AstroBigné seminars season 2019-2020

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23/06/2020 (Google Meet)

Antonino Marasco

Massive disc galaxies in cosmological hydrodynamical simulations are too dark matter-dominated

We investigate the disc-halo connection in massive disc galaxies from the cosmological hydrodynamical simulations EAGLE and IllustrisTNG, and compare it with that inferred from the study of HI rotation curves in nearby massive spirals. We find that discrepancies between the simulated and observed discs arise both on global and on local scales. Globally, the simulated discs inhabit halos that are a factor 2 to 4 more massive than those derived from the rotation curve analysis of the observed dataset. Locally, the simulations predict dark-matter dominated galaxies with stellar-to-total enclosed mass ratios that are a factor of 1.5−2 smaller than real galaxies at all radii within the disc. This is an alternative manifestation of the 'failed feedback problem': simulated halos hosting massive discs have been too inefficient at converting their baryons into stars, possibly due to an overly efficient stellar and/or AGN feedback implementation.

09/06/2020 (Google Meet)

Teresa Fornaro

Laboratory Analog Studies for Supporting Detection of Molecular Biosignatures on Mars

The past and current exploration missions of the planet Mars have by now ascertained its past habitability. Searching for molecular biosignatures is one of the primary goals of international Mars exploration programs, because they provide more directly observable evidence of biogenicity than other categories of biosignatures for which biological production is only inferred. The ESA ExoMars 2022 rover space mission is particularly promising for detecting this kind of biosignatures because it will explore environments with higher preservation potential thanks to a drill capable of collecting samples up to a depth of two meters in the subsurface. Such more preserved samples will be analyzed with payload instruments specifically designed to detect organics. A critical assessment of the potentialities and limitations of these space flight instruments in detecting agnostic features of molecular biomarkers provides a fundamental support to the interpretation of space mission data. Such a comparative analysis can be done through detectability/sensitivity tests using highly characterized Mars soil analog samples prepared in the laboratory under controlled conditions mimicking processes occurring on Mars. Here I briefly report a summary of the results obtained from combined science investigations of laboratory analog samples using MicrOmega, RLS and MOMA instruments. This study paves the way for building a "custom" database of diagnostic features observable with the ExoMars payload instruments of the major classes of molecular biomarkers embedded in mineral matrices that are the most relevant to the Oxia Planum landing site, tailored to support ExoMars science operations in the field.

26/05/2020 (Google Meet)

Jacopo Soldateschi

Iron Line from Neutron Star Accretion Disks in Scalar Tensor Theories

The Fe Kα fluorescent line at 6.4 keV is a powerful probe of the space-time metric in the vicinity of accreting compact objects. In this talk I will explain how some alternative theories of gravity, namely Scalar Tensor Theories, that invoke the presence of a non-minimally coupled scalar field and predict the existence of strongly scalarised neutron stars, change the expected line shape with respect to General Relativity. By taking into account both deviations from the general relativistic orbital dynamics of the accreting disk, where the Fe line originates, and the changes in the light propagation around the neutron star, we computed line shapes for various inclinations of the disk with respect to the observer. We found that both the intensity of the low energy tails and the position of the high energy edge of the line change. Moreover we verified that even if those changes are in general of the order of a few percent, they are potentially observable with the next generation of X-ray satellites.

19/05/2020 (Google Meet)

Giovanni Poggiali (astrobiology)

OSIRIS-REX sample return mission toward its final step. Latest results from the Science Team and Arcetri group

The Origins, Spectral Interpretation, Resource Identification, and Security-Regolith Explorer (OSIRIS-REx), NASA sample return mission is orbiting the primitive asteroid (101955) Bennu since December 2018. After a detailed study of the surface the mission is now approaching the challenging step of its main objective: the sampling of the surface and the returning safely to Earth. The first sampling attempt will be performed later this year and now the mission is performing a series of rehearsals to test the critical manoeuvre. Many exciting results were performed by the Science Team using the instrument suite on board the spacecraft. Between major results we must cite the observation of particles ejection events revealing an active nature for the asteroid. Arcetri astrobiology and planetary group contributes to the spectroscopic analysis of the surface both supporting science team analysis with laboratory measurements and investigating remote sensing data collected by the infrared spectrometers. In my presentation I will give an overview of the mission and I will review latest results focusing on the contribution of Arcetri group.

