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A significant fraction of local galaxies exhibit stellar bars, non-axisymmetric structures composed of stars, gas, and dust. Identifying key differences between the properties of barred and unbarred galaxies can uncover clues about the conditions for triggering bar formation. We explore the early stages of bar formation in a small sample of disc barred galaxies extracted from the TNG50 cosmological simulation, and compare their properties to those of unbarred galaxies. According to our results, the most important difference between barred and unbarred galaxies is that the former have systematically higher fractions of stellar to dark matter mass in their inner regions, from very early stages and prior to the formation of the bars. They harbour high initial gas content, fostering increased star formation rates and leading to a central mass concentration that grows faster over time compared to unbarred galaxies. Examining the evolution of the halo spin within |$10\, \mathrm{ckpc}$| reveals that barred galaxies have higher angular momentum transfer from the disc to the halo. Curiously, both barred and unbarred galaxies share similar initial low values of the halo spin, consistent with those proposed in the literature for bar formation. Furthermore, we evaluate existing stability criteria to capture the complexity of the process, and investigate the effects of mergers, flybys, and environment as possible drivers of bar formation. We find no clear link between mergers and disc instabilities resulting in the formation of bars, even though some of the simulated barred galaxies might have been influenced by these events. [ABSTRACT FROM AUTHOR]

Measurements of the luminosity function of active galactic nuclei (AGN) at high redshift (z ≳ 6) are expected to suffer from field-to-field variance, including cosmic and Poisson variances. Future surveys, such as those from the Euclid telescope and JWST, will also be affected by field variance. We use the Uchuu simulation, a state-of-the-art cosmological N -body simulation with 2.1 trillion particles in a volume of 25.7 Gpc3, combined with a semi-analytic galaxy and AGN formation model, to generate the Uchuu–ν2GC catalogue, publicly available, that allows us to investigate the field-to-field variance of the luminosity function of AGN. With this Uchuu–ν2GC model, we quantify the cosmic variance as a function of survey area, AGN luminosity, and redshift. In general, cosmic variance decreases with increasing survey area and decreasing redshift. We find that at z ∼ 6 − 7, the cosmic variance depends weakly on AGN luminosity. This is because the typical mass of dark matter haloes in which AGN reside does not significantly depend on luminosity. Due to the rarity of AGN, Poisson variance dominates the total field-to-field variance, especially for bright AGN. We also examine the effect of parameters related to galaxy formation physics on the field variance. We discuss uncertainties present in the estimation of the faint-end of the AGN luminosity function from recent observations, and extend this to make predictions for the expected number of AGN and their variance for upcoming observations with Euclid , JWST, and the Legacy Survey of Space and Time (LSST). [ABSTRACT FROM AUTHOR]

We study the population of backsplash galaxies at z  = 0 in the outskirts of massive, isolated clusters of galaxies taken from the mdpl 2- sag semi-analytical catalogue. We consider four types of backsplash galaxies according to whether they are forming stars or passive at three stages in their lifetimes: before entering the cluster, during their first incursion through the cluster, and after they exit the cluster. We analyse several geometric, dynamic, and astrophysical aspects of the four types at the three stages. Galaxies that form stars at all stages account for the majority of the backsplash population (58 per cent) and have stellar masses typically below |$M_\star \sim 3\times 10^{10} \ h^{-1}\, {\rm {M_\odot }}$| that avoid the innermost cluster's regions and are only mildly affected by it. In a similar mass range, galaxies that become passive after exiting the cluster (26 per cent) follow orbits characterized by small pericentric distance and a strong deflection by the cluster potential well while suffering a strong loss of both dark matter and gas content. Only a small fraction of our sample (4 per cent) becomes passive while orbiting inside the cluster. These galaxies have experienced heavy pre-processing and the cluster's tidal stripping and ram pressure provide the final blow to their star formation. Finally, galaxies that are passive before entering the cluster for the first time (12 per cent) are typically massive and are not affected significantly by the cluster. Using the bulge/total mass ratio as a proxy for morphology, we find that a single incursion through a cluster does not result in significant morphological changes in all four types. [ABSTRACT FROM AUTHOR]

