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We present the first set of high-resolution, hydrodynamical cosmological simulations of galaxy formation in a Fuzzy Dark Matter (FDM) framework. These simulations were performed with a new version of the GASOLINE2 code, known as FUZZY-GASOLINE, which can simulate quantum FDM effects alongside a comprehensive baryonic model that includes metal cooling, star formation, supernova feedback, and black hole physics, previously used in the NIHAO simulation suite. Using thirty zoom-in simulations of galaxies with halo masses in the range $10^9 \lesssim M_{\text{halo}}/M_{\odot} \lesssim 10^{11}$, we explore how the interplay between FDM quantum potential and baryonic processes influences dark matter distributions and observable galaxy properties. Our findings indicate that both baryons and low-mass FDM contribute to core formation within dark matter profiles, though through distinct mechanisms: FDM-induced cores emerge in all haloes, particularly within low-mass systems at high redshift, while baryon-driven cores form within a specific mass range and at low redshift. Despite these significant differences in dark matter structure, key stellar observables such as star formation histories and velocity dispersion profiles remain remarkably similar to predictions from the Cold Dark Matter (CDM) model, making it challenging to distinguish between CDM and FDM solely through stellar observations., Comment: 13 pages, 8 figures, 6 tables. Paper submitted to MNRAS

We present the first steps toward applying causal representation learning to astronomy. Following up on previous work that introduced causal discovery to the field for the first time, here we solve a long standing conundrum by identifying the direction of the causal relation between supermassive black hole (SMBH) mass and their host galaxy properties. This leverages a score-based causal discovery approach with an exact posterior calculation. Causal relations between SMBHs and their host galaxies are further clarified by Independent Component Analysis (ICA). The astrophysical problem we focus on is one of the most important open issues in the field and one that has not seen a definitive resolution in decades. We consider the space of six physical properties of galaxies, subdivided by morphology: elliptical, lenticular, and spiral, plus SMBH mass. We calculate an exact posterior over the space of directed acyclic graphs for these variables based on a flat prior and the Bayesian Gaussian equivalent score. The nature of the causal relation between galaxy properties and SMBH mass is found to vary smoothly with morphology, with galaxy properties determining SMBH mass in ellipticals and vice versa in spirals. This settles a long-standing debate and is compatible with our theoretical understanding of galaxy evolution. ICA reveals a decreasing number of meaningful Independent Components (ICs) from ellipticals and lenticular to spiral. Moreover, we find that only one IC correlates with SMBH mass in spirals while multiple ones do in ellipticals, further confirming our finding that SMBH mass causes galaxy properties in spirals, but the reverse holds in ellipticals., Comment: Accepted by NeurIPS 2024 Causal Representation Learning Workshop. arXiv admin note: substantial text overlap with arXiv:2410.00965

Correlations between galaxies and their supermassive black holes (SMBHs) have been observed, but the causal mechanisms remained unclear. The emerging field of causal inference now enables examining these relationships using observational data. This study, using advanced causal discovery techniques and a state-of-the-art dataset, reveals a causal link between galaxy properties and SMBH masses. In elliptical galaxies, bulge properties influence SMBH growth, while in spiral galaxies, SMBHs affect host galaxy properties, potentially through feedback in gas-rich environments. For spiral galaxies, SMBHs progressively quench star formation, whereas in elliptical galaxies, quenching is complete, and the causal connection has reversed. These findings support theoretical models of active galactic nuclei feedback regulating galaxy evolution and suggest further exploration of causal links in astrophysical and cosmological scaling relations., Comment: 34 pages, 20 figures, submitted for peer-review

Intermediate Mass Black Hole (IMBH) mergers with masses $10^4 - 10^6$ $M_{\odot}$ are expected to produce gravitational waves (GWs) detectable by the Laser Interferometer Space Antenna (LISA) with high signal to noise ratios out to redshift 20. IMBH mergers are expected to take place within dwarf galaxies, however, the dynamics, timescales, and effect on their hosts are largely unexplored. In a previous study, we examined how IMBHs would pair and merge within nucleated dwarf galaxies. IMBHs in nucleated hosts evolve very efficiently, forming a binary system and coalescing within a few hundred million years. Although the fraction of dwarf galaxies ($10^7$ M$_{\odot} \leq$ $M_{\star} \leq 10^{10}$ M$_{\odot}$) hosting nuclear star clusters is between 60-100\%, this fraction drops to 20-70\% for lower-mass dwarfs ($M_{\star}\approx 10^7$ M$_{\odot}$), with the largest drop in low-density environments. Here, we extend our previous study by performing direct $N-$body simulations to explore the dynamics and evolution of IMBHs within non-nucleated dwarf galaxies, under the assumption that IMBHs exist within these dwarfs. To our surprise, none of IMBHs in our simulation suite merge within a Hubble time, despite many attaining high eccentricities $e \sim 0.7-0.95$. We conclude that extremely low stellar density environments in the centers of non-nucleated dwarfs do not provide an ample supply of stars to interact with IMBHs binary resulting in its stalling, in spite of triaxiality and high eccentricity, common means to drive a binary to coalescence. Our findings underline the importance of considering all detailed host properties to predict IMBH merger rates for LISA., Comment: Submitted to ApJ