12/05/2020 (Google Meet)

Matilde Mingozzi

Probing ISM properties in local star forming galaxies with the MaNGA survey

Investigating how the content of chemical elements evolves through cosmic time and relating it to other observables provides unique information on the evolutionary processes driving the formation and evolution of galaxies. Because of this connection, the distribution of gas-phase metallicity in the interstellar medium (ISM) of galaxies provides a strong constraint on their growth and formation and recent dynamical processes. An important limitation in determining metallicity could be the secondary dependence of the most used metallicity diagnostics on other parameters of the ISM, such as the ionization parameter (i.e. a measure of the ionizing photons with respect to the gas density). In this context, we calculated self-consistently metallicity, ionization parameter and dust extinction for a representative sample of ~1800 local star forming galaxies using integral field spectroscopy from the MaNGA survey. Physical parameters of the ionized ISM are derived by a Bayesian framework, that compares observed lines fluxes with predictions from photoionization models. In this talk, I will discuss how the still poorly understood ionization parameter varies within galaxies of different stellar masses and as a function of metallicity, exploiting the statistical power of the MaNGA survey.

 05/05/2020 (Google Meet)

Antonio Garufi

Imaging the cradle of planets, as soon as possible

There is growing evidence that the planet formation occurs very soon in the protoplanetary disks, possibly before these disks 'hatch' from the natal envelope of the protostar. In Arcetri, we are carrying out the ALMA-DOT campaign, devoted to the chemical characterization of these embedded sources. I present the results of the survey, shedding light on the timescale for the formation of dust and gas sub-structures, the morphological interplay of dust and gas, and the distribution and formation mechanism of simple organic molecules.

28/04/2020 (Google Meet)

Maria Tsantaki

Possible scenarios of Li-rich giants observed in open clusters

Lithium is expected to be fully depleted in red giants due to the dilution they experience during their first dredge-up. However, several Li-rich giants have been observed in the field as well as in clusters with their origin still under discussion. In this work, we explore the Li content of giant stars in 17 different open clusters with high-resolution spectroscopy from the La Silla facilities (R=110000) in Chile. We used the spectral synthesis technique to obtain precise Li abundances for 157 giant stars and found 6 red giants showing clear Li enhancement in 3 open clusters. We infer their evolutionary stage to show that our Li-rich stars occupy different regions in the HR diagram. In some cases, they lie near the luminosity bump, where Li is produced by the Cameron-Fowler mechanism and fresh Li is brought to the surface by extra mixing. In other cases, these stars are more evolved in the He-burning phase, or approach the asymptotic giant branch. Our sample is part of the planet search program with some giants to have detected substellar companions (Delgado-Mena et al. 2018). An interesting scenario we evaluate in this work is the possibility that Li enhancement is triggered by the engulfment of a close-in sub-stellar object which initiates an extra-mixing process to bring Li in the stellar photosphere.

14/04/2020 (Google Meet)

Mauro Focardi (technology)

The short and adventurous (in-space) life of a PLATO Science telemetry packet

PLATO has been selected and adopted by ESA as the third Medium-class mission of the Cosmic Vision Program to be flown in late 2026. It will detect and characterise exoplanets by means of their transit signature in front of a very large sample of bright stars, and will measure the seismic oscillations of the parent sun in order to understand the properties of exoplanetary systems down to rocky planets orbiting solar-like stars in their habitable zone. To achieve its main scientific goal, the PLATO Instrument, similarly to most other scientific payloads, has been designed to collect and transmit to Ground the raw scientific data in a complex and efficient way that requires a huge engineering work on HW and SW, sometimes unknown or overlooked by the Scientific Community in charge of exploiting the produced data. So, with my talk, I will try to highlight the "short and adventurous" life of a PLATO scientific telemetry packet, across the P/L HW and SW layers, before its transmission to Ground.

