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Recent JWST observations detected stellar clumps around the z=1.4 gravitationally lensed Sparkler galaxy (of stellar mass \\(M_*\\sim 10^9\\,\\mathrm{M_\\odot}\\)), with ages and metallicities compatible with globular clusters (GCs). However, most of their masses (\\(>10^6\\,\\mathrm{M_\\odot}\\)) and sizes (>30 pc) are about 10 times those of GCs in the local Universe. To assess whether these clumps can evolve into GCs, we performed N-body simulations of their dynamical evolution from z=1.4 to z=0 (9.23 Gyr), under the effect of dynamical friction and tidal stripping. Dynamical friction is studied performing multiple runs of a clump system in a Sparkler-like spherical halo of mass \\(M_{200}\\simeq 5\\times 10^{11}\\,\\mathrm{M_\\odot}\\) (from the stellar-to-halo mass relation). For the tidal stripping, we simulated resolved clumps, orbiting in an external, static gravitational potential including the same halo as in the dynamical friction simulations and also a Sparkler-like stellar disk. Dynamical friction causes the clumps with mass \\(>10^7\\,\\mathrm{M_\\odot}\\) to sink into the galaxy central regions, possibly contributing to the bulge growth. In absence of tidal stripping, the mass distribution of the surviving clumps (40%) peaks at \\(5\\times 10^6\\,\\mathrm{M_\\odot}\\), implying the presence of uncommonly over-massive clumps at z=0. Tidal shocks by the stellar disk strip considerable mass from low-mass clumps, even though their sizes remain larger than those of present-day GCs. When the surviving clumps are corrected for tidal stripping, their mass distribution peak shifts to \\(2\\times 10^6\\,\\mathrm{M_\\odot}\\), compatible with massive GCs. Our simulations suggest that a fraction of the Sparkler clumps is expected to fall into the central regions, where they might become bulge fossil fragments or contribute to form a nuclear star cluster. The remaining clumps are too large in size to be progenitors of GCs.

Galaxies are not isolated systems; they continuously interact with their surroundings by ejecting gas via stellar feedback and accreting gas from the environment. Understanding the interplay between outflows from the disc and the surrounding circumgalactic medium (CGM) is key to learning how star-forming galaxies evolve. Our goal is to understand how gas in the CGM is accreted onto the inner regions of the disc, making it available for the formation of stars, exploring the connection between stellar feedback and gas accretion from the CGM in Milky Way-like galaxies. We focus on the distribution of vertical and radial gas flows to and from the disc as a function of galactocentric radius, and examine the implications of these processes for the evolution of such galaxies. We use the Arepo code coupled with the SMUGGLE sub-grid model to perform hydrodynamic N-body simulations of 9 different galaxies surrounded by a hot CGM. Each simulation features a gaseous disc with different mass and scale length, allowing us to examine how disc structure impacts gas dynamics. We find evidence of a crucial link between stellar feedback and gas accretion from the CGM, which together play an essential role in sustaining ongoing star formation in the disc. In particular, the ejection of gas from the disc plane by stellar feedback leads to the generation of a baryon cycle in which the CGM gas is mainly accreted onto the external regions of the disc (\\( 3-10\\) M\\(_\\) yr\\(^-1\\) of gas is accreted into the whole disc). From these regions it is then transported to the centre with radial mass rates \\( 1-4\\) M\\(_\\) yr\\(^-1\\) on average, owing to angular momentum conservation, forming new stars and starting the whole cycle again. We find that both vertical accretion onto the inner regions of the disc and the radial transport of gas from the disc outskirts are necessary to sustain star formation.

Star-forming galaxies like the Milky Way are surrounded by a hot gaseous halo at the virial temperature - the so-called galactic corona - that plays a fundamental role in their evolution. The interaction between the disc and the corona has been shown to have a direct impact on accretion of coronal gas onto the disc with major implications for galaxy evolution. In this work, we study the gas circulation between the disc and the corona of star-forming galaxies like the Milky Way. We use high-resolution hydrodynamical N-body simulations of a Milky Way-like galaxy with the inclusion of an observationally-motivated galactic corona. In doing so, we use SMUGGLE, an explicit interstellar medium (ISM) and stellar feedback model coupled with the moving-mesh code Arepo. We find that the reservoir of gas in the galactic corona is sustaining star formation: the gas accreted from the corona is the primary fuel for the formation of new stars, helping in maintaining a nearly constant level of cold gas mass in the galactic disc. Stellar feedback generates a gas circulation between the disc and the corona (the so-called galactic fountain) by ejecting different gas phases that are eventually re-accreted onto the disc. The accretion of coronal gas is promoted by its mixing with the galactic fountains at the disc-corona interface, causing the formation of intermediate temperature gas that enhance the cooling of the hot corona. We find that this process acts as a positive feedback mechanism, increasing the accretion rate of coronal gas onto the galaxy.