Cosmological galaxy formation simulations are powerful tools to understand the complex processes that govern the formation and evolution of galaxies. However, evaluating the realism of these simulations remains a challenge. The two common approaches for evaluating galaxy simulations is either through scaling relations based on a few key physical galaxy properties, or through a set of pre-defined morphological parameters based on galaxy images. This paper proposes a novel image-based method for evaluating the quality of galaxy simulations using unsupervised deep learning anomaly detection techniques. By comparing full galaxy images, our approach can identify and quantify discrepancies between simulated and observed galaxies. As a demonstration, we apply this method to SDSS imaging and NIHAO simulations with different physics models, parameters, and resolution. We further compare the metric of our method to scaling relations as well as morphological parameters. We show that anomaly detection is able to capture similarities and differences between real and simulated objects that scaling relations and morphological parameters are unable to cover, thus indeed providing a new point of view to validate and calibrate cosmological simulations against observed data., Comment: 13 pages, 16 figures, published in MNRAS

We present the High-$z$ Evolution of Large and Luminous Objects (HELLO) project, a set of $\sim\!30$ high-resolution cosmological simulations aimed to study Milky Way analogues ($M_\star\sim10^{10-11}$\,\Msun) at high redshift ($z\sim [2-4]$). Based on the Numerical Investigation of a Hundred Astrophysical Objects (NIHAO), HELLO features an updated scheme for chemical enrichment and the addition of local photoionization feedback. Independently of redshift and mass, our galaxies exhibit a smooth progression along the star formation main sequence until $M_\star \sim\!10^{10.5}$, around which our sample at $z \sim 4$ remains mostly unperturbed while the most massive galaxies at $z \sim 2$ reach their peak star formation rate (SFR) and its subsequent decline, due to a mix of gas consumption and stellar feedback. While AGN feedback remains subdominant with respect to stellar feedback for energy deposition, its localised nature likely adds to the physical processes leading to declining SFRs. The phase in which a galaxy in our mass range can be found at a given redshift is set by its gas reservoir and assembly history. Finally, our galaxies are in excellent agreement with various scaling relations observed with the \textit{Hubble Space Telescope} and the \textit{James Webb Space Telescope}, and hence can be used to provide the theoretical framework to interpret current and future observations from these facilities and shed light on the transition from star-forming to quiescent galaxies., Comment: 21 pages, 15 figures, 3 tables, published in MNRAS

This paper presents a study of the impact of supermassive black hole (SMBH) feedback on dark matter (DM) halos in numerical NIHAO simulations of galaxies. In particular, the amount of DM displaced via active galactic nuclei (AGN) feedback and the physical scale over which AGN feedback affects the DM halo are quantified by comparing NIHAO simulations with and without AGN feedback. NIHAO galaxies with $\log(M_*/M_{\rm \odot})\geq 10.0$ show a growing central DM suppression of 0.2 dex (~40%) from z = 1.5 to the present relative to noAGN feedback simulations. The growth of the DM suppression is related to the mass evolution of the SMBH and the gas mass in the central regions. For the most massive NIHAO galaxies with $\log(M_*/M_{\rm \odot}) > 10.5$, partially affected by numerical resolution, the central DM suppression peaks at z = 0.5, after which halo contraction overpowers AGN feedback due a shortage of gas and, thus, SMBH growth. The spatial scale, or ``sphere of influence,'' over which AGN feedback affects the DM distribution decreases as a function of time for MW-mass galaxies (from ~16 kpc at z = 1.5 to ~7.8 kpc at z = 0) as a result of halo contraction due to stellar growth. For the most massive NIHAO galaxies, the size of the sphere of influence remains constant (~16 kpc) for z > 0.5 owing to the balance between AGN feedback and halo contraction., Comment: 14 pages, 13 figures, accepted for publication in MNRAS

It is well known that stars move away from their birth location over time via radial migration. This dynamical process makes computing the correct chemical evolution, e.g., metallicity gradients, of galaxies very difficult. This dynamical process makes inferring the chemical evolution of observed galaxies from their measured abundance gradients very difficult. One way to account for radial migration is to infer stellar birth radii for individual stars. Many attempts to do so have been performed over the last years, but are limited to the Milky Way as computing the birth position of stars requires precise measurements of stellar metallicity and age for individual stars that cover large Galactic radii. Fortunately, recent and future surveys will provide numerous opportunities for inferring birth radii for external galaxies such as the Large Magellanic Cloud (LMC). In this paper, we investigate the possibility of doing so using the NIHAO cosmological zoom-in simulations. We find that it is theoretically possible to infer birth radii with a ~ 25% median uncertainty for individual stars in galaxies with i) orderliness of the orbits, $\langle v_\phi \rangle/\sigma_{v} >$ 2, ii) a dark matter halo mass greater or equal to approximately the LMC mass (~ 2 x 10$^{11} M_\odot$), and iii) after the average azimuthal velocity of the stellar disk reaches ~70% of its maximum. From our analysis, we conclude that it is possible and useful to infer birth radii for the LMC and other external galaxies that satisfy the above criteria., Comment: 8 pages, 8 figures. Missing citations welcome