07/04/2020 (Google Meet)

Giulia Macario (SKA)

Early results from the SKA1-low station prototype AAVS2.0

In this talk I will present the first results obtained since the beginning of my post-doc activity at OAA, last November. The SKA's low-frequency array, SKA1-Low, will observe the radio sky between 50 and 350 MHz with unprecedented sensitivity and angular resolution. The Aperture Array Verification System 2 (AAVS2) is a new prototype station of SKA1-Low operational at MRAO (Australia) since December 2019, that is being tested before the construction phase (late 2020). I will show some of the first all-sky images at low-frequencies obtained with AAVS2. I will also present a preliminary estimate of SKA1-Low sensitivity obtained from AAVS2 data at 160 MHz, that is in agreement with the SKA1-Low requirement.

31/03/2020 (Google Meet)

Laura Colzi (star formation)

Enhanced nitrogen fractionation at core scales: the high-mass star-forming region IRAS 05358+3543

It is well known that the 14N/15N isotopic ratio measured for the proto-Solar nebula (PSN), 440, is significantly higher than that measured in pristine Solar System materials, like comets (140). This suggests a local chemical enrichment of 15N during the Sun formation process. However, the cause of this enrichment and its relationship with the natal clump are still uncertain. Since there is growing evidence pointing out that our Sun was born in a rich cluster contained massive stars, during my PhD thesis I have studied the 14N/15N ratio in a large sample of high-mass star forming regions. In particular, in this talk I will first show the overall behavior of the 14N/15N ratio across the Galaxy (Colzi et al. 2018a,b). We have confirmed, based on a solid statistics for the first time, that the 14N/15N ratio increases with the Galactocentric distance as a consequence of the Galactic chemical evolution. Then, I will zoom-in into the massive star-forming protocluster IRAS 05358+3543. I have obtained the first interferometric maps of N-fractionation combining single-dish and high-resolution interferometric observations of the 15N-isotopologues of N2H+ (Colzi  et al. 2019). The analysis yields 14N/15N ratios of 100-200 in the cores, and higher values of about 200 in the diffuse clump gas. This result, which strongly suggests a local chemical enrichment of 15N at core-scales, helps us to understand how the chemical inventory evolves from the parental molecular reservoir to smaller-scale objects, in which star-formation occurs.

25/02/2020

Armando Riccardi (adaptive optics)

Adaptive Optics module of ERIS left Arcetri to Garching: a step toward the full instrument integration

The adaptive optics module of ERIS, the new IR instrument for the VLT, recently passed the acceptance test in Arcetri. One week ago was finally packed and shipped to the Max Planck Institute in Garching for the integration with the science instruments, the NIX camera and the SPIFFIER spectrograph. The talk briefly reports the current status of ERIS and the next steps toward the fully integrated instrument preliminary acceptance in Europe (PAE) before the shipping to Paranal. 

11/02/2020

Viola Gelli (extragalactic)