In this work, we combine the semi-analytic model of galaxy formation and evolution sag  with the 102 relaxed simulated galaxy clusters from the three hundred project, and we study the link between the quenching of star formation (SF) and the physical processes that galaxies experience through their dynamical history in and around clusters. We classify galaxies in four populations based on their orbital history: recent and ancient infallers, and backsplash and neighbouring galaxies. We find that ∼85 per cent of the current population of quenched galaxies located inside the clusters are ancient infallers with low or null content of hot and cold gas. The fraction of quenched ancient infallers increases strongly between the first and second pericentric passage, due to the removal of hot gas by the action of ram-pressure stripping (RPS). The majority of them quenches after the first pericentric passage, but a non-negligible fraction needs a second passage, specially galaxies with |$M_\star \le 10^{10.5} \, {\rm M_\odot }$|⁠. Recent infallers represent ∼15 per cent of the quenched galaxies located inside the cluster and, on average, they contain a high proportion of hot and cold gas; moreover, pre-processing effects are responsible for quenching the recent infallers prior to infall onto the main cluster progenitor. The ∼65 per cent of quenched galaxies located around clusters are backsplash galaxies, for which the combination of RPS acting during a pre-processing stage and inside the cluster is necessary for the suppression of SF in this population. [ABSTRACT FROM AUTHOR]

In this work, we investigate the structural properties, distribution and abundance of ΛCDM dark matter subhaloes using the Phi-4096 and Uchuu suite of N-body cosmological simulations. Thanks to the combination of their large volume, high mass resolution and superb statistics, we are able to quantify – for the first time consistently over more than seven decades in ratio of subhalo-to-host-halo mass – dependencies of subhalo properties on mass, maximum circular velocity, V max, host halo mass, and distance to host halo centre. We also dissect the evolution of these dependencies over cosmic time. We provide accurate fits for the subhalo mass and velocity functions, both exhibiting decreasing power-law slopes and with no significant dependence on redshift. We also find subhalo abundance to depend weakly on host halo mass. Subhalo structural properties are codified via a concentration parameter, c V, that does not depend on any pre-defined density profile and relies only on V max. We derive the c V− V max relation and find an important dependence on distance of the subhalo to the host halo centre. Interestingly, we also find subhaloes of the same mass to be significantly more concentrated when they reside inside more massive hosts. Finally, we investigate the redshift evolution of c V, and provide accurate fits. Our results offer an unprecedented detailed characterization of the subhalo population, consistent over a wide range of subhalo and host halo masses, as well as cosmic times. Thus, we expect our work to be particularly useful for any future research involving dark matter halo substructure. [ABSTRACT FROM AUTHOR]

We connect galaxy properties with their orbital classification by analysing a sample of galaxies with stellar mass M ⋆ ≥ 108.5 h −1M⊙ residing in and around massive and isolated galaxy clusters with mass M 200 > 1015 h −1M⊙ at redshift z  = 0. The galaxy population is generated by applying the semi-analytic model of galaxy formation sag  on the cosmological simulation MultiDark Planck 2. We classify galaxies considering their real orbits (3D) and their projected phase-space position using the roger   code (2D). We define five categories: cluster galaxies, galaxies that have recently fallen into a cluster, backsplash galaxies, infalling galaxies, and interloper galaxies. For each class, we analyse the 0.1(g − r) colour, the specific star formation rate (sSFR), and the stellar age, as a function of the stellar mass. For the 3D classes, we find that cluster galaxies have the lowest sSFR, and are the reddest and the oldest, as expected from environmental effects. Backsplash galaxies have properties intermediate between the cluster and recent infaller galaxies. For each 2D class, we find an important contamination by other classes. We find it necessary to separate the galaxy populations in red and blue to perform a more realistic analysis of the 2D data. For the red population, the 2D results are in good agreement with the 3D predictions. Nevertheless, when the blue population is considered, the 2D analysis only provides reliable results for recent infallers, infalling galaxies and interloper galaxies. [ABSTRACT FROM AUTHOR]

