Structure and Dynamics of Nearby Galaxies

Counter-rotating components in galaxies: Over 15% of the stars in nearby galaxies move in the opposite direction to the rest of the galaxy. We have developed an innovative technique that allows us to spectroscopically separate the kinematics and properties of the counter-rotating stellar populations, enabling us to distinguish between the various proposed formation scenarios.
Contacts: Enrico Maria Corsini, Alessandro Pizzella

Stellar populations in nearby disk galaxies: The systematic study of stellar populations in lenticular and spiral galaxies in the local Universe allows us to characterize their age and formation mechanisms. We are developing new infrared spectral indices to measure the age and metal content of stars in dust-rich galaxies.
Contacts: Enrico Maria Corsini, Alessandro Pizzella

Mass of supermassive black holes in galaxies: We actively participate in the Space Telescope and Optical Reverberation Mapping Project, which uses ground-based and space-based telescopes to determine the mass of the central black hole in active galactic nuclei. Additionally, we have developed an original dynamical analysis technique that allows us to estimate the mass of the central black hole in non-active galaxies from unresolved kinematic measurements of ionized gas.
Contacts: Elena Dalla Bontà, Enrico Maria Corsini, Alessandro Pizzella

Distribution of luminous and dark matter in galaxies: We study the orbital structure, luminous matter content, dark matter concentration, and scaling relations between the photometric, kinematic, and dynamical properties of galaxies to understand the mechanisms and timescales of formation of the stellar body and dark matter halo
Contacts: Enrico Maria Corsini, Alessandro Pizzella .

  Galaxy Evolution

Baryon cycle: The evolution of galaxies across different cosmic epochs is determined by the baryon cycle: gas flowing into galaxies from the cosmic web cools and condenses; new stars form from the molecular gas and feed the central black hole. Feedback processes from the central black hole and stellar winds regulate the inflow of further cold gas from the cosmic web, thus controlling the star formation process. To study this cycle at high redshift, we are involved in various projects that combine JWST data in the near-infrared, which allow us to study the stellar component of galaxies up to high redshift, with ALMA data in the sub-mm, which enable us to quantify the presence of molecular gas and dust, pushing our study to the first galaxies formed after the Big Bang.
Contacts: Paolo Cassata, Giulia Rodighiero

Origin and evolution of the first galaxies: Recent discoveries by the James Webb Space Telescope have opened a new window on the early Universe, revealing an unexpected number of previously unknown galactic populations, which are revolutionizing cosmological models for the formation of the first cosmic sources. Our group is involved in several JWST observational programs aimed at understanding the nature and evolution of these sources, with particular regard to the darkest phases of star formation and the simultaneous accretion activity in supermassive black holes at the centers of galaxies. By combining photometric and spectroscopic data, we aim to reconstruct the contribution of different populations to the star formation history of the Universe in its early stages.
Contacts: Giulia Rodighiero, Paolo Cassata

Statistical properties of galaxy populations: In parallel, we continue to work on systematic studies (luminosity functions, mass functions, counts at various wavelengths from optical to submillimeter) from the cosmic dawn to the "noon" of our Universe, combining data from ground-based observatories (VLT, VISTA, ALMA, etc.) and space-based observatories (EUCLID), and comparing them with models and simulations to interpret their role and evolution. In particular, we have been involved in the development and definition of the ESA EUCLID mission since its inception. We are particularly focused on leveraging the mission's data to build comprehensive and deep samples of galaxies at all cosmic epochs, determining their morphological properties (via high-resolution images from the optical camera) and physical properties (via the near-infrared spectrograph). To better understand the distant Universe, we maintain a research line on the study of the properties of local galaxies, spatially resolved, considered as laboratories to verify the global scaling relations of galaxies (mass, size, SFR) at high redshift.
Contacts: Paolo Cassata, Giulia Rodighiero

Atomic hydrogen in the era of Square Kilometer Array (SKA) precursors: Radio astronomy is currently undergoing a major technological revolution in preparation for the arrival of SKA, a planetary-scale interferometric system, in a few years. Several SKA precursors are currently operational and are already producing scientific data that anticipate future applications. Our group is involved in various collaborations utilizing surveys conducted with the MeerKAT telescope (South Africa), the VLA, and the uGMRT (India). We are particularly interested in studying the statistical properties of atomic hydrogen (HI) in galaxies at cosmological distances that were previously unreachable, to reveal the evolution with redshift of scaling relations between stellar mass, star formation, molecular and atomic gas (with particular reference to the dependence on the environment in which galaxies reside, i.e., the large-scale structure).
Contacts: Giulia Rodighiero, Paolo Cassata

Scaling relations: We work on the formation and evolution of galaxies and galaxy clusters using data from various observational surveys and numerous theoretical models. Our goal is to reconstruct the star formation history in galaxies and understand the role of active black holes at their centers. The main challenge is to understand the "fine-tuning" that links star formation to the structure and dynamics of galaxies. We also study feedback phenomena due to supernovae and active galactic nuclei, as well as the environment in which galaxies reside. We analyze the main scaling relations of galaxies and clusters, aiming to understand their physical origin. Finally, we use high-accretion rate quasars as distance indicators to establish the main parameters of cosmological models (e.g., Ωm and ΩΛ).
Contacts: Mauro D’Onofrio

  Evolution of Active Galactic Nuclei (AGN)

Multi-frequency study of active galactic nuclei: Active Galactic Nuclei (AGN) are among the few cosmic sources capable of emitting photons across all frequencies, from radio waves to gamma rays, and are the brightest non-transient objects in the Universe, visible over vast distances. The origin of this immense luminosity primarily stems from an accretion disk surrounding a supermassive black hole. As gravitational energy converts into luminosity from matter falling towards the black hole, a significant amount of radiation is emitted and observable. Despite their diverse appearances and classifications (Seyfert galaxies, quasars, radio galaxies, blazars), unified models suggest these sources originate from the same type of object, distinguished by the presence or absence of a relativistic plasma jet accelerated by the magnetic field near the black hole. Although much has been learned over the years about these objects and the extreme physical phenomena characterizing them, many aspects remain poorly understood. The origin and dynamics of ionized gas observed at large distances from the black hole in many AGN, for example, still present uncertainties. Similarly, questions persist regarding the evolution of AGN over time, the formation of matter jets near the black hole, the physical phenomena at these high energies, and the interaction between AGN and their host galaxies. Our research group addresses these aspects primarily through optical spectroscopy, as well as observations of AGN at other frequencies such as radio, X-ray, and gamma rays. In addition to acquiring new data with numerous telescopes, including those at Asiago observatories, we analyze large data archives available online, such as the Sloan Digital Sky Survey and the 6 Degree Field Survey, which provide vast information on these objects.
Contacts: Stefano Ciroi

AGN and cosmology: Recent developments in understanding active galactic nuclei have identified a class of AGN exhibiting stable spectral properties over a wide range of luminosities. This class is associated with black holes accreting at very high rates. We have initiated a study of their properties across a wide range of redshifts, from 0 to 3, using survey data and proprietary data obtained with LBT and GTC. The goal is to understand their properties, including dynamics, physical conditions, and chemical composition of emission regions in optical and UV spectral lines. The stability in terms of the luminosity-to-black hole mass ratio makes these AGN potential distance indicators. In collaboration with astronomers in Italy, Spain, Mexico, China, and Serbia, we are exploring the possibility of using them to determine key cosmological parameters.
Contacts: Mauro D’Onofrio