The stellar populations of high-redshift dwarf galaxies

We use state-of-art cosmological zoom-in simulations of a typical z ∼ 6 Lyman Break Galaxy (LBG) with a stellar mass M⋆ ≃ 1010M⊙ to investigate the stellar properties of its dwarf galaxy satellites. We find six of them residing in the host galaxy halo, their stellar masses ranging from M⋆ ≃ 106M⊙ to ≃ 109M⊙ and their gas mass from Mgas ≃ 2 × 104M⊙ to ≃ 5.5 × 107M⊙. The properties and evolution of all the dwarf satellites show no dependence on the distance from the central massive LBG (< 11.5 kpc). Indeed, their star formation and chemical enrichment histories reveal that the main driver of their evolution is the stellar (and halo) mass. High-mass dwarf galaxies (M⋆ > 5 × 108M⊙) experience a long history of star formation, characterised by many merger events. Their first star-forming progenitors appear at z ≈ 12 and form stars out of pristine gas. Low-mass systems (M⋆ < 5 × 108M⊙) are instead characterised by much simpler and shorter SFHs, with no signs of mergers. Their star formation activity starts at later epochs (z ≈ 7) from an already chemically enriched gas but it is rapidly quenched because of the strong influence of the internal stellar feedback and the dissociating radiation from the nearby star-forming LBG. In spite of the different evolutionary patterns, all systems show a spherical morphology, with ancient and more metal-poor stars located towards the inner regions. In addition, all these dwarf satellite galaxies experienced high SFRs bursts (typically > 5M⊙ yr−1), which means that the James Webb Space Telescope will be most likely able to detect them while targeting high-z LBGs.  

Martina Rossi (extragalactic)

Constraining the low mass end of the first stars 

The precise value of the lower-mass limit of PopIII stars is important in predicting whether any truly metal-free stars could have survived until present-day. Therefore, we investigate the frequency of first stars relics in Ultra-faint dwarf galaxies to limit the low-mass end of the Initial Mass Function (IMF) of the first stars. To this end we develop a theoretical model that follows the formation and evolution of isolated Ultra-Faint dwarf galaxy, particularly focusing on the best studied system: Boötes I. We calibrate the model by comparing our results with available observations (galaxy Luminosity, Metallicity Distribution Function, and Star Formation History) and we detailed studied how the incomplete sampling of the stellar IMF affects the chemical evolution of poorly star-forming Ultra-Fain dwarf galaxies. We explore the impact of different PopIII IMFs on the expected number of long-living first stars in Boötes I and, by exploiting available data, we provide observational-driven constraints on the minimum mass of the first stars.

28/01/2020

Asa Skuladottir (extragalactic)

Evidence for ≳ 4 Gyr timescales of neutron star mergers from Galactic archaeology

The nucleosynthetic site of the rapid (r) neutron-capture process is currently being debated. The direct detection of the neutron star merger GW170817 has confirmed such events as important site of the r-process. However, the long estimated timescales for this event are at odds with chemical evolution models of the Milky Way, which are only able to reproduce the observed abundances if short time-delays of the r-process are assumed. Different scenarios have been invoked to solve this discrepancy, but none of these can self-consistently explain the observed r-process abundances in several galaxies at once. The key to solving this puzzle is therefore to combine all the available evidence in the Milky Way and its dwarf satellite galaxy. This data can only be explained if there are (at least) two distinct r-process sites: a quick source with timescales comparable to core-collapse supernovae, ≲ 108 yr, and a delayed source with characteristic timescales ≳ 4 Gyr. The delayed r-process source is most probably neutron star mergers, as the timescale fits well with that estimated for GW170817. Given the short timescales of the quick source, it is likely associated with massive stars, though a specific fast-track channel for compact object mergers cannot be excluded at this point.

Simone Bianchi (extragalactic)

The time signal in Florence

I review a century of time signal in Florence, starting from the 1850s when true solar time from the clock on the tower of Palazzo Vecchio was transmitted telegraphically to the railway stations of the Grand Duchy of Tuscany. At the onset of Italian Unification, midday was signaled to the city by means of a flag lowered on the Torrino, the tower of the old Astronomical Observatory of Florence. In the short period when Florence was the Italian Capital (1865-1871), the time signal from the Torrino served to regulate communication and transport services in the nation; after that, it continued as a city service only. At the end of the 19th century, the flag was substituted by the firing of the votapentole cannon from the Belvedere Fortress. From the Great War, the service began to be regulated by the astronomers of the newer Arcetri Observatory. Except for a brief interruption during the Second World War, the time signal continued until the early 1950s.

