Hanbury-Brown & Twiss (1954) invented intensity interferometry and measured the size of 

some bright stars by correlating the arrival times of photons detected by two optical telescopes. 

Extremely large telescope, 10ps resolution single photon detectors bring the key improvements 

to reach in the optical angular resolutions better than these achieved in the radio by the Event 

Horizon Telescope and to obtain the first images of accretion disks around galactic compact 

objects, active galactic nuclei and quasars.

Supermassive black holes (BHs) are ubiquitous in the center of massive galaxies. When actively growing through accretion, Active Galactic Nuclei (AGNs) become some of the brightest objects in the universe. It has been two decades that relations between BH mass and the properties of their host galaxies (such as luminosity, stellar mass and stellar velocity dispersion) were first discovered. Interpreted as evidence for a co-evolution between BHs and galaxies, these scaling relations remain a hot topic for contemporary studies with many open questions remaining, including the role of AGN feedback or hierarchical merging, and the nature of the host galaxies. Studying the co-evolution as a function of cosmic history can shed light onto origin and fundamental drivers, but relies on AGNs for which host-galaxy properties are intrinsically difficult to measure, especially at higher redshift. Thus, a local baseline of the MBH-scaling relations for AGN is the key. I will discuss recent progress made possible through integral-field spectroscopy that allows for a robust measurement of stellar-velocity dispersion. While reverberation mapping has been the gold standard for BH mass measurements in AGNs, traditional methods yield only sample-average recipes for BH mass estimates. Recent advances include resolving the broad emission around AGNs spatially: (i) by dynamical modeling of reverberation-mapped data and (ii) through spectro-astronometry with GRAVITY/VLTI. The combination of both leads not only to a full 3D view of the BLR, important for accurately measuring BH mass, it even allows to measure absolute geometric distance to the AGN. In this talk, I will review our understanding of the nature and origin of the scaling relations between supermassive black holes and their host galaxies, and outline new directions.

Relativistic jets launched by supermassive black holes are among the most extreme particle accelerators in the universe. The emission from these jets is variable from radio to very-high-energy gamma-rays on timescales ranging from years to minutes. The variability patterns are extremely complex, but carry the imprint of the complex phenomenon of particle acceleration and contribution from different emission mechanisms and regions within the jet. Cherenkov Telescope Array Observatory (CTAO) will have superior capabilities to study the variability at the very highest energies. It will also allow us to study a significantly larger population of extragalactic jets than what is possible with current instruments. In this talk, I will present a few showcases to demonstrate CTAO capabilities on studies of extragalactic jets with a special focus on studies that have synergies with ESO. 

Nowadays it is possible to observe planet forming environment with incredibly high spatial and spectral resolution thanks to ALMA telescope. Recently, protoplanetary disc kinematics gained a lot of interest, as it directly probes disc structure, unveils planet disc interaction and tests the presence of hydrodynamical instabilities.

exoALMA is an ALMA large program, whose aim is to characterise the kinematics of protoplanetary environments with unprecedented spatial and spectral resolution. In this talk I will present my work within exoALMA collaboration, which involves modelling the rotation curves to constrain fundamental properties such as disc mass, stellar mass and scale radius. The knowledge of such quantities allows to investigate disc composition, to compare with thermochemical models and to constrain the efficiency of angular momentum transport.

A surprising recent result from the study of stellar rotation is that a related observational space can be constructed and stratified such that the age of a cool star can be inferred by placement therein. This procedure has distinctive parallels to the situation in geological stratigraphy. My talk will discuss how this felicitous situation came to be and how it could potentially be further developed.

The numerous discoveries of z>10 ultraviolet bright galaxies with the James Webb Space Telescope have sparked a discussion about the nature of star formation and the interstellar medium in galaxies at early times: which physical processes drove their appearance and need to be included in our models to explain them? Are these galaxies characterised by such high gas densities that stellar feedback does not hinder star formation, or do radiation-driven outflows effectively clear the dust from star-forming regions? Is their star formation highly stochastic, or do their stellar populations exhibit a higher abundance of massive stars?
We have investigated how assuming stellar initial mass functions (IMF) whose top-heaviness depends on galactic properties and/or time shapes the evolution and properties of early galaxies. To this end, we have integrated such evolving IMFs into the Astraeus framework, which couples an N-body simulation with a semi-analytical model for galaxy evolution and a semi-numerical model for reionisation. Our integration included adapting the descriptions for supernovae feedback, metal enrichment, and ionising and ultraviolet radiation emissions. 
In my talk, I will discuss how two different parameterisations of evolving IMFs affect the relations between galactic properties (e.g. stellar mass, star formation rate, ultraviolet luminosity, gas-phase metallicity), the ultraviolet luminosity functions at z=6-15, and the morphology of the ionised regions in the intergalactic medium during reionisation, compared to a constant Salpeter IMF. I will also explain which galaxies require a more top-heavy IMF to match JWST observations at z>10.

