An Active Galactic Nucleus (AGN) is a highly luminous region at the center of a galaxy, powered by the accretion into a supermassive black hole and emitting energy from radio waves to gamma rays,... Show moreAn Active Galactic Nucleus (AGN) is a highly luminous region at the center of a galaxy, powered by the accretion into a supermassive black hole and emitting energy from radio waves to gamma rays, often outshining the host galaxy. In the context of the AGN unification paradigm, the concept of the dusty “torus” plays a crucial role to discern between Type-1 and Type-2 AGNs depending on whether it obscures the AGN from the observer’s line of sight. NGC 1068, a well-studied AGN across the electromagnetic spectrum, is a nearby barred galaxy (d=14.4 Mpc) considered the prototypical Type-2. Using MATISSE at the VLTI, we have obtained direct evidence of the dusty torus enshrouding the AGN in NGC 1068. The multi-band capabilities of the instrument in the infrared wavelengths and the high spatial resolution that the interferometric technique can achieve have enabled us to study in detail the characteristics of the obscuring dust and its spatial distribution. We further analyse ALMA observations of the molecular gas with a comparable angular resolution. The revealed kinematics suggest an ongoing merger event, potentially contributing to the observed asymmetries in the torus and the water-maser disk, offering new insights into the dynamic processes in AGNs. Show less
From its origin at the center of a star to the edge, through the surrounding gas and dust in the distant galaxy, through the intergalactic medium, traveling billions of light years only to be... Show moreFrom its origin at the center of a star to the edge, through the surrounding gas and dust in the distant galaxy, through the intergalactic medium, traveling billions of light years only to be reflected by a mirror and captured by a detector; the little amount of light observed from galaxies in the early universe contains a wealth of historic information. This thesis concentrates on translating the luminosities and colors of distant galaxies to physical properties such as distance, mass, age of the stellar population, and dust content. Analyzing deep optical and infrared observations of distant (redshift z~2.5) galaxies, we learn that massive galaxies have on average redder colors than less massive galaxies, although simulations show that mass underestimates of star-forming galaxies are possible. Roughly half of the red galaxies at high redshift owe their color to an old, quiescent stellar population. The other half is still actively star-forming, but obscured by large columns of dust. The abundance of star-forming and quiescent galaxies is consistent with a model that assigns a key role to collisions between gas-rich disk galaxies involving quasar activity, and leaving red spheroids as remnants. However, this model does not reproduce the colors of dusty red galaxies. Show less