14/01/2020

Giovanni Morlino (high energy)

Contribution of starburst nuclei to the diffuse gamma-ray and neutrino flux

In nuclei of starburst galaxies, the combination of an enhanced rate of supernova explosions and a high gas density suggests that cosmic rays can be efficiently produced, and that most of them lose their energy before escaping these regions, resulting in a large flux of secondary products, including neutrinos. Although the flux inferred from an individual starburst region is expected to be well below the sensitivity of current neutrino telescopes, such sources may provide a substantial contribution to the diffuse neutrino flux measured by IceCube. Using a physically motivated model, I will show that starburst nuclei alone can account for the observed diffuse neutrino flux above 200 TeV, while below such energy additional contributions are needed which can be possibly provided by Galactic sources or atmospheric neutrinos.

Valdemaro Biliotti (tecnology)

The control electronics for the Amici Telescope

Nel talk sarà descritto il sistema di controllo assi per il telescopio, non dimenticando i criteri che hanno guidato le scelte del progetto, e come queste sono state implementate al telescopio.

26/11/2019

Giada Casali (stellar group)

Stellar dating using [C/N] as chemical clock

In the era of large high-resolution spectroscopic surveys such as Gaia-ESO and APOGEE, high-quality spectra can contribute to our understanding of the Galactic chemical evolution by providing abundances of elements that belong to the different nucleosynthesis channels, and also by providing constraints to one of the most elusive astrophysical quantities: stellar age. Some abundance ratios, such as [C/N], have been proven to be excellent indicators of stellar ages. We aim at providing an mpirical relationship between stellar ages and [C/N] using open star clusters, observed by the Gaia-ESO and APOGEE surveys, as calibrators. Finally we apply our relationship to selected giant field stars in the Gaia-ESO and APOGEE surveys. With this empirical relationship, we are able to provide an age estimate for giant stars in which C and N abundances are measured. Our method can therefore be considered as an additional tool to give an independent estimate of the age of giant stars.

Paolo Tozzi (outreach)

Tutto quello che avreste voluto sapere sulle Notti d'Estate

Comunicare la scienza in forma spettacolare è sempre più spesso una modalità apprezzata dal grande pubblico. Nelle Notti d'Estate ad Arcetri, cerchiamo da anni di coniugare un contenuto scientifico di alta qualità con un format vicino a quello di un festival. Daremo uno sguardo alle Notti d'Estate 2019, e alle  prospettive per il 2020.

12/11/2019

Antonino Marasco (extragalactic)

Extra-planar HII and galactic fountain cycle in nearby late-type galaxies

In the last two decades, deep HI observations of nearby late-type galaxies have revealed the presence of extra-planar HI layers extending up to a few kpc above the galaxy midplane and accounting for ~10% of the total HI content. In the few cases studied in detail, these HI layers were found to be characterised by a slow-rotating, globally inflowing kinematics, which is expected by gas in a galactic fountain cycle triggered by stellar feedback. We now present a homogenous and detailed analysis for a sample of 13 late-type galaxies with deep HI observations from the HALOGAS project. For each system we have masked out the HI emission coming from the rotating thin disk and produced synthetic data-cubes to model the leftover extra-planar emission. Our model features 3 structural and 4 kinematical global parameters, which are fit to the data via a Bayesian MCMC method. We found that extra-planar HI layers are ubiquitous in disc galaxies, with HI masses that are in excellent agreement with predictions from simple models of galactic fountain powered by stellar feedback. In most cases, the kinematics show a global inflow with speed of 20-30 km/s in the vertical and radial directions, along with a vertical rotational lag of 5-20 km/s/kpc, suggesting an interaction between the material outflowing from the disc and the circumgalactic medium.