Firmamento (https://firmamento.hosting.nyu.edu) is a new-concept web-based and mobile-friendly data analysis tool dedicated to multi-frequency/multi-messenger emitters, as exemplified by blazars. Although initially intended to support a citizen researcher project at New York University-Abu Dhabi (NYUAD), Firmamento has evolved to be a valuable tool for professional researchers due to its broad accessibility to classical and contemporary multi-frequency open data sets. From this perspective Firmamento facilitates the identification of new blazars and other multi-frequency emitters in the localisation uncertainty regions of sources detected by current and planned observatories such as Fermi-LAT, Swift , eROSITA, CTA, ASTRI Mini-Array, LHAASO, IceCube, KM3Net, SWGO, etc. The multi-epoch and multi-wavelength data that Firmamento retrieves from over 90 remote and local catalogues and databases can be used to characterise the spectral energy distribution and the variability properties of cosmic sources as well as to constrain physical models. Firmamento distinguishes itself from other online platforms due to its high specialization, the use of machine learning and other methodologies to characterise the data and for its commitment to inclusivity. From this particular perspective, its objective is to assist both researchers and citizens interested in science, strengthening a trend that is bound to gain momentum in the coming years as data retrieval facilities improve in power and machine learning/artificial intelligence tools become more widely available, Comment: Accepted for publication in AJ

Fuzzy Dark Matter (FDM) has recently emerged as an interesting alternative model to the standard Cold Dark Matter (CDM). In this model, dark matter consists of very light bosonic particles with quantum mechanical effects on galactic scales. Using the N-body code AX-GADGET, we perform cosmological simulations of FDM that fully model the dynamical effects of the quantum potential throughout cosmic evolution. Through the combined analysis of FDM volume and high-resolution zoom-in simulations of different FDM particle masses ($m_{\chi}$ $\sim$ $10^{-23} - 10^{-21}$ eV/c$^2$), we study how FDM impacts the abundance of substructure and the inner density profiles of dark matter haloes. For the first time, using our FDM volume simulations, we provide a fitting formula for the FDM-to-CDM subhalo abundance ratio as a function of the FDM mass. More importantly, our simulations clearly demonstrate that there exists an extended FDM particle mass interval able to reproduce the observed substructure counts and, at the same time, create substantial cores ($r_{c} \sim 1$ kpc) in the density profile of dwarf galaxies ($\approx 10^{9}-10^{10}$ M$_{\odot}$), which stands in stark contrast with CDM predictions even with baryonic effects taken into account. The dark matter distribution in the faintest galaxies offers then a clear way to discriminate between FDM and CDM., Comment: 12 pages, 8 figures

Active Galactic Nuclei (AGN) in cosmological simulations generate explosive feedback that regulates star formation in massive galaxies, modifying the gas phase structure out to large distances. Here, we explore the direct effects that AGN radiation has on gas heating and cooling within one high-resolution $z=3$ dark matter halo as massive as a quasar host ($M_{\rm h}=$10$^{\rm 12.5}$M$_{\rm\odot}$), run without AGN feedback. We assume AGN radiation to impact the circumgalactic medium (CGM) anisotropically, within a bi-cone of angle $\alpha$. We find that even a relatively weak AGN (black hole mass $M_{\rm\bullet}=10^{\rm 8}$M$_{\rm\odot}$ with an Eddington ratio $\lambda=0.1$) can significantly lower the fraction of halo gas that is catastrophically cooling compared to the case of gas photoionized only by the ultraviolet background (UVB). Varying $M_{\rm\bullet}$, $\lambda$ and $\alpha$, we study their effects on observables. A 10$^{\rm 9}$M$_{\rm\odot}$ AGN with $\lambda=0.1$ and $\alpha\approxeq60^{^{\rm o}}$ reproduces the average surface brightness (SB) profiles of Ly$\alpha$, HeII and CIV, and results in a covering fraction of optically thick absorbers within observational estimates. The simulated SB$_{\rm CIV}$ profile is steeper than observed, indicating that not enough metals are pushed beyond the very inner CGM. For this combination of parameters, the CGM mass catastrophically cooling is reduced by half with respect to the UVB-only case, with roughly same mass out of hydrostatic equilibrium heating up and cooling down, hinting to the importance of self-regulation around AGNs. This study showcases how CGM observations can constrain not only the properties of the CGM itself, but also those of the AGN engine., Comment: accepted for publication in MNRAS