The dwarf spheroidal galaxies (dSphs) satellites of the Milky Way (MW) are nearby astrophysical laboratories to study the nature of dark matter (DM). We present some properties of the DM halos of the three classical dSphs Fornax, Sculptor and Leo I, obtained using dynamical models based on distribution functions depending on the action integrals. In particular, we report accurate estimates of their central DM density rho150 (measured at a distance of 150 pc from the galaxy centre), which is relevant for galaxy formation studies and for models of self-interacting DM, and their DM annihilation J-factor and decay D-factor, which are key tools for indirect DM detection experiments. Among these three galaxies, Fornax has the highest J- and D- factors (but the lowest rho150), while Leo I has the highest rho150 (but the lowest J- and D- factors).

We present metallicity and radial velocity for 450 bonafide members of the Sagittarius dwarf spheroidal (Sgr dSph) galaxy, measured from high resolution (R~18000) FLAMES@VLT spectra. The targets were carefully selected (a) to sample the core of the main body of Sgr dSph while avoiding contamination from the central stellar nucleus, and (b) to prevent any bias on the metallicity distribution, by selecting targets based on their Gaia parallax and proper motions. All the targets selected in this way were confirmed as radial velocity members. We used this sample to derive the first metallicity distribution of the core of the Sgr dSph virtually unaffected by metallicity biases. The observed distribution ranges from [Fe/H]~ -2.3 to [Fe/H]~ 0.0, with a strong, symmetric and relatively narrow peak around [Fe/H]~ -0.5 and a weak, extended metal-poor tail, with only 13.8 +/- 1.9% of the stars having [Fe/H]< -1.0. We confirm previous evidence of correlations between chemical and kinematical properties of stars in the core of Sgr. In our sample stars with [Fe/H]>= -0.6 display a lower velocity dispersion and a higher rotation amplitude than those with [Fe/H]< -0.6, confirming previous suggestions of a disk/halo structure for the progenitor of the system.

We present new deep, wide-field Large Binocular Telescope (LBT) \\(g\\) and \\(r\\) imaging data from the Smallest Scale of Hierarchy Survey (SSH) revealing previously undetected tidal features and stellar streams in the outskirts of six dwarf irregular galaxies (NGC 5238, UGC 6456, UGC 6541, UGC 7605, UGC 8638, and UGC 8760) with stellar masses in the range \\(1.2 \\times 10^7\\) M\\(_{\\odot}\\) to \\(1.4 \\times 10^8\\) M\\(_{\\odot}\\). The six dwarfs are located 1-2 Mpc away from large galaxies, implying that the observed distortions are unlikely to be due to tidal effects from a nearby, massive companion. At the dwarfs' distances of \\(\\sim\\)3-4 Mpc, the identified tidal features are all resolved into individual stars in the LBT images and appear to be made of a population older than 1-2 Gyr, excluding the possibility that they result from irregular and asymmetric star formation episodes that are common in gas-rich dwarf galaxies. The most plausible explanation is that we are witnessing the hierarchical merging assembling of these dwarfs with their satellite populations, a scenario also supported by the peculiar morphology and disturbed velocity field of their HI component. From the SSH sample we estimate a fraction of late type dwarfs showing signs of merging with satellites of \\(\\sim\\)13\\%, in agreement with other recent independent studies and theoretical predictions within the \\(\\Lambda\\)CDM cosmological framework.

A new family of self-consistent DF-based models of stellar systems is explored. The stellar component of the models is described by a distribution function (DF) depending on the action integrals, previously used to model the Fornax dwarf spheroidal galaxy (dSph). The stellar component may cohabit with either a dark halo, also described by a DF, or with a massive central black hole. In all cases we solve for the model's self-consistent potential. Focussing on spherically symmetric models, we show how the stellar observables vary with the anisotropy prescribed by the DF, with the dominance and nature of the dark halo, and with the mass of the black hole. We show that precise fits to the observed surface brightness profiles of four globular clusters can be obtained for a wide range of prescribed velocity anisotropies. We also obtain precise fits to the observed projected densities of four dSphs. Finally, we present a three-component model of the Scupltor dSph with distinct DFs for the red and blue horizontal branch stars and the dark matter halo.

