The morphology of haloes can inform about both cosmological and galaxy formation models. By computing the Minkowski Functionals of the continuous body suitably dressing the dark matter halo particles, one can completely characterize the morphology of haloes without assuming any symmetry like sphericity or ellipticity. The drawback is the lack of analytical MFs for realistic particles distributions. As a remedy, we turn to synthetic haloes with analytical density profiles, recovering a consistent interpretation of MFs with respect to well-known parameters such as inner and outer slope, concentration and sphericity. We also show that the MFs seem to capture more information than these parameters.

The X-ray Integral Field Unit (X-IFU) onboard the second large EAS mission "Athena" will be a high spatial (5") and spectral (2.5 eV) resolution X-ray imaging spectrometer, operating in the 0.2-12 keV energy band. It will address the science question of the assembly and evolution through cosmic time of the largest halos of matter in the Universe, groups and clusters of galaxies. To this end, we present an on-going feasibility study to demonstrate the X-IFU capabilities to unveil the physics of massive halos at their epoch of formation. Starting from a distant (z=2) group of galaxies (7E13 M_sun) extracted from the HYDRANGEA cosmological and hydrodynamical numerical simulations, we perform and end-to-end simulation of X-IFU observations. From the reconstruction of the global, 1D and 2D quantities, we investigate the various X-IFU science cases for clusters of galaxies, such as the chemical enrichment of the intra cluster medium, the dynamical assembly of groups and clusters and the impact of feedback from galaxy and super-massive black hole evolution.

The Gaia EDR3 has provided a considerable accuracy improvement for calculating the orbital energy and angular momentum of Milky Way dSphs. Here we show that their total energy and angular momentum distinguish them from Milky Way K-giant stars, Sagittarius stream stars and globular clusters. It also led to the discovery of a new and strong relationship between dSphs belonging to the Vast Polar Structure of Satellites (VPOS). This suggests that many dSphs are accompanying the Magellanic Clouds in their first infall to the Milky Way.

Due to an environment that promotes gravitational interactions and ram pressure stripping, galaxies within clusters are particularly likely to present unusual interstellar medium properties. NGC~4654 is a Virgo cluster galaxy which undergoes gas ram pressure stripping and a fly-by gravitational interaction with another massive galaxy, NGC~4639. NGC~4654 shows a strongly compressed gas region, with HI surface densities significantly exceeding the canonical value of 10-15 Msol/pc2. New IRAM 30m HERA CO(2-1) data of NGC~4654 are used to study the physical conditions of the ISM and its ability to form stars in the region where gas compression occurs. We observe a significant decrease in the ratio between the molecular fraction and the total ISM pressure in the high HI surface density region. Analytical models were used to reproduce radial profiles of the SFR and the atomic and molecular surface densities to better understand which physical properties are mandatory to maintain such high HI surface density region (low Toomre parameter Q, high velocity dispersion). A dynamical model that takes into account both interactions was used to reproduce the gas distribution of NGC~4654. We find that the model SFR is underestimated in the high HI surface density region due to the absence of gas cooling and stellar feedback in the dynamical model. During a period of gas compression through external interactions, the gas surface density is enhanced, leading to an increased SFR and stellar feedback. Our observations and subsequent modeling suggest that, under the influence of stellar feedback, the gas density increases only moderately. The stellar feedback acts as a regulator of star-formation, significantly increasing the turbulent velocity within the region. 

Structure in our universe grow hierarchically, where small structures (stars and galaxies) assemble first and later on galaxies group/proto-clusters together in large potential wells to form clusters. Clusters of galaxies are the largest structure observable in our Universe and can contain more than hundreds of galaxies. We believe that every galaxy carries its own small halo of dark matter, and when they fall in a cluster part of that halo is stripped and diffused in the larger halo of the cluster. I will present here, how I am using the strong gravitational lensing effect in combination with IFU of cluster fields to answer questions on the evolution of the halos and sub-halos dark matter components. Indeed galaxies and their dark matter falling in the cluster and losing their dark matter to the profit of the cluster also called the sub-halos mass loss. In the futur I will use a large number of models spanning a wide range of redshifts (0.3 < z<1.0) to show how cluster transfer their mass from their cluster members to their host halos.

It is now rather well assessed that both the nodes of the cosmic web and the filaments affect galaxy properties and influence their evolution. Galaxies experiencing either the node or the filament environment have reduced star-formation activity and become quiescent, while also being more massive than galaxies in the field. At the same time the rotation (spin) of galaxies is generated and influenced by the tidal field of the cosmic web, with low-mass galaxies that are born with their spin aligned to filaments and that progressively change its orientation while they flow towards the nodes, resulting in high-mass galaxies having their spin perpendicular to the filaments when they reach clusters. Indeed, the presence of a well established red sequence of galaxies is a clear indication of structure (e.g. a cluster) and one could argue that star-formation quenching or the spin of galaxies could also be used to better trace filaments. We resort to a numerical simulation (Illustris-TNG) and a cosmic web detection algorithm (the Discrete Persistent Structure Extractor, DisPerSe) to test the relative effect of nodes and filaments on star-formation quenching and spin alignment in simulated galaxies. The goal is to determine which galaxy property is dominated by which kind of structure (nodes or filaments) and to test if anisotropic properties of galaxies such as the orientation of the rotation axis are more influenced by structures which present a preferential direction (such as filaments) while isotropic, scalar quantities (such as star-formation activity) resent more of structures that do not have a strong asymmetry such as (approximately) spherically symmetric nodes. Our findings suggest that, although present, the effect of filaments and nodes on the alignment of galaxy spin is a secondary effect. Star-formation is the quantity that varies the most with the distance to filaments and nodes. Correspondingly, detecting variations in the fraction of quenched galaxies is a powerful way to trace the structures of the cosmic web.

Given their prominent role in galaxy evolution, it is of paramount importance to unveil galaxy interactions and merger events and to investigate the underlying mechanisms. The use of high-resolution data makes it easier to identify merging systems, but it can still be challenging when the morphology does not show any clear galaxy-pair or gas bridge. Characterising the origin of puzzling kinematic features can help to reveal complicated systems. Here, we present a merging galaxy, MaNGA 1-114955, in which we highlighted the superimposition of two distinct rotating discs along the line of sight. These counter-rotating objects both lie on the star-forming main sequence but display perturbed stellar velocity dispersions. The main galaxy presents o-centred star formation as well as o-centred high-metallicity regions supporting the scenario of recent starbursts, while the secondary galaxy hosts a central starburst which coincides with an extended radio emission, in excess with respect to star formation expectations. Stellar mass as well as dynamical mass estimates agree towards a mass ratio within the visible radius of 9:1 for these interacting galaxies. We suggest we are observing a pre-coalescence stage of a merger. The primary galaxy has accreted gas through a past first pericentre passage about 1 Gyr ago, and more recently from the secondary gas-rich galaxy, which exhibits an underlying AGN. Our results demonstrate how a galaxy can hide another one and the relevance of a multi-component approach to study ambiguous systems.We anticipate our method to be ecient at unveiling the mechanisms taking place in a sub-sample of galaxies observed by MaNGA, all exhibiting kinematic features of puzzling origin in their gas emission lines.