To address the need for a more realistic comparison between theory and observations, this talk will describe the creation of a synthetic spectroscopic dataset derived from the TNG50 cosmological simulation, tailored for WEAVE-StePS observations. I will compare the star formation histories of these galaxies, obtained through a full spectral fitting analysis, with their merger histories derived from the simulation. This strategy allows for a proper comparison between observed star formation histories and those inferred from cosmological simulations, highlighting potential systematics and observational biases.
This analysis serves as a fundamental benchmark not only for the forthcoming WEAVE observations but can also be easily generalized to any facility worldwide, providing the community with realistic mock galaxies to compare against observed datasets and explore optimal strategies for future extragalactic campaigns.
In the second part of the talk, I will focus on how to utilize simulations when studying star formation histories (SFH) in different environments. My project at the European Southern Observatory (ESO) aims to assess the role of the environment in shaping the SFH of galaxies by comparing data from various clusters in the local universe. The project is divided into two main aspects: analyzing observational data and comparing it with simulations.
We have already analyzed publicly available archival ESO data, such as Atlas3D (Cappellari et al., 2011) for the Virgo cluster and Fornax3D (Sarzi et al., 2018) for the Fornax cluster. While these observations provide a snapshot of the present-day universe, cosmological simulations offer comprehensive insights into the merger history, quenching, and rejuvenation processes of each galaxy. This work aims to uncover the physical processes that lead to specific SFHs, emphasizing the importance of an "apples-to-apples" comparison between observations and simulations.

I will present recent and ongoing explorations regarding cold clouds in the circumgalactic media of (simulated) z=0 Milky Way-like galaxies. We find that these CGMs are typically filled with >~100s-1000s of such cold gas structures, possibly analogs of high-velocity clouds (HVCs) observed in the Milky Way sky. These objects primarily originate as a result of cold gas outflows from the central galaxy and/or precipitation of the warm-hot phase of the CGM. Clouds arising as a result of stripping of cold gas from satellites are rare in our sample (<5%). Lastly, we find that properties of clouds are diverse, and may furthermore depend closely on their source of origin.

Majidi, F. Z. (1); Bradley, L. (2); Ma, S. (2,3); Saba, A. (2,3); Tinetti, G. (2,3);

Stotesbury, I. (2); Edwards, B. (3); Savini, G. (3); Tessenyi, M. (2)

(1) Blue Skies Space Srl., Milan, Italy; (2) Blue Skies Space Ltd., London, UK; (3) University College London, Dept of

Physics & Astronomy, London, UK

Mauve is a satellite equipped with a 13-cm telescope and a UV-Visible spectrometer (with an

operative wavelength range of 200-700 nm) conceived to measure the stellar magnetic activity and

variability. The science program will be delivered via a multi-year collaborative survey program,

with thousands of hours each year available for long baseline observations of hundreds of stars,

unlocking a significant time domain astronomy opportunity. Mauve’s mission lifetime is 3 years

with the ambition of 5 years, and will cover a broad field of regard (–46.4 to 31.8 degrees in ICRS)

during this period.

This facility was conceived to support pilot studies and new ideas in science and is fully dedicated

to time-domain astronomy. The main surveys to be executed by Mauve are long baseline

observations of flare stars, Herbig Ae/Be stars, exoplanet hosts, as well as contact binary variables

(RS CVn variables, symbiotic stars, Algol-type stars, etc.). Besides these major science themes, the

spectrometer’s data can be utilized to support and complement existing and upcoming facilities as a

pathfinder, or conduct simultaneous/follow-up observations.

The physics of gravitational instability—which links primordial density fluctuations to the formation of cosmic structures—provides the foundations for the theory of galaxy and cluster evolution. However, providing a sound description of the fate of baryons that reside within large gravitational potential wells has proven challenging. In this talk, I will present the research I conducted during my PhD—which, hopefully, I will have successfully defended the day before—focusing on the interpretation of (sub-)mm ALMA observations of the most massive gravitationally bound objects in the universe at their respective epochs: the first galaxies (at z > 10) and galaxy clusters (at z ≈ 2). I will also discuss ongoing work on a new simulation tool, named maria, designed to forecast (sub-)mm observations for current and future large single-dish facilities. Maria will be particularly insightful for next-generation sub-mm experiments like AtLAST, enabling forecasts of resolved Sunyaev-Zeldovich measurements and optically unbiased line surveys to identify high-z galaxies. These forecasts can then be directly linked to instrument and telescope design specifications, setting the stage for the future of (sub-)mm observations of cosmic structure growth.