We utilize the public GIZMO code to simulate twelve disc galaxies from the NIHAO suite simulated with the GASOLINE code, then compare the corresponding galaxies in the two simulations. We find that while both codes with the same initial conditions and large-scale environments can successfully produce similar disc galaxies, significant differences are still seen in many properties of the galaxies, particularly in the circumgalactic medium (CGM) environment they reside. Specifically, the thermal feedback recipe used in GASOLINE results in ubiquitous long-lasting collimated outflows, primarily driven by high-density hot interstellar medium (ISM) from the galaxy center, and inflows of gas not aligned with the outflow cools rapidly and flows towards the galactic center. In contrast, galaxies from GIZMO code do not exhibit large-scale outflows at low redshifts, but instead display quasi-virialized hot gaseous halos that arise from the strong interaction between inflow of gas and feedback driven outflow. Therefore, the origins of mass and angular momentum of the cold disc in the two simulations are quite different, even though the final morphologies of corresponding galaxies are similar at $z\sim0$. The differences in the distribution of CGM gas are mainly due to different feedback models implemented in the two codes, thus future observations of CGM provide valuable insight into the physics governing the baryon cycle in disc galaxies., Comment: 17 pages, 11 figures, Submitted to ApJ, Comments welcome

Previous studies have revealed that the estimated probability of galaxy-galaxy strong lensing in observed galaxy clusters exceeds the expectations from the $\Lambda$ Cold Dark Matter cosmological model by one order of magnitude. We aim to understand the origin of this excess by analyzing a larger set of simulated galaxy clusters and investigating how the theoretical expectations vary under different adopted prescriptions and numerical implementations of star formation and feedback in simulations. We perform a ray-tracing analysis of 324 galaxy clusters from the Three Hundred project, comparing the Gadget-X and Gizmo-Simba runs. These simulations, which start from the same initial conditions, are performed with different implementations of hydrodynamics and galaxy formation models tailored to match different observational properties of the Intra-Cluster-Medium and cluster galaxies. We find that galaxies in the Gizmo-Simba simulations develop denser stellar cores than their Gadget-X counterparts. Consequently, their probability for galaxy-galaxy strong lensing is higher by a factor of $\sim 3$. This increment is still insufficient to fill the gap with observations, as a discrepancy by a factor $\sim 4$ still persists. In addition, we find that several simulated galaxies have Einstein radii that are too large compared to observations. We conclude that a persistent excess of galaxy-galaxy strong lensing exists in observed galaxy clusters. The origin of this discrepancy with theoretical predictions is still unexplained in the framework of the cosmological hydrodynamical simulations. This might signal a hitherto unknown issue with either the simulation methods or our assumptions regarding the standard cosmological model., Comment: 6 pages, 2 figures, accepted for publication on A&A Letters. See companion paper Srivastava et al. (2023)

This article presents an open-source architecture for conveying robots' intentions to human teammates using Mixed Reality and Head-Mounted Displays. The architecture has been developed focusing on its modularity and re-usability aspects. Both binaries and source code are available, enabling researchers and companies to adopt the proposed architecture as a standalone solution or to integrate it in more comprehensive implementations. Due to its scalability, the proposed architecture can be easily employed to develop shared Mixed Reality experiences involving multiple robots and human teammates in complex collaborative scenarios., Comment: 6 pages, 3 figures, accepted for publication in the proceedings of the 32nd IEEE International Conference on Robot and Human Interactive Communication (RO-MAN)

We append two additional black hole (BH) accretion models, namely viscous disc and gravitational torque-driven accretion, into the Numerical Investigation of a Hundred Astrophysical Objects (NIHAO) project of galaxy simulations. We show that these accretion models, characterized by a weaker dependence on the BH mass compared to the commonly used Bondi-Hoyle accretion, naturally create a common evolutionary track (co-existence) between the mass of the BH and the stellar mass of the galaxy, even without any direct coupling via feedback (FB). While FB is indeed required to control the final BH and stellar mass of the galaxies, our results suggest that FB might not be the leading driver of the cosmic co-evolution between these two quantities; in these models, co-evolution is simply determined by the shared central gas supply. Conversely, simulations using Bondi-Hoyle accretion show a two-step evolution, with an early growth of stellar mass followed by exponential growth of the central supermassive black hole (SMBH). Our results show that the modelling of BH accretion (sometimes overlooked) is an extremely important part of BH evolution and can improve our understanding of how scaling relations emerge and evolve, and whether SMBH and stellar mass co-exist or co-evolve through cosmic time., Comment: 13 pages, 10 figures