Giacomo Venturi (extragalactic)

The role of AGN outflows and jets from isolated to merging galaxies

Active galactic nuclei (AGN), through the effect of outflows and jets, are believed to play a major role in the formation and evolution of their host galaxies, by sweeping away the gas and quenching star formation. In the so-called "radio-loud" AGN, relativistic jets are considered important actors in shaping the host galaxy properties by interacting with its interstellar medium (ISM) and accelerating massive outflows. However, by inspecting nearby "radio-quiet" Seyfert galaxies in detail with MUSE at VLT, we found that also low-power AGN jets can have a significant impact on the galaxy ISM, with some unexpected peculiar effects and potentially important implications!
Finally, I will present a highlight on a recently started project which, by targeting galaxies across different merging stages, aims to investigate the role of mergers in launching outflows, triggering AGN activity and exerting feedback on the intense star formation in the host galaxies, from galactic down to nuclear scales (through a combination of wide-field and AO-assisted VLT/MUSE observations).

29/10/2019

Stefano Menchiari (high energy)

Development of a robust algorithm for source detection in very high energy gamma-ray surveys of the Galaxy

In the next decades, with the new generation of gamma-ray telescopes such as the upcoming Cherenkov Telescope Array (CTA), we will be able to investigate the high energy sky as never before. One of the main scientific goals of CTA is to create the deepest and most complete Galactic plane survey, composed of more than 1500hrs of observation. Thanks to the excellent sensitivity of CTA, the survey will be able to probe deeply the Milky Way plane, allowing us to explore the whole Galactic disk and to detect the faintest sources. As the detection sensitivity will improve, the problem of confusion between overlapping sources along the line-of-sight will grow. The correct identification of as many sources as possible is of primary importance, not only to better constrain their individual properties but also to avoid biasing source population studies. We present the development of a robust multi-template fitting algorithm for the study of candidate gamma-ray sources in surveys of the Galactic plane. The developed code, in combination with a seeking algorithm used to detect gamma-ray excesses, creates a catalog pipeline for the analysis of surveys. The presented algorithm is capable of making morphological classification and calculating the statistical significance of source candidates using a sequential multi-template fitting strategy, which consists in testing all the objects detected by the seeking algorithm with different morphological templates, such as Gaussian, shell-like shapes and also a combination of two 2D Sersic profiles. As the latter is able to reproduce several kinds of morphologies, the resulting fitted parameters are used for the classification purpose. We will illustrate the detection and fitting performance of the algorithm using the simulated CTA Galactic Plane Survey (DC-1). As a result, we found both high-grade fit quality and detection efficiency for TeV emitting objects such as PWNe, SNRs, and composite sources. We also obtained satisfactory results in the case of statistically non-significant extremely faint sources. 

Francesca Brunetti (biblioteca)

Orientarsi in biblioteca: la strada più veloce per accedere alle risorse informative

La biblioteca di Arcetri è un polo di un'unica grande biblioteca geograficamente distrbuita, accessibile da Polvere di Stelle: il portale dei beni culturali dell'astronomia italiana. Un patrimonio informativo a disposizione di ricercatori, di studiosi, di studenti e di appassionati della materia. Come orientarsi, quali strumenti usare per avere a disposizione nel minor tempo possibile le risorse informative che cerchiamo?

15/10/2019

Rossella Spiga (comunicazione)

La comunicazione scientifica all'Osservatorio di Arcetri - le basi di un piano d'azione congiunto

Input sulla strategia locale e nazionale per la comunicazione delle attività scientifiche e di outreach dell'Osservatorio Astrofisico di Arcetri. Presentazione delle attività dell'ufficio comunicazione da implementare in sinergia con i gruppi di ricerca locali e con la struttura nazionale INAF per la comunicazione.