Recent JWST observations of Type Ia supernovae (SNe Ia) during the late-time nebular phase (>200 days post explosion) have paved the way for spectroscopic studies extending all the way to the mid-infrared range, and with it the hope to better constrain SN Ia explosion mechanisms. The first SN Ia spectrum obtained with JWST unveiled for the first time the 2.5-5 micron wavelength range and revealed kinematic offsets of several 1000 km/s in a subset of emission lines, hinting at possible ejecta and composition asymmetries. The second SN Ia displayed a prominent line due to once-ionised neon ([Ne II] 12.8 micron), never observed before in spectra of such events and associated with the violent merger of two WDs. I will present the results of radiative-transfer simulations that were used to interpret these data, and discuss the impact of ejecta asymmetries, ionisation effects and uncertainties in the atomic data on the predicted spectra. These models suggest that key physical ingredients are missing from either the explosion models, or the radiative-transfer post-processing, or both. Nonetheless, they also show the potential of the near- and mid-infrared to uncover new spectroscopic diagnostics of SN Ia explosion mechanisms.

At least a significant fraction of classical Be stars were formed by past mass transfer in interacting binaries, in which they acquired the necessary excess angular momentum to spin up and form the characteristic self-ejected circumstellar disks. Post-mass-transfer Be stars typically have stripped companions of the subdwarf OB-type (sdOB), which can further evolve into white dwarfs (WD) or if massive enough into neutron stars to become high-mass X-ray binaries. Although sdOB and WD companions are expected to be common, they are very hard to detect due to their low masses and luminosities compared to the Be star primaries. Only about two dozen hot sdO companions have been detected by (far-UV) spectroscopy, with sdB and WD companions being even more elusive. In a still ongoing interferometric program on the binarity of Be stars with the CHARA Array and the VLTI, we directly detected several bloated pre-subdwarf companions, several sdO companions and we confirmed the first sdB companion with temperature similar to that of the host Be star. We also obtained astrometric orbits of these binaries with further observations, enabling the determination of their dynamical masses, and providing a firm physical basis for the associated binary evolutionary models for the first time. We were also able to shed light on the highly debated Be stars with gamma-Cas-like X-rays, with evidence mounting that they have mass-accreting WD companions. The new interferometric data also enable studying the effects that close binarity has on the structure of the Be star disks, such as the presence of circumcompanion gas and circumbinary structures.

The element compositions of resolved stars formed at distinct epochs record the chemical evolution trajectory of a galaxy. As this evolution is influenced by the galaxy-wide stellar initial mass function (gwIMF), the abundance profiles of stars offer a means to estimate the gwIMF. In this presentation, I will demonstrate the application of this methodology using the dwarf galaxy Sculptor as a case study. Specifically, I will elucidate how the gwIMF of long-lived low-mass stars intricately shapes the observed stellar metallicity distribution of a galaxy, thereby allowing for the estimation of low-mass gwIMF via galaxy chemical evolution modeling. Our analysis suggests that dwarf galaxies, characterized by low stellar metallicities and a low star formation rates, exhibits a shallower gwIMF slope for low-mass stars and a steeper gwIMF slope for massive stars (bottom- and top-light IMF). Furthermore, we have compared our findings with those derived from independent IMF estimation techniques including stellar population synthesis and star counting, illustrating a coherent and systematic IMF variation.

The intermediate-mass black hole (IMBH) regime is still poorly constrained, with few detections between 150 and 10^5 Msun. This poses a challenge to our understanding of supermassive black hole formation in the early universe.
An IMBH in ω Centauri, the Milky Way’s most massive globular cluster, has been suspected for almost two decades, but all previous detections have been questioned due to their assumptions and the possible mass contribution of a central cluster of stellar mass black holes.
I will present a new astrometric catalog for the inner region of ω Centauri, containing 1.4 million proper motion measurements based on 20 years of Hubble Space Telescope observations.
Our catalog is supplemented with precise HST photometry in 7 filters, allowing the separation of its complex subpopulations. The catalog is publicly available, providing the largest kinematic dataset for any star cluster.
Our new catalog revealed 7 fast-moving stars in the innermost 3 arcseconds (0.08 pc) of ω Centauri. The inferred velocities of these stars are significantly higher than the expected central escape velocity of the star cluster, so their presence can only be explained by being bound to an IMBH. From the velocities, we can infer a firm lower limit of the black hole mass of ∼8,200 Msun. In addition, we compare the full distribution of stellar velocities to N-Body models that suggest the presence of an IMBH with M≲50,000 Msun. These results confirm ω Centauri hosts an IMBH which makes this the nearest known massive black hole and, after the Milky Way center, only the second where we can track the orbits of multiple individual bound companions.

Our Galactic thick disk is distinct from the dominant thin disk through its unique stellar chemistry and age. However, there is no consensus on how the thin and thick disks formed and evolved, and the answer is unlikely to come from studying our Milky Way alone. Specifically, the degree to which radial mixing varies from one galaxy to another, as well as the role of star-formation-driven outflows, remains very poorly constrained. In this talk, I will present the GECKOS survey, an ESO VLT/MUSE large program of 35-edge on galaxies that aims to reveal the variation in key physical processes of disk formation. Edge-on galaxies are ideal for this task as they allow us to disentangle the assembly history imprinted in thick disks and provide the greatest insights into gas outflows. I will present the survey’s first results based on 2D measurements of stellar abundance, age, and kinematics, as well as ionised gas metallicities, ionisation parameters, and outflow kinematics — all core ingredients for chemical evolution models. In particular, I will focus on a galaxy with a newly discovered counter-rotating thick disk that may provide new insights into the long-standing question of the merger origin of the thick and thin disks. I will present a comprehensive picture of the counter-rotating galaxy’s assembly history. The most likely formation scenario is that the distinct disks resulted from a gas-rich major merger, which formed a new dominant thin disk. This theory is closely connected to one of the leading formation scenarios for our Galaxy’s thick and thin disks.