Recent observations of the Milky Way (MW) found an unexpected steepening of the star-forming gas metallicity gradient around the time of the Gaia-Sausage-Enceladus (GSE) merger event. Here we investigate the influence of early ($t_{\mathrm{merger}}\lesssim5$ Gyr) massive ($M_{\mathrm{gas}}^{\mathrm{merger}}/M_{\mathrm{gas}}^{\mathrm{main}}(t_{\mathrm{merger}})\gtrsim10\%$) merger events such as the Gaia-Sausage Enceladus merger in the MW on the evolution of the cold gas metallicity gradient. We use the NIHAO-UHD suite of cosmological hydrodynamical simulations of MW-mass galaxies to study the frequency of massive early mergers and their detailed impact on the morphology and chemistry of the gaseous disks. We find a strong steepening of the metallicity gradient at early times for all four galaxies in our sample which is caused by a sudden increase in the cold gas disk size (up to a factor of 2) in combination with the supply of un-enriched gas ($\sim0.75$ dex lower compared to the main galaxy) by the merging dwarf galaxies. The mergers mostly affect the galaxy outskirts and lead to an increase in cold gas surface density of up to 200% outside of $\sim8$ kpc. The addition of un-enriched gas breaks the self-similar enrichment of the inter-stellar-medium and causes a dilution of the cold gas in the outskirts of the galaxies. The accreted stars and the ones formed later out of the accreted gas inhabit distinct tracks offset to lower [$\alpha$/Fe] and [Fe/H] values compared to the main galaxy's stars. We find that such mergers can contribute significantly to the formation of a second, low-$\alpha$ sequence as is observed in the MW., Comment: 13 pages, 10 figures, accepted by MNRAS

We present simulated galaxy spectral energy distributions (SEDs) from the far ultraviolet through the far infrared, created using hydrodynamic simulations and radiative transfer calculations, suitable for the validation of SED modeling techniques. SED modeling is an essential tool for inferring star formation histories from nearby galaxy observations, but is fraught with difficulty due to our incomplete understanding of stellar populations, chemical enrichment processes, and the non-linear, geometry dependent effects of dust on our observations. Our simulated SEDs will allow us to assess the accuracy of these inferences against galaxies with known ground truth. To create the SEDs, we use simulated galaxies from the NIHAO suite and the radiative transfer code SKIRT. We explore different sub-grid post-processing recipes, using color distributions and their dependence on axis ratio of galaxies in the nearby universe to tune and validate them. We find that sub-grid post-processing recipes that mitigate limitations in the temporal and spatial resolution of the simulations are required for producing FUV to FIR photometry that statistically reproduce the colors of galaxies in the nearby universe. With this paper we release resolved photometry and spatially integrated spectra for our sample galaxies, each from a range of different viewing angles. Our simulations predict that there is a large variation in attenuation laws among galaxies, and that from any particular viewing angle that energy balance between dust attenuation and reemission can be violated by up to a factor of 3. These features are likely to affect SED modeling accuracy.

We present a catalogue of dynamical properties for 2368 late-type galaxies from the MaNGA survey. The latter complements the catalogue of photometric properties for the same sample based on deep optical DESI photometry processed with AutoProf. Rotation curves (RCs), extracted by model fitting H$\alpha$ velocity maps from the MaNGA Data Analysis Pipeline, extend out to 1.4 (1.9) R$_{e}$ for the primary (secondary) MaNGA samples. The RCs and ancillary MaNGA Pipe3D data products were used to construct various fundamental galaxy scaling relations that are also compared uniformly with similar relations from NIHAO zoom-in simulations. Simulated NIHAO galaxies were found to broadly reproduce the observed MaNGA galaxy population for $\log (M_*/{\rm M_{\odot}) > 8.5}$. Some discrepancies remain, such as those pertaining to central stellar densities and the diversity of RCs due to strong feedback schemes. Also presented are spatially-resolved scatters for the velocity-size-stellar mass (VRM$_*$) structural relations using MaNGA and NIHAO samples. The scatter for these relations in the galaxian interiors is a consequence of the diversity of inner RC shapes, while scatter in the outskirts is dictated by the large range of stellar surface densities which itself is driven by sporadic star formation. The detailed spatially-resolved scatter analysis highlights the complex interplay between local and global astrophysical processes and provides a strong constraint to numerical simulations., Comment: 21 pages, 13 Figures, Accepted for publication in MNRAS

We present the first high-resolution zoom-in simulation of a Milky-way-like halo extracted from the Aquarius Project in the Fuzzy Dark Matter (FDM) framework. We use the N-body code AX-GADGET, based on a particle oriented solution of the Schr\"{o}dinger-Poisson equations, able to detail the complexity of structure formation while keeping track of the quantum effects in FDM. The halo shows a cored density profile, with a core size of several kpc for a FDM mass of $m_{\chi}=2.5h \times 10^{-22}\ {\rm eV}/c^2$. A flattening is observed also in the velocity profile, representing a distinct feature of FDM dynamics. We provide a quantitative analysis of the impact of fuzziness on satellites in terms of abundance, mass, distance and velocity distribution functions and their evolution with redshift. Very interestingly, we show that all collapsed structures, despite showing a flat density profile at $z=0$, do not reach the solitonic ground-state at the time of formation: on the contrary, they asymptotically converge to it on a timescale that depends on their mass and formation history. This implies that current limits on FDM mass - obtained by applying simple scaling relations to observed galaxies - should be taken with extreme care, since single objects can significantly deviate from the expected asymptotic behavior during their evolution., Comment: 14 pages, 9 figures. Submitted to MNRAS

