaxy-like clustering, suggesting a distinct phase of black hole growth or an alternative physical origin.
The thesis then moves into two other frontiers. Future gravitational wave detectors will be sensitive enough to pick up so many black hole and neutron star mergers that their signals may sometimes overlap. I explore how this complicates our ability to measure their properties and suggest ways to disentangle the signals. Finally, I analyze ALMA observations of protoplanetary discs, showing that dust is usually confined to remarkably thin layers, indicative of weak turbulence during planet formation.
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From a biased perspective: quasars, mergers, and planet-forming discs