Using the IllustrisTNG and TNG-Cluster simulations, I quantify the impact of satellite galaxies on the host halo gas as functions of satellite stellar mass, host halo mass, and cosmic time. Before infall, satellite galaxies were still central galaxies with their own multiphase CGM and ISM, undergoing feedback from star-formation and/or SMBHs. As they fall into other larger hosts, ranging from MW-like galaxies to the largest clusters in the Universe, both their CGM and ISM are redistributed due to both internal feedback processes and external environmental effects, such as ram pressure stripping. Namely, satellites deposit their own gaseous reservoirs into the host halos, contributing to both the cool and hot gas in their host CGM. In particular, I follow the evolution of ~500 jellyfish galaxies in TNG50 as they deposit their cool, metal-enriched ISM into their host halos. Meanwhile, some massive cluster satellites in TNG-Cluster are able to retain their own CGM, contributing to the overall soft X-ray flux in the intracluster medium (ICM). Further, I show that the ICM today is multiphase, where clusters tend to have ~10^9-10 Msun of cool gas in their halos, according to TNG-Cluster. In the past, however, these ~350 cluster progenitors had ~10^10.5-11 Msun of cold gas, which yields observable predictions. The evolution of the cool ICM since z <~ 4, which holds for lower mass halos as well, is a complex interplay between new cool gas sources and sinks, including accretion from large scale filaments, satellite stripping, gas cooling, and gas heating via AGN feedback and virial shocks. Lastly, I discuss in-situ ICM star-formation and potential Halpha emission therefrom, and compare the MgII column density profiles in TNG-Cluster to recent SDSS stacks, where TNG-Cluster naturally produces a signficant amount of MgII absorbers.

In this talk, I will discuss some seemingly unrelated results from different observations of protoplanetary disks. I will mostly focus on our work modelling the SED of disks using an artificial neural network and what we learned by applying this to sources in Taurus. I will then describe our surprising findings when studying the nearby protoplanetary disk MP Mus with ALMA, one of the closest young solar analogues which remained relatively unexplored until recently. Finally, I will propose an alternative (and simpler) explanation for some of the disk azimuthal asymmetries that ALMA has revealed, which can help us better understand their vertical structure. Put together, these observations tell a story that suggests a solution to one of the current main issues in planet formation – only one that we may not like.

Herbig-Haro jets provide a fossil record of the accretion activity of their driving sources. In compact multiple systems this accretion can be regulated by the chaotic motion of the stars. I will give a broad overview of the dynamical processes that lead to the formation of parsec scale jets with particular reference to a new detailed study of perhaps the finest known jet complex, HH 24, based on Subaru, ALMA, HST, and JWST data.  

I will also discuss the importance of high dispersion spectroscopy in the Extremely Large Telescopes (> 30 m) era, focusing on the ANDES instrument at the European ELT, both in terms of refining our understanding of gas giants and pushing towards colder, smaller planets.

The distribution of galaxies in the universe is inhomogeneous, representing large-scale structures (LSS) that consist of galaxy clusters, groups, and the filaments that connect them. Understanding how galaxy characteristics are influenced by their environments and how they evolve over cosmic time within LSS is crucial. Utilizing narrow-band selected emitters, we investigate the environmental effects on star formation within large-scale structures. Utilizing a novel double narrow-band technique, we also explore star-forming activity and the spatial distribution of Hα and continuum emission at z=0.4, probing the cosmic web. We found that star formation in cluster core galaxies is more centrally concentrated and reduced compared to the field sample. We also explore the morphological features and star formation activities of [OII] emitters in the COSMOS UltraDeep field at z ∼ 1.5 using JWST NIRCam data from the COSMOS-Web survey and Subaru Hyper Suprime-Cam. Furthermore, we report the discovery of large filamentary structures traced by [OII] emitters, surrounding an extremely overdense core with a galaxy number density ∼ 11× higher than the field average. Heightened star-forming activity was observed in dense regions, contrary to z=0.4, suggesting an environmental impact on early galaxy evolution. Additionally, we examine the redshift evolution of star-forming activities and morphology. Future studies will explore into the chemical abundance, gas content, and kinematics to comprehend the underlying processes.