Numerical simulations within a cold dark matter (DM) cosmology form halos whose density profiles have a steep inner slope (`cusp'), yet observations of galaxies often point towards a flat central `core'. We develop a convolutional mixture density neural network model to derive a probability density function (PDF) of the inner density slopes of DM halos. We train the network on simulated dwarf galaxies from the NIHAO and AURIGA projects, which include both DM cusps and cores: line-of-sight velocities and 2D spatial distributions of their stars are used as inputs to obtain a PDF representing the probability of predicting a specific inner slope. The model recovers accurately the expected DM profiles: $\sim$82$\%$ of the galaxies have a derived inner slope within $\pm$0.1 of their true value, while $\sim$98$\%$ within $\pm$0.3. We apply our model to four Local Group dwarf spheroidal galaxies and find results consistent with those obtained with the Jeans modelling based code GravSphere: the Fornax dSph has a strong indication of possessing a central DM core, Carina and Sextans have cusps (although the latter with large uncertainties), while Sculptor shows a double peaked PDF indicating that a cusp is preferred, but a core can not be ruled out. Our results show that simulation-based inference with neural networks provide a innovative and complementary method for the determination of the inner matter density profiles in galaxies, which in turn can help constrain the properties of the elusive DM., Comment: 14 pages, 11 figures, submitted to MNRAS. comments welcome

Close human-robot interaction (HRI), especially in industrial scenarios, has been vastly investigated for the advantages of combining human and robot skills. For an effective HRI, the validity of currently available human-machine communication media or tools should be questioned, and new communication modalities should be explored. This article proposes a modular architecture allowing human operators to interact with robots through different modalities. In particular, we implemented the architecture to handle gestural and touchscreen input, respectively, using a smartwatch and a tablet. Finally, we performed a comparative user experience study between these two modalities., Comment: Accepted for publication at the 17th International Conference on Intelligent Autonomous Systems (IAS-17)

Humans engaged in collaborative activities are naturally able to convey their intentions to teammates through multi-modal communication, which is made up of explicit and implicit cues. Similarly, a more natural form of human-robot collaboration may be achieved by enabling robots to convey their intentions to human teammates via multiple communication channels. In this paper, we postulate that a better communication may take place should collaborative robots be able to anticipate their movements to human teammates in an intuitive way. In order to support such a claim, we propose a robot system's architecture through which robots can communicate planned motions to human teammates leveraging a Mixed Reality interface powered by modern head-mounted displays. Specifically, the robot's hologram, which is superimposed to the real robot in the human teammate's point of view, shows the robot's future movements, allowing the human to understand them in advance, and possibly react to them in an appropriate way. We conduct a preliminary user study to evaluate the effectiveness of the proposed anticipatory visualization during a complex collaborative task. The experimental results suggest that an improved and more natural collaboration can be achieved by employing this anticipatory communication mode.

We have analysed two cosmological zoom simulations with $M_{\rm vir}\sim 10^{12}{\rm\,M}_\odot$ from the NIHAO series, both with and without feedback. We show that an entropy criterion based on the equation of state of the intergalactic medium can successfully separate cold- and hot-mode accretion. The shock-heated gas has non-negligible turbulent support and cools inefficiently. In the simulations without feedback, only a small fraction ($\sim 20$ per cent) of the stellar mass comes from baryons that have been in the hot circumgalactic medium, although quantitative conclusions should be taken with caution due to our small-number statistics. With feedback, the fraction is larger because of the reaccretion of gas heated by supernovae, which has lower entropies and shorter cooling times than the gas heated by accretion shocks. We have compared the results of NIHAO to predictions of the GalICS 2.1 semianalytic model of galaxy formation. The shock-stability criterion implemented in GalICS 2.1 successfully reproduces the transition from cold- to hot-mode accretion., Comment: 23 pages, 16 figures, Accepted for publication in MNRAS

Supernovae feedback driven expansion has proven to be a viable mechanism to explain the average properties of Ultra Diffuse Galaxies (UDGs) such as the sizes, colors, mass and internal kinematics. Here, we explore the origin of stellar metallicity gradients in feedback driven simulated UDGs from the NIHAO project and compare them with the observed distribution of metallicity gradients of both Local Group dwarfs as well as of the recently observed UDG DF44. Simulated UDGs display a large variety of metallicity profiles, showing flat to negative gradients, similarly to what is observed in LG dwarfs, while DF44 data suggest a flat to positive gradient. The variety of metallicity gradients in simulations is set by the interplay between the radius at which star formation occurs and the subsequent supernovae feedback driven stellar redistribution: rotation supported systems tend to have flat metallicity profiles while dispersion supported galaxies show negative and steep profiles. Our results suggest that UDGs are not peculiar in what regards their metallicity gradients, when compared to regular dwarfs. Desirably, a larger observational sample of UDGs' gradients shall be available in the future, in order to test our predictions., Comment: 13 pages, 6+3 figures