We present a model to track the orbital evolution of 'unresolved subhaloes' (USHs) in cosmological simulations. USHs are subhaloes that are no longer distinguished by halo finders as self-bound overdensities within their larger host system due to limited mass resolution. These subhaloes would host 'orphan galaxies' in semi-analytic models of galaxy formation and evolution (SAMs). Predicting the evolution of the phase-space components of USHs is crucial for the adequate modelling of environmental processes, interactions, and mergers implemented in SAMs that affect the baryonic properties of orphan satellites. Our model takes into account dynamical friction drag, mass-loss by tidal stripping and merger with the host halo, involving three free parameters. To calibrate this model, we consider two DM-only simulations of different mass resolution (MultiDark simulations). The simulation with higher mass resolution (smdpl ; |$m_{\rm DM} = 9.6 \times 10^7\, h^{-1}\, \mathrm{M_{\odot }}$|⁠) provides information about subhaloes that are not resolved in the lower mass resolution one (mdpl2 ; |$m_{\rm DM} = 1.5 \times 10^9\, h^{-1}\, \mathrm{M_{\odot }}$|⁠); the orbit of those USHs is tracked by our model. We use as constraining functions the subhalo mass function (SHMF) and the two-point correlation function (2PCF) obtained from smdpl , being the latter a novel aspect of our approach. While the SHMF fails to put tight constraints on the efficiency of dynamical friction and the merger condition, the addition of clustering information helps us to specify the parameters of the model related to the spatial distribution of subhaloes. Our model allows to achieve good convergence between the results of simulations of different mass resolution, with a precision better than 10 per cent for both SHMF and 2PCF. [ABSTRACT FROM AUTHOR]

We present a new analytic fitting profile to model the ram pressure (RP) exerted over satellite galaxies on different environments and epochs. The profile is built using the information of the gas particle distribution in hydrodynamical simulations of groups and clusters of galaxies to measure the RP directly. We show that predictions obtained by a previously introduced β -profile model cannot consistently reproduce the dependence of the RP on halocentric distance and redshift for a given halo mass. It features a systematic underestimation of the predicted RP at high redshifts (z > 1.5), which increases towards the central regions of the haloes and it is independent of halo mass, reaching differences larger than two decades for satellites at r < 0.4 R vir. This behaviour reverses as redshift decreases, featuring an increasing overestimation with halocentric distance at z  = 0. As an alternative, we introduce a new universal analytic model for the profiles that can recover the RP dependence on halo mass, halocentric distance, and redshift. We analyse the impact of our new profile on galaxy properties by applying a semi-analytic model of galaxy formation and evolution on top of the simulations. We show that galaxies experiencing large amounts of cumulative RP stripping typically have low stellar masses (M ⋆ ≤ 109.5 M⊙). Besides, their specific star formation histories depend on the RP modelling applied, particularly at high redshifts (z > 1.5). [ABSTRACT FROM AUTHOR]