Stars of mass below that of the Sun live for sufficiently long that even in ancient systems, star-count techniques can be used to investigate the low-mass stellar Initial Mass Function (IMF). The stars in Ultra-faint dwarf (UFD) satellite galaxies in the Local Group are extremely old and extremely metal-poor and likely formed long ago in an environment very different from that of the local solar neighbourhood.  The inferred dark-matter fraction in these systems is also significantly higher than the values found in larger galaxies. Comparisons between the low-mass IMF in UFD galaxies and that of the local Milky Way thus provides insight into star-formation processes across a range of conditions and redshifts. 

I will describe our recent analyses of deep images from the Hubble Space Telescope for a set of four UFD satellites of the Milky Way plus one UFD that is likely to be a satellite of the LMC.  We conclude that there is little evidence in favour of a variable low-mass IMF. 

The Central Molecular Zone (CMZ) is an extreme environment in the inner few hundred parsecs of the Milky Way Galaxy, with temperatures, pressures, and densities exceeding those measured in the Galactic disk. At a distance of ~8.2 kpc, it has previously been difficult to perform large surveys of the CMZ at high resolution, limiting most studies to individual molecular clouds. ACES (the ALMA CMZ Exploration Survey) is a large ALMA program with high sensitivity observations covering the entire area of the CMZ at high spatial and spectral resolution at 3mm in both continuum and spectral lines. ACES data will be used to determine the overall distribution and chemical composition of mass in the inner Galaxy, from the sub-parsec scales of star formation, to the large-scale global processes that influence it. In addition, spectral line data will be used to create a comprehensive picture of gas kinematics in the CMZ, unveiling how gas flows from galactocentric radii of a few hundred pc down to the vicinity of the central supermassive black hole. Observations and high resolution hydrodynamical simulations will be used in tandem to determine how different physical processes impact the evolution of gas at different scales. We present early science results from the ACES team, including an overview of the data products, the properties of compact sources extracted using ACES continuum data, the rich chemical composition identified in the CMZ, and the characterization of gas kinematics in the CMZ. 

Ultra-diffuse galaxies (UDGs) are extremely low-surface brightness galaxies with a size of several kpc, i.e. comparable to that of the Milky Way, but with at least 100 times smaller stellar masses. In the scope of the LEWIS large programme with VLT-MUSE, we have targeted a complete sample of 32 UDG candidates in the 50-Mpc distant Hydra I cluster. In this talk, I will focus on UDG 32, a galaxy that has been hypothesised to have formed from material stripped from the nearby spiral galaxy NGC 3314a. Our new MUSE data show that NGC 3314a's filaments extend to unprecedented distances, completely engulfing the UDG and confirm that the UDG and the filaments are indeed co-spatial based in position-velocity space. UDG 32 may thus be one of the first ultra-diffuse galaxies where we catch the formation from ram-pressure stripped gas in the act.

High resolution, hydrodynamic galaxy simulations can be used to investigate the inherent variation of dark matter around the Solar Circle of a Milky Way-type galaxy. These simulations self consistently include both the baryonic back-reaction as well as assembly history of substructures, all of which may have lasting impacts on the dark matter’s spatial and velocity distributions, creating `gusts’ of dark matter wind around the Solar Circle, potentially complicating interpretations of direct detection experiments on Earth. Direct detection is a key experimental goal to advance the microscopic understanding of the dark matter that fills the Universe. We investigate how dark matter substructure, simulated in halos analogous to our own Milky Way, impacts the shape, summary statistics, and interpretation of results from terrestrial dark matter direct detectors.

Implementing a new numerical integration technique, our work generates bespoke predictions for terrestrial underground detection, finding large uncertainties arising in the expected signals of direct detection experiments. Having developed a realistic end-to-end pipeline for studying these effects, we discuss the implications of these astrophysical variations in the dark matter distribution of the solar neighbourhood on current and future particle physics searches for dark matter.

On their way from the main sequence to the final supernova explosion, massive stars lose a substantial fraction of their mass through line-driven winds. Recent decades have witnessed significant advancements in both observational and theoretical studies of these winds that sail on starlight. The advancements in our understanding of radiative driving lead to progressively more accurate estimates of mass-loss rates from massive stars. In this talk, we will outline the key ingredients necessary for reliable predictions of mass-loss rates from numerical simulations, and demonstrate how state-of-the-art theoretical mass-loss rate estimates compare with observational results.

Thanks to the recent deep observations, some massive galaxies are known to stop their star formation even just 1-2 Gyrs from the Big Bang. These early massive quiescent galaxies are likely to have obtained their stellar mass by bursty star formation within a short period and suddenly got quenched. However, their statistical properties and quenching mechanisms are still unclear. In this talk, I will introduce our recent studies to characterize massive quiescent galaxies using data from ground-based and space telescopes. 

In the first part of this talk, I will present the result of characterizing the morphology of quiescent galaxies at z>3 using the high-resolution imaging of JWST/NIRCam. We derived their sizes and Sérsic index of ~30 quiescent galaxies. For the first time, we have shown that the size is larger for more massive quiescent galaxies at z>3, as seen at z<3. Their typical sizes are ~0.6kpc at Mstar~5x10^10Msun, smaller than that at z<3; thus, significant size evolution occurred for quiescent galaxies over the last 10 Gyrs.