Although active galactic nuclei (AGN) feedback is required in simulations of galaxies to regulate star formation, further downstream effects on the dark matter distribution of the halo and stellar kinematics of the central galaxy can be expected. We combine simulations of galaxies with and without AGN physics from the Numerical Investigation of a Hundred Astrophysical Objects (NIHAO) to investigate the effect of AGN on the dark matter profile and central stellar rotation of the host galaxies. Specifically, we study how the concentration-halo mass ($c-M$) relation and the stellar spin parameter ($\lambda_R$) are affected by AGN feedback. We find that AGN physics is crucial to reduce the central density of simulated massive ($\gtrsim 10^{12}$ M$_\odot$) galaxies and bring their concentration to agreement with results from the Spitzer Photometry & Accurate Rotation Curves (SPARC) sample. Similarly, AGN feedback has a key role in reproducing the dichotomy between slow and fast rotators as observed by the ATLAS$^{3\text{D}}$ survey. Without star formation suppression due to AGN feedback, the number of fast rotators strongly exceeds the observational constraints. Our study shows that there are several collateral effects that support the importance of AGN feedback in galaxy formation, and these effects can be used to constrain its implementation in numerical simulations., Comment: Accepted for publication in MNRAS. 15 pages, 10 figures

The transition of high-mass galaxies from being blue and star forming to being red and dead is a crucial step in galaxy evolution, yet not fully understood. In this work, we use the NIHAO suite of galaxy simulations to investigate the relation between the transition time through the green valley and other galaxy properties. The typical green valley crossing time of our galaxies is approximately 400 Myr, somewhat shorter than observational estimates. The crossing of the green valley is triggered by the onset of AGN feedback and the subsequent shut down of star formation. Interestingly the time spent in the green valley is not related to any other galaxy properties, such as stellar age or metallicity, or the time at which the star formation quenching takes place. The crossing time is set by two main contributions: the ageing of the current stellar population and the residual star formation in the green valley. These effects are of comparable magnitude, while major and minor mergers have a negligible contribution. Most interestingly, we find the time that a galaxy spends to travel through the green valley is twice the $e$-folding time of the star formation quenching. This result is stable against galaxy properties and the exact numerical implementation of AGN feedback in the simulation. Assuming a typical crossing time of about one Gyr inferred from observations, our results imply that any mechanism or process aiming to quench star formation, must do it on a typical timescale of 500 Myr., Comment: Accepted by MNRAS

An extensive catalog of spatially-resolved galaxy rotation curves and multi-band optical light profiles for 1752 observed spiral galaxies is assembled to explore the drivers of diversity in galaxy structural parameters, rotation curve shapes, and stellar mass profiles. Similar data were extracted from the NIHAO galaxy simulations to identify any differences between observations and simulations. Several parameters, including the inner slope "S" of a rotation curve (RC), were tested for diversity. Two distinct populations are found in observed and simulated galaxies; (i) blue, low mass spirals with stellar mass M* < 10^9.3 Msol and roughly constant "S", and (ii) redder, more massive and more diverse spirals with rapidly increasing "S". In all cases, the value of "S" seems equally contributed by the baryonic and non-baryonic (dark) matter. Diversity is shown to increase mildly with mass. Numerical simulations reproduce well most baryon-dominated galaxy parameter distributions, such as the inner stellar mass profile slope and baryonic scaling relations, but they struggle to match the full diversity of observed galaxy rotation curves (through "S") and most dark-matter-dominated parameters. To reproduce observations, the error broadening of the simulation's intrinsic spread of RC metrics would have to be tripled. The differences in various projections of observed and simulated scaling relations may reflect limitations of current sub-grid physics models to fully capture the complex nature of galaxies. For instance, AGNs are shown to have a significant effect on the shapes of simulated RCs. The inclusion of AGN feedback brings simulated and observed inner RC shapes into closer agreement., Comment: 22 pages, 14 figures, submitted to MNRAS, comments welcome

