Vorträge, Seminare, Ereignisse

Abstract
The lives of galaxies are governed by the accretion of gas, its consumption via star formation, its removal or heating through feedback, and environmental effects. In recent years, the James Webb Space Telescope (JWST) has unveiled an unexpectedly high density of massive quiescent galaxies at high redshift , challenging standard models of early galaxy growth. Cosmological simulations predict that these quenched systems preferentially live in dense regions, where they experience accelerated growth and more feedback from Active Galactic Nuclei (AGN). Observationally, clustered environments indeed exhibit enhanced AGN activity, and AGN feedback is increasingly viewed as the primary driver of quenching in massive galaxies. In this talk, I will present JWST/NIRISS slitless spectroscopic observations of a merging protocluster at z=3 that simultaneously hosts two quiescent galaxies and a luminous, starbursting quasar at its centre. I will discuss the kinematics, substructure, and halo properties of the system, as well as examine its evolutionary stage and AGN incidence. The central quasar is an example of the rare and intense “extremely red quasar” phase: a luminous and dusty population thought to constitute an early break-out stage, with ionised outflows reaching thousands of km/s - the most extreme warm winds known to date. Spatially resolved observations with JWST/NIRSpec offer a detailed view on gas dynamics, mass loading, and localised physical conditions, bridging the extended environment down to the nucleus. At low redshifts, I will focus instead on a population of AGN with low-velocity ionised outflows and suppressed star formation, which may represent a later phase of feedback. New spatially resolved molecular gas measurements with NOEMA enable a detailed kinematic comparison of cold and warm gas phases, and reveal how the outflows reshape the cold gas reservoir while regulating star formation efficiency. Together, these results showcase distinct examples of how AGN feedback can manifest across different cosmic times and environments.

Abstract
KoCo Signature Speaker (GC)

Abstract

In the Lambda Cold Dark Matter (ΛCDM) framework, galaxies emerge at the centre of dark matter (DM) halos forming stars in a way connected to the growth of such halos. On the micro scale, supermassive black holes (SMBH) accrete gas and grow in close connection with the properties of their host galaxies (see e.g. the BH–galaxy/group scaling relations). Energetic processes within galaxies may impact their surroundings, at galactic and/or halo scales, influencing future gas accretion and star formation (SF). Feedback from radio-loud Active Galactic Nuclei (AGN), in particular, is often invoked to explain the observed properties of massive galaxies in the local Universe. The role of jet-induced feedback at higher redshifts (z ≳ 1) is less clear, as radio-AGN activity shifts towards lower-mass, mostly star-forming galaxies (SFG). Shedding light on the interplay between SMBHs, galaxies and DM halos requires observations over large cosmological volumes to probe all environments and include the rarest galaxy/AGN populations, while also being gas/dust insensitive to unveil the dominant contribution of obscured AGN and SF activity. Next generation radio–continuum (RC) surveys will provide a unique tool to reach a complete and unbiased census of both AGN and SFG populations at the peak epoch of cosmic assembly (z~1-3) and beyond.

The SKA Observatory (SKAO) is expected to revolutionise our knowledge in all fields of modern astrophysics and cosmology and will have substantial scientific applications also in the field of general and astroparticle physics. In the lead-up to the SKAO, radio astronomy is rapidly advancing under the impulse of several new, state-of-the-art facilities, collectively known as SKA Precursors and Pathfinders. The advent of MeerKAT and LOFAR, in particular,  is rapidly improving and transforming our understanding of the extra-galactic radio sky. Ongoing deep RC surveys, in combination with extensive multi-wavelength coverage, are providing an unprecedented view on the physical properties of the faint radio populations, allowing us to trace SFGs and AGN across cosmic time, in a dust/gas-unbiased manner. Deep observations of well-known extra-galactic fields, in particular, represent natural test-beds for the science that will be delivered by the SKAO, in synergy with upcoming facilities working at other wavebands. 

In this talk I will first provide a brief overview of the SKAO and its main science drivers, which span diverse areas such as the formation of Earth-like planets, the origin of gravitational waves and other transient phenomena, the origin of cosmic magnetic fields, the formation and growth of stars, galaxies and black holes, as well as large scale structures, back to the epoch of reionization and cosmic dawn.  I will then focus on galaxy/AGN co-evolution and I will discuss some of the recent results coming from LOFAR and MeerKAT deep fields. I will conclude with an overview of future plans and perspectives.

KoCo Signature Speaker (GC)

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Gaia, developed and operated by the European Space Agency, was launched in 2013, and operated until January 2025. It's creating a revolutionary six-dimensional map of our Galaxy by measuring the accurate distances and space motions of some three billion stars. While the measurement of star positions has a very long history, stretching back more than 2000 years, Gaia's accuracies exploit the numerous advantages of measurements made from above the Earth's atmosphere. Absolute positional accuracies of order 10 micro-arcsec can register stellar motions that would require more than 10,000 years to be discerned on the ground.  This is providing a major advance in understanding stellar evolution, and in unravelling the composition, structure, and history of our Galaxy's formation. I will not focus on the technical details, but provide a "big picture" of Gaia's scientific advances.

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