In the second part of this talk, I will present our study investigating the connection between quenching and AGNs at z~3-5. Using the Chandra data and the multi-band photometry of the ground-based telescopes, we conduct the stacking analysis of X-ray images of ~500 quiescent galaxies. For the first time, we detected the average X-ray emission of quiescent galaxies at z~3-5 and found that they typically have low-luminosity AGNs. Their X-ray luminosity is higher than that of star-forming galaxies, suggesting the possible connection between AGNs and quenching. Also, I will introduce our ongoing work on the detailed characterization of X-ray-detected quiescent galaxies at z~2.

The stars evolving through the asymptotic giant branch (AGB) are generally regarded as highly efficient dust manufactures, owing to the thermodynamic properties of their wind, which prove extremely favourable to the condensation process of gas molecules into solid grains. In this review I will describe the dust and mineralogy of the dust  formed in the surroundings of this class of stars, outlining the role of mass and metallicity, and the importance of these studies for the characterization of evolved stellar populations in galaxies. The contribution from the analysis of the spectral energy distribution of post-AGB stars towards a better understanding of the dust formation process by AGB stars will be also commented on.

I will present recent results from the mm-Wave Interferometric Survey of Dark Object Masses (WISDOM), a high resolution survey of molecular gas in galaxy nuclei. First, I will show that CO can be used to easily and accurately measure the masses of the supermassive black holes (SMBHs) lurking at galaxy centres. In particular, I will highlight the latest measurements, that spatially resolve the SMBHs’ spheres of influence with a few tens of resolution elements, thus leading to very precise measurements. Second, I will introduce SMBH mass-independent metrics to compare molecular gas and megamaser measurements. In turn, I will show that molecular gas observations now probe the same region of the SMBHs’ neighbourhoods, and that the mass measurements are now equally competitive. Third, if time allows, I will introduce the newly-discovered "mm fundamental plane of black hole accretion", that is surprisingly tight and holds for a wide variety of active galactic nuclei and stellar-mass black holes. This work opens the way to both precise and numerous SMBH mass measurements across the Hubble sequence (in both active and non-active galaxies) with a unique method, and thus promises to revolutionise our understanding of the co-evolution of galaxies and black holes.

In 2021 a young, solar type star underwent a complex series of eclipsing events that lasted over 900 days, preceeded by an infrared brightening seen in NEOWISE photometry some 1000 days prior to the optical eclipse. We propose that this is evidence for a collision event between an ice giant exoplanets and another exoplanet in the system, forming a luminous remnant called a `synestia’ surrounded by an expanding and cooling cloud of debris that caused the later optical eclipse. We show that Cycle 3 JWST spectroscopy will be able to confirm our models for the glowing remnant and surrounding cooler dust cloud, and discuss the implications for planet formation and evolution.

Stellar-mass black holes (BHs) are unique objects to constrain stellar and star cluster initial conditions and evolution, as they encode valuable information on their short-lived progenitor stars. If a significant fraction of BHs receive negligible natal kicks at birth, they can be retained even in open clusters with low escape velocities.

In this talk, I will present the first search for BHs in the closest open cluster to the Sun, the Hyades. I will show that the exquisite measurements by Gaia, combined with accurate N-body models, now give us the opportunity to infer signatures of even few BHs in open clusters, from the imprints they leave on the cluster’s stellar populations. For the Hyades, the observations are best reproduced by models with 2-3 BHs at present, while those that have never possessed BHs cannot match the cluster mass and size simultaneously. I will discuss how this result can provide key information on the BH natal kick distribution, one of the most crucial but still unconstrained aspects of BH formation.

Moreover, I will characterize the populations of BH-star binaries in open clusters. I will explore possible candidate stars with a BH companion in the Hyades, based on their excess error in the Gaia single-source catalog but high membership probability. Finally, I will investigate if dynamical interactions in young and open clusters can trigger the formation of Gaia BHs.

Future and ongoing infrared and radio observatories such as JWST, METIS, and ALMA will increase the amount of rest-frame IR spectroscopic data for galaxies by several orders of magnitude. While studies of the chemical composition of the interstellar medium (ISM) based on optical observations have been widely spread over decades for star-forming galaxies (SFGs) and, more recently, for active galactic nuclei (AGN), similar studies need to be performed using IR data. In the case of AGN, this regime can be especially useful given that it is less affected by temperature and dust extinction, traces higher ionic species, and can also provide robust estimations of the chemical abundance ratio N/O. Moreover, regarding (Ultra)-Luminous Infrared Galaxies ([U]LIRGs), the IR regime peers through their dusty medium and allow us to include the obscured metals in their studies. In this contribution, I will provide a summary of the bayesian-like code HII-CHI-Mistry-IR, which takes advantage of photoionization models, characterized by the chemical abundance ratios O/H and N/O, and the ionization parameter U, to compare their predicted emission-line fluxes with a set of observed values. Instead of matching single emission lines, the code uses some specific emission-line ratios that are sensitive to the above free parameters. I will also review our most recent findings from the study of IR emissions, starting from the performance of the code and its comparison to optical studies, following by a discussion on the universality of the S/O chemical abundance ratio, which can be independently estimate thanks to the set of emission lines available in this regime, and ending up by the finding of deviations from the mass-metallicity relation (MZR) as a consequence of the action of massive inflows of metal poor gas that produces that some galaxies experience a "deep-diving" phase in the MZR diagram as the metals from their ISM are diluted. 