We introduce the Uchuu suite of large high-resolution cosmological N -body simulations. The largest simulation, named Uchuu, consists of 2.1 trillion (12 8003) dark matter particles in a box of side-length 2.0 |$\, h^{-1} \, \rm Gpc$|⁠ , with particle mass of 3.27 × 108 |$\, h^{-1}\, \rm M_{\odot }$|⁠. The highest resolution simulation, Shin-Uchuu, consists of 262 billion (64003) particles in a box of side-length 140 |$\, h^{-1} \, \rm Mpc$|⁠ , with particle mass of 8.97 × 105 |$\, h^{-1}\, \rm M_{\odot }$|⁠. Combining these simulations, we can follow the evolution of dark matter haloes and subhaloes spanning those hosting dwarf galaxies to massive galaxy clusters across an unprecedented volume. In this first paper, we present basic statistics, dark matter power spectra, and the halo and subhalo mass functions, which demonstrate the wide dynamic range and superb statistics of the Uchuu suite. From an analysis of the evolution of the power spectra, we conclude that our simulations remain accurate from the baryon acoustic oscillation scale down to the very small. We also provide parameters of a mass–concentration model, which describes the evolution of halo concentration and reproduces our simulation data to within 5 per cent for haloes with masses spanning nearly eight orders of magnitude at redshift 0 ≤ z ≤ 14. There is an upturn in the mass–concentration relation for the population of all haloes and of relaxed haloes at z ≳ 0.5, whereas no upturn is detected at z < 0.5. We make publicly available various N -body products as part of Uchuu Data Release 1 on the Skies & Universes site. 1 Future releases will include gravitational lensing maps and mock galaxy, X-ray cluster, and active galactic nucleus catalogues. [ABSTRACT FROM AUTHOR]

We present the ROGER (Reconstructing Orbits of Galaxies in Extreme Regions) code, which uses three different machine learning techniques to classify galaxies in, and around, clusters, according to their projected phase-space position. We use a sample of 34 massive, M 200 > 1015 h −1 M ⊙, galaxy clusters in the MultiDark Planck 2 (MDLP2) simulation at redshift zero. We select all galaxies with stellar mass M ⋆ ≥ 108.5 h −1 M ⊙, as computed by the semi-analytic model of galaxy formation SAG, that are located in, and in the vicinity of, these clusters and classify them according to their orbits. We train ROGER to retrieve the original classification of the galaxies from their projected phase-space positions. For each galaxy, ROGER gives as output the probability of being a cluster galaxy, a galaxy that has recently fallen into a cluster, a backsplash galaxy, an infalling galaxy, or an interloper. We discuss the performance of the machine learning methods and potential uses of our code. Among the different methods explored, we find the K-Nearest Neighbours algorithm achieves the best performance. [ABSTRACT FROM AUTHOR]

The presence of neutral hydrogen in the interstellar medium (ISM) and intergalactic medium (IGM) induces radiative transfer (RT) effects on |$\rm {Ly}\,\alpha$| photons that affect the observability of Lyman alpha emitters (LAEs). We use the galform semi-analytic model of galaxy formation and evolution to analyse how these effects shape the spatial distribution of LAEs with respect to |$\rm {H}\,\alpha$| emitters (HAEs) around high-density regions at high redshift. We find that when a large sample of protoclusters is considered, HAEs showing also |$\rm {Ly}\,\alpha$| emission (HAEs + LAEs) populate the same regions as those that do not display the |$\rm {Ly}\,\alpha$| line at |$z$|  = 2.2. We compare against the protocluster USS1558-003, one of the most massive protoclusters located at |$z$|  = 2.53. Our results indicate that the strong depletion of HAEs + LAEs present in the high-density regions of USS1558-003 may be due to cosmic variance. We find that at |$z$|  = 2.2 and |$z$|  = 3.0, RT of the ISM produces a strong decline (30–50 per cent) of the clustering amplitude of HAEs + LAEs with respect to HAEs towards the protoclusters centre. At |$z$|  = 5.7, given the early evolutionary state of protoclusters and galaxies, the clustering of HAEs + LAEs has a smaller variation (10–20 per cent) towards the protoclusters centre. Depending on the equivalent width and luminosity criteria of the emission-line galaxy sample, the IGM can have a mild or a null effect on galaxy properties and clustering in high-density regions. [ABSTRACT FROM AUTHOR]