Cosmological galaxy formation simulations are still limited by their spatial/mass resolution and cannot model from first principles some of the processes, like star formation, that are key in driving galaxy evolution. As a consequence they still rely on a set of 'effective parameters' that try to capture the scales and the physical processes that cannot be directly resolved in the simulation. In this study we show that it is possible to use Machine Learning techniques applied to real and simulated images of galaxies to discriminate between different values of these parameters by making use of the full information content of an astronomical image instead of collapsing it into a limited set of values like size, or stellar/ gas masses. In this work we apply our method to the NIHAO simulations and the THINGS and VLA-ANGST observations of HI maps in nearby galaxies to test the ability of different values of the star formation density threshold $n$ to reproduce observed HI maps. We show that observations indicate the need for a high value of $n \gtrsim 80$ ,cm$^{-3}$ (although the exact numerical value is model-dependent), which has important consequences for the dark matter distribution in galaxies. Our study shows that with innovative methods it is possible to take full advantage of the information content of galaxy images and compare simulations and observations in an interpretable, non-parametric and quantitative manner., Comment: 8 pages, 5 figures, accepted for publication on MNRAS

The spin, $\lambda$, of dark matter (DM) halos in cosmological simulations follows a log normal distribution and has little correlation with galaxy observables. As such, there is currently no way to infer the $\lambda$ parameter of individual halos hosting observed galaxies. We present here a first attempt to measure $\lambda$ starting from the dynamically distinct stellar components identified in high-resolution cosmological simulations with Galactic Structure Finder. In a subsample of NIHAO galaxies, we find tight correlations between the total angular momentum (AM) of the DM halos, $J_h$, and the azimuthal AM, $J_z$, of the stellar components of the form: log($J_h$)=$\alpha$+$\beta\cdot$log($J_z$). The stellar halos have the tightest relation with $\alpha=9.50\pm0.42$ and $\beta=0.46\pm0.04$. The other tight relation is with the disks: $\alpha=6.15\pm0.92$ and $\beta=0.68\pm0.07$. We used Gaia DR2 and APOGEE to generate a combined kinematics-abundance space, where the Galaxy's thin and thick stellar disks stars can be neatly separated and their rotational velocity profiles, $v_{\phi}(R)$, can be computed. For both disks, $v_{\phi}(R)$ decreases with radius with $\sim$2 km s$^{-1}$ kpc$^{-1}$ for $R\gtrsim5$ kpc, resulting in $v_{\phi,thin}\backsimeq221$ km s$^{-1}$ and $v_{\phi,thick}\backsimeq188$ km s$^{-1}$ at $R_{\odot}$. These velocity profiles together with the Galaxy mass model of Cautun et al. (2020) result in the AM for the two disks: $J_{z,thin}=(3.26\pm0.43)\times10^{13}$ and $J_{z,thick}=(1.20\pm0.30)\times10^{13}$ M$_{\odot}$ kpc km s$^{-1}$, where the DM halo is assumed to have a contracted NFW profile. Adopting the correlation found in simulations, the spin estimate of the Galaxy's DM halo is $\lambda_{MW}=0.061^{+0.022}_{-0.016}$. If the DM halo has a NFW profile instead, the spin becomes $\lambda_{MW}=0.088^{+0.024}_{-0.020}$, making the Galaxy a more extreme outlier., Comment: 15 pages, 7 figures, accepted for publication in A&A

Recent observational and theoretical studies of the Local Group (LG) dwarf galaxies have highlighted their unique star-formation history, stellar metallicity, gas content, and kinematics. We investigate the commonality of these features by comparing constrained LG and field central dwarf halo simulations in the Numerical Investigation of a Hundred Astrophysical Objects (NIHAO) project. Our simulations, performed with NIHAO-like hydrodynamics which track the evolution of the Milky Way (MW) and M31 along with ~100 dwarfs in the LG, reveal the total gas mass and stellar properties (velocity dispersion, evolution history, etc.) of present-day LG dwarfs to be similar to field systems. However, relative to field galaxies, LG dwarfs have more cold gas in their central parts and more metal-rich gas in the halo stemming from interactions with other dwarfs living in a high-density environment like the LG. Interestingly, the direct impact of massive MW/M31 analogues on the metallicity evolution of LG dwarfs is minimal; LG dwarfs accrete high-metallicity gas mostly from other dwarfs at late times. We have also tested for the impact of metal diffusion on the chemical evolution of LG dwarfs, and found that it does not affect the stellar or gaseous content of LG dwarfs. Our simulations suggest that the stellar components of LG dwarfs offer a unique and unbiased local laboratory for galaxy-formation tests and comparisons, especially against the overall dwarf population in the Universe., Comment: 16 pages, 12 figures, Accepted for publication in MNRAS

A central question regarding Ultra Diffuse Galaxies (UDGs) is whether they are a separate category to Low Surface Brightness (LSB) galaxies, or just their natural continuation towards low stellar masses. In this letter, we show that the rotation curve of the gas rich UDG AGC 242019 is well fit by a dark matter halo with inner slope that asymptotes to -0.54, and that such fit provides a concentration parameter that matches theoretical expectations. This finding, together with previously works in which shallow inner profiles are derived for UDGs, shows that the structural properties of these galaxies are like other observed LSBs. UDGs show slowly rising rotation curves and this favours formation scenarios in which internal processes, such as SNae driven gas outflows, are acting to modify UDGs profiles., Comment: Accepted for publication in ApJL