Aims. Recently, both the presence of multiple stellar chemo-kinematic components and rotation in the Sculptor dwarf spheroidal galaxy have been put into question. Therefore, we re-examine the chemo-kinematic properties of this galaxy making use of the best spectroscopic data-set available containing both line-of-sight velocities and metallicities of individual stars. Methods. We carry out a detailed, quantitative analysis on the recent spectroscopic data-set from Tolstoy et al. (2023) that contains high precision velocities and metallicities for 1339 members of Sculptor. In particular, we assess whether Sculptor is best represented by a single stellar population with a negative metallicity gradient or by the super-position of two or more components with different mean metallicity, spatial distribution and kinematic properties. For this analysis, we also include the incompleteness of the spectroscopic data-set. Results. We find that Sculptor is better described by a two-populations model than by a single-population model with a metallicity gradient. Moreover, given the assumptions of the current modeling, we find evidence of a third population, composed of few stars, that is more extended and metal-poor than the two other populations. This very metal-poor group of stars shows a shift of around 15 km/s in its average l.o.s. velocity (vlos) with respect to the rest of the galaxy. We discuss several possible origins for this new population, finding a minor merger as the most likely one. We also find a vlos gradient of 4.0 +1.5 -1.5 km s-1 deg-1 but its statistical evidence is inconclusive and, moreover, its detection is partially driven by the group of stars with off-set velocities.

Dwarf galaxies satellite of the Milky Way are excellent laboratories for testing dark matter (DM) models and baryonic feedback implementation in simulations. The Sculptor 'classical' dwarf spheroidal galaxy, a system with two distinct stellar populations and high-quality data, offers a remarkable opportunity to study DM distributions in these galaxies. In this work, we infer the DM halo density distribution of Sculptor, applying a method based on spherically symmetric distribution functions depending on actions to fit the stellar structural and kinematic properties of Sculptor. The galaxy is represented via four components: two distinct stellar populations based on distribution functions, tracers within a fixed and dominant DM potential, plus the contribution of a third stellar component that accounts for possible sources of contamination. The model-data comparison accounts for the kinematics and metallicities of individual stars, allowing us to assign probabilities of membership to each star. The modeling is applied on the largest available set of spectroscopic data, which have not been previously analyzed with this objective. We find the DM distribution of Sculptor to have a logarithmic inner slope of 0.39+0.23-0.26 and a scale radius of 0.79+0.38-0.17 kpc at 1 sigma confidence level. Our results show that Sculptor DM density profile deviates from predictions of DM-only simulations at a 3 sigma level over a large range of radii. Our analysis suggests that the velocity distribution of Sculptor's two main stellar components is isotropic in the center and becomes radially anisotropic in the outskirts. Additionally, we provide predictions for the projected radial and tangential velocity dispersion profiles. We also present updated DM annihilation and decay J- and D-factors, finding J = 18.15+0.11-0.12 and D = 18.07+0.10-0.10 for an angular aperture of 0.5 degrees.

We present new dynamical models of dwarf spheroidal galaxies (dSphs) in which both the stellar component and the dark halo are described by analytic distribution functions that depend on the action integrals. In their most general form these distribution functions can represent axisymmetric and possibly rotating stellar systems. Here, as a first application, we model the Fornax dSph, limiting ourselves, for simplicity, to the non rotating, spherical case. The models are compared with state-of-the-art spectroscopic and photometric observations of Fornax, exploiting the knowledge of the line-of-sight velocity distribution of the models and accounting for the foreground contamination from the Milky Way. The model that best fits the structural and kinematic properties of Fornax has a cored dark halo, with core size \\(r_{\\rm c}\\simeq1.03\\) kpc. The dark-to-luminous mass ratio is \\((M_{\\rm dm}/M_{\\star})|_{R_{\\rm eff}}\\simeq9.6\\) within the effective radius \\(R_{\\rm eff} \\simeq 0.62\\,\\)kpc and \\((M_{\\rm dm}/M_{\\star})|_{3 {\\rm kpc}} \\simeq 144\\) within 3 kpc. The stellar velocity distribution is isotropic almost over the full radial range covered by the spectroscopic data and slightly radially anisotropic in the outskirts of the stellar distribution. The dark-matter annihilation \\(J\\)-factor and decay \\(D\\)-factor are, respectively, \\(\\log_{10}(J\\) \\([\\)GeV\\(^2\\) cm\\(^{-5}])\\simeq18.34\\) and \\(\\log_{10}(D\\) \\([\\)GeV cm\\(^{-2}])\\simeq18.55\\), for integration angle \\(\\theta = 0.5^{\\circ}\\). This cored halo model of Fornax is preferred, with high statistical significance, to both models with a Navarro, Frenk and White dark halo and simple mass-follows-light models.