We use the semi-analytic model of galaxy formation sag  to study the relevance of mass and environmental quenching on satellite galaxies. We find that environmental processes dominate the star formation (SF) quenching of low-mass satellites (⁠|$M_{\star } \lesssim 10^{10.5}\, {\rm M}_{\odot }$|⁠), whereas high-mass galaxies typically quench as centrals. High-mass galaxies that remain actively forming stars while being accreted are found to be mainly affected by mass quenching after their first infall. For a given stellar mass, our model predicts SF quenching to be less efficient in low-mass haloes both before and after infall, in contradiction with common interpretations of observational data. Our model supports a two-stage scenario to explain the SF quenching. Initially, the SF of satellites resembles that of centrals until the gas cooling rate is reduced to approximately half its value at infall. Then, the SF fades through secular processes that exhaust the cold gas reservoir. This reservoir is not replenished efficiently due to the action of either ram-pressure stripping of the hot gas in low-mass satellites, or feedback from the active galactic nucleus in high-mass satellites. The delay times for the onset of SF quenching are found to range from |${\approx } 3$| to |${\approx } 1\, {\rm Gyr}$| for low-mass (⁠|$M_{\star } \approx 10^{10}\, {\rm M}_{\odot }$|⁠) and high-mass (⁠|$M_{\star } \approx 10^{11}\, {\rm M}_{\odot }$|⁠) satellites, respectively. SF fades in |${\approx } 1\, {\rm Gyr}$|⁠, largely independent of stellar mass. We find that the SF quenching of low-mass satellites supports the so-called delay-then-rapid quenching scenario. However, the SF history of |$z$|  = 0 passive satellites of any stellar mass is better described by a delay-then-fade quenching scenario. [ABSTRACT FROM AUTHOR]

We use the semi-analytic model (SAM) of galaxy formation and evolution sag coupled with the multidark simulation MDPL2 to study the evolution of the stellar – gas metallicity relation of galaxies (MZR). We test several implementations of the dependence of the mass loading due to supernovae (SNe). We find that no evolution in the normalization of the MZR is obtained unless we introduce an explicit scaling of the reheated and ejected mass with redshift as (1 + |$z$|⁠)β. The latter is in agreement with results from the FIRE simulations, and it should encompass small-scale properties of the interstellar medium varying over time, which are not captured in SAMs, as well as other energy sources in addition to SNe. Increasing β leads to stronger evolution of the MZR normalization; β = 1.9 reproduces the observed MZR in the range 0 < |$z$| < 3.5. A stronger redshift dependence of outflows reduces the levels of star formation at earlier epochs with the consequent decrease of metal production. This leads to a slower increase of the gas metallicity compared to the stellar mass build-up. The cold gas can be contaminated either by receiving a direct injection of the material recycled by stellar winds and SNe or by gas cooling. The relative role of each process for a given stellar mass depends on the criterion adopted to regulate the fate of the recycled material. However, modifying the metal loading of the outflows has mild impact on the zero-point evolution and does not affect our conclusions. [ABSTRACT FROM AUTHOR]

Galaxy surveys targeting emission lines are characterizing the evolution of star-forming galaxies, but there is still little theoretical progress in modelling their physical properties. We predict nebular emission from star-forming galaxies within a cosmological galaxy formation model. Emission lines are computed by combining the semi-analytical model sag with the photoionization code mappings-iii. We characterize the interstellar medium of galaxies by relating the ionization parameter of gas in galaxies to their cold gas metallicity, obtaining a reasonable agreement with the observed Hα, [O ii] λ 3727, [O iii] λ 5007 luminosity functions, and the BPT diagram for local star-forming galaxies. The average ionization parameter is found to increase towards low star formation rates and high redshifts, consistent with recent observational results. The predicted link between different emission lines and their associated star formation rates is studied by presenting scaling relations to relate them. Our model predicts that emission-line galaxies have modest clustering bias, and thus reside in dark matter haloes of masses below Mhalo ≲ 1012 [h−1 M⊙]. Finally, we exploit our modelling technique to predict galaxy number counts up to z ∼ 10 by targeting far-infrared emission lines detectable with submillimetre facilities. [ABSTRACT FROM PUBLISHER]