Salvatore Ferrone (Ithaca College)

Spectral and Physical Properties of High Reflectance Boulders on the Surface of NASA'S OSIRIS-REx Target Asteroid 101955 Bennu

The OSIRIS-REx asteroid sample return mission is currently in the reconnaissance phase in which target sample sites on Rubble Pile Asteroid 101955 Bennu are being studied in close proximity and at high resolution. The spacecraft is equipped with high resolution imagers as well a visible and near infrared spectrometer. In this study, we present global spectroscopic analysis of Bennu to probe if there is a relationship between spectral and geologic features. Results to date indicate (1) distributions of spectral properties are single peaked and skew; and (2) that correlations of these spectral properties with surface textures are weak. This could imply there is only one boulder population on Bennu, which would support a formation process of a disruption event of a parent body over a collision between two smaller parent bodies. The skewness of the distribution of the spectral features on Bennu could imply space weathering, which is an optical alteration of the surface due to exposure to solar particles, galactic particles, and micro-meteorites impacts. If we are able to provide enough evidence in support of space weathering driving the spectral variations, we may be able to form age relationships on Bennu.

01/10/2019

Premiazione del Premio Magini: Marco Cilibrasi (UniPi)

Satellites Form Fast & Late: a Population Synthesis for the Galilean Moons

The satellites of Jupiter are thought to form in a circumplanetary disc (CPD), i.e. a small disc forming around a giant planet when a gap is opened in the protoplanetary disc. We study the formation and orbital evolution of moons with a population synthesis approach, by varying the dust-to-gas ratio, the disc dispersal timescale and the dust refilling timescale in such a disc. The CPD initial conditions (density and temperature) are directly drawn from the results of 3D radiative hydrodynamical simulations. The disc evolution is taken into account within the population synthesis, and the satellitesimals were assumed to initially grow via streaming instability, then via dust accretion, while they migrate through the disc.
We find that the moons form fast, often within 104 years, due to the short orbital timescales in the disc. They form in sequence, and many are lost into the planet due to fast type I migration, polluting Jupiter’s envelope with typically 15 Earth-masses of metals. The last generation of surviving moons can form very late in the evolution of the giant planet when the disc has already lost more than 99% of its mass. The late circumplanetary disc is cold enough to sustain water ice, hence not surprisingly 85% of the moon population has icy composition. The distribution of the satellite-masses is peaking slightly above Galilean masses, up until a few Earth-masses, in a regime which is observable with the current instrumentation around Jupiter-analog exoplanets orbiting sufficiently close to their host stars.

Antonio Pensabene (UniFi)

The ALMA view of the high redshift relation between supermassive black holes and their host galaxies

The existence of tight correlations between supermassive black holes (BHs) and their host galaxies properties in the local Universe suggests a closely linked evolution. Investigating these relations up to the high redshifts (z > 6) is thus crucial to understand the interplay between star-formation and BH growth across the cosmic time and to set constraints on galaxy formation and evolution models. In this work, I present the relation between black hole mass (MBH) and the host galaxy dynamical mass (Mgal) for a sample of 10 high-z (z ~ 2 – 7) quasars for which we have obtained measurements of the host galaxy kinematics from archival data of the Atacama Large (Sub-)Millimeter Array (ALMA). Thanks to the unparalleled capabilities of ALMA, we are now able to spatially resolve the kinematics of cold gas traced by bright atomic/molecular lines such [CII] or CO and measure the galaxy masses through a full kinematical modelling of galaxy disks even at the highest redshifts, thus avoiding all possible biases and effects introduced by the rough estimates usually adopted so far (photometric measurements of stellar masses, virial estimates, etc.). Up to redshift z ∼ 5, the MBH/Mgal ratio is consistent with the extrapolation of the relation inferred at z < 3. At z > 5 we find a steady decrease of the MBH/Mgal ratio with increasing redshift, possibly witnessing the phase of fast growth of the BHs compared to the host galaxies. I will discuss how these results fit within the coevolution scenario and highlight the constraints that they pose on models of galaxy evolution.

Elisabeta Lusso (UniFi)

Visit to the telescope complex of La Palma

For the third year, the astrophysics students of the course of Complementi di Astronomia visited El Roque de Los Muchachos telescopes in La Palma to experience how the ground-based telescopes work in one of the most important observing sites in the world. They also had the opportunity of spending an observing night at the TNG acquiring data on extragalactic targets, selected by them and later analyzed during the laboratory classes.

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