HARPS is one of the most long-lived and proficient instruments installed at ESO telescopes. During 20 years of operation, it has produced about 800 thousand spectra, half of them of astrophysical sources and the other half of the Sun. These observations have been of paramount importance in advancing the understanding of stellar phenomena and discovery of exoplanets.

A first critical review of the observations of astrophysical sources was published in the ESO Archive as HARPS Radial Velocity catalog. This allows archive users to access the radial velocity of the targets and identify the spectral types observed, expanding the RV content using the Halpha line for RV determination.

In this talk, I will discuss the process of associating these observations with SIMBAD identifiers, a key step in cataloging and analyzing this vast dataset, and I will show how the resulting HR diagram from the HARPS RV catalog facilitates the identification of stars based on their physical characteristics.

I will also present the plan for producing a high-resolution high signal-to-noise stellar library and offer some insights into the chemical/physical and temporal characterization of this dataset.

The activity of the Sun and solar-like stars is driven by a dynamo mechanism, according to which the combination of differential rotation and convective motions of the outer atmospheric envelope continuously regenerates the magnetic field that manifests itself in the form of powerful optical, UV, and X-ray radiation. M-L dwarfs are also known to be magnetically active, but the physical mechanism is poorly understood. Studying their X-ray emission and its variability with rotation and stellar parameters allows to constrain the dynamo mechanism that powers the magnetic field and causes activity in the atmosphere.

In this talk, I present our attempt on constraining the magnetic dynamo of M dwarfs by studying the mass-dependent activity-rotation relation for the largest and most uniform sample of M dwarfs with observations taken with XMM-Newton, Chandra, eROSITA, K2 and TESS combined with X-ray and rotation data from the literature. Finally, I will present the relation between the X-ray and radio luminosity of ultracool dwarfs, and the evidences of a previously proposed bimodal dynamo responsible for the magnetic activity of these objects.

Where and how stars form within galaxies are two of the most critical questions in galaxy evolution. Our understanding of the star formation process is limited, ultimately, by our understanding of the sites of individual star formation — giant molecular clouds (GMCs). These dense, gaseous structures have sizes of 10s of pc, so the high spatial resolution required to resolve them has been mostly unattainable beyond the Local Group before the advent of the ALMA interferometer. Even then, acquiring the statistical sample of these ‘cloud-scale’ observations to answer questions like how local environment (bars, rings, etc.) module the star formation process has been an undertaking requiring 100s of hours of observing time with dedicated teams.

I will present some new results from the mm-Wave Interferometric Survey of Dark Object Masses (WISDOM) project looking at the properties of molecular clouds in ‘red and dead’ early-type galaxies, attempting to understand why these often molecular gas-rich galaxies do not form stars. We find that the molecular gas in these galaxies is often not in virial equlibrium, and external forces such as shear are likely destroying the clouds on shorter timescales than required for star formation to occur. The gas in these galaxies may be analogous to those in the Central Molecular Zone (CMZ) of the Milky Way, and provide an excellent laboratory for studying the interaction between extreme dynamics and cloud-scale properties. Combining ALMA with MUSE optical inteferometry, I have also been studying star formation on a resolved level in these quiescent galaxies. Star formation appears to be extremely localised to very small regions of the galaxy, and our integrated star formation rate measurements may be severely biased by this, with the true SFR being maybe an order of magnitude lower. However, resolved star formation efficiencies are similar to that of star forming galaxies, indicating that when star formation does happen, it perhaps happens in the same way across the galaxy population. 

The DSA-2000 will be a world-leading radio survey telescope and multi-messenger discovery engine, commencing construction in 2025. Building on proven technology developed for DSA-110, the array will consist of 2000 x 5m dishes instantaneously covering the 0.7-2 GHz frequency range, spanning an area of 19 km x 15 km in Nevada. In an initial five-year survey, the DSA-2000 will image ~33,000 deg2 repeatedly over sixteen epochs, producing a combined full-Stokes sky map with 500 nJy/beam rms noise and 3.3 arcsecond spatial resolution. Fundamental questions surrounding the baryon cycle in galaxies, the formation of stars over cosmic time, and the influence of active SMBHs on galaxies, will be addressed by detecting over a billion star-forming galaxies and active SMBHs, and by observing the neutral-hydrogen kinematics and contents of several million galaxies. The array will revolutionize the field of radio transients, detecting >10,000 FRBs, >10,000 pulsars and >1 million slow transients, with sub-arcsecond localization for host galaxy identification. The DSA-2000 will also be a leading instrument for the discovery and characterization of the electromagnetic counterparts to neutron-star mergers found by ground-based GW detectors. Overall, it will thus also serve as the radio counterpart of the Rubin-LSST survey.

ALMA has embarked upon a 150 million Euro upgrade, the so-called “Wideband Sensitivity Upgrade” or WSU, that is currently planned to be commissioned and ready for use around the end of this decade. In this talk I will outline what this upgrade means both in practical terms and for new capabilities. This is a truly massive upgrade, with essentially only the ALMA antennas staying the same. All other parts of the signal chain  - receiver bands, digitizers, data transmission system, over 40 km of optical fibres, correlator – will be replaced or upgraded to give a system with x2 to x4 increase in instantaneous bandwidth. The WSU upgrade will result in a factor of 3-6 increase in continuum mapping speed and a factor of 2-3 increase in spectral line imaging speed. Importantly, ALMA users will no longer need to sacrifice bandwidth in order to work at high velocity resolution (e.g., 0.1 km/s). For ALMA operations, a major change will be that the ALMA correlators, which are currently at >5 km altitude, will be replaced by a correlator at the ALMA Base Camp (Operations Support Facility at 3 km altitude). To meet the challenges of this era of intensive ALMA Development, for ALMA 2030 and beyond, the ESO ALMA Support Centre (EASC) has recently created a new department for Development. In this talk I will describe the new EASC structure and other ways that the EASC is stepping up to the delivery of this - in essence - brand new ALMA.

The masses of the supermassive black holes in AGNs can be determined by resolving the BH sphere of influence in time via reverberation mapping (RM). The resulting relationship between the broad-line region (BLR) radius and AGN luminosity serves as a baseline for measuring black hole mass (MBH) across the entire Universe.  For an increasing number of nearby AGNs, time-costly high signal-to-noise and high cadence RM data provide insights into BLR geometry and kinematics, offering independent MBH measurements. In combination with spatially-resolved measurements of the host galaxy kinematics, this enables us to constrain the MBH-host galaxy scaling relations with unprecedented resolution. In this talk, I will present the calibration of the MBH-stellar-velocity-dispersion relation for a sample of AGNs with velocity-resolved lags from the BLR. I will discuss the biases introduced by different aperture sizes, host galaxy morphologies, and AGN luminosities, along with the consequences for interpreting such scaling relations as tests for the black hole - host galaxy co-evolution.

The SPECULOOS (Search for habitable Planets EClipsing ULtra-cOOl Stars) project aims to perform a transit search on the nearest (< 40 pc) ultracool (<3000K) dwarf stars. The project is based on a network of 1m robotic telescopes, composed by the four ones of the SPECULOOS-Southern Observatory (SSO) in Cerro Paranal, Chile, one telescope of the SPECULOOS-Northern Observatory (SNO) in Tenerife, and the SAINTEx telescope in San Pedro Martir, Mexico. The prototype survey of the SPECULOOS project on the 60 cm TRAPPIST telescope (Chile) discovered the TRAPPIST-1 system, composed of seven temperate Earth-sized planets orbiting a nearby (12 pc) Jupiter-sized star. The project's main motivation is to discover potentially habitable planets well-suited for detailed atmospheric characterisation with James Webb Space Telescope (JWST) and the upcoming giant telescopes, like the European Large Telescope (ELT). Beside conducting observations of targets from the SPECULOOS input catalog, a fraction of the available observing time of the SPECULOOS network is used to carry out different science goals, the so-called annex programs. I will present an overview of the project, our observation strategy and the management and operations of our facilities. Finally, I will show the latest results of the survey and the synergy of our programs with the Transiting Exoplanet Survey Satellite (TESS) and JWST.

Multiple populations distinguishable by their light-element content are well studied in many globular clusters (GCs). Additionally iron spreads have been measured in some of them. In this talk an analytical method to determine the number of core collapse supernovae (CCSNe) that must have contributed to this iron spread is presented. From this the duration of star formation during the initial stage of a GC’s development can be computed. For a sample of 55 GCs with known iron spreads we find that the number of CCSNe required to explain the iron spread varies between a few tens of thousands and a few. In most cases, however, this leads to a SF duration typically around 3.5 Myr.

Przybylski's star is probably one of the most unique stars of our Galaxy. Its spectrum is overloaded with lines of s-process elements. Quantitative analysis shows that the overabundance of these elements in the Przybylski's star atmosphere is enormous. The reason for this is unknown. I will briefly discuss new ideas that may help to better understand this mysterious star and its chemical anomalies.

I will discuss recent advances in the understanding of globular star clusters from combining space-based data (Gaia parallaxes and proper motions, HST photometry) with data from large ground-based telescopes like the VLT. I will in particular discuss the initial mass function of globular clusters, the evolution of their black hole population and the possible presence of dark matter in globular clusters.