General
How galaxies formed and evolved through cosmic time is one of the key questions of modern astronomy and astrophysics. Cosmological time- and length-scales are so large that the evolution of individual galaxies cannot be directly observed. Only through numerical simulations can one follow the emergence of cosmic structures within the current cosmological paradigm.
The main physical processes in galaxy formation and evolution are gravity, hydrodynamics, gas cooling, star formation, stellar evolution, supernova (SN) and black hole (BH) feedback. These are highly non-linear, thus difficult to describe with analytic models. Moreover, the presence of baryonic matter induces biases that collisionless (“dark matter”) simulations alone cannot reproduce (e.g. van Daalen et al. 2014, MNRAS, 440, 2997; Velliscig et al. 2014, MNRAS, 442, 2641). Semi-analytic models based on these simulations require ad hoc corrections to account for these biases. Hydrodynamic, cosmological simulations are therefore the preferred tool for conducting “controlled experiments” of galaxy formation and evolution.
After three decades of advances in numerical simulations, theorists have only recently been able to reproduce simultaneously the observed properties of the present day galaxy population and the inter-galactic medium (e.g. EAGLE, Schaye et al. 2015, MNRAS, 446, 521; ILLUSTRIS, Vogelsberger et al., 2014, Nature, 509, 177). In particular, the luminosity and mass function of galaxies, the galaxy size- and metallicity-mass relations, and many other properties are now reproduced over a large range of galaxy stellar masses.
The group of numerical astrophysics work on a variety of scientific topics related to the evolution of galaxies and the large-scale structure of the universe. The expertise ranges from the internal structure of dwarf and low surface brightness galaxies, the Milky Way and its satellite galaxies, the study of galaxies in groups and clusters, to large, cosmological simulations of the structure of the universe. The group collaborates with most of the IAC research groups working on extragalactic astrophysics and cosmology.
Members
Results
EDGE/C-EAGLE With the completion of the main sample of simulations, the post-processing phase has been started. Dalla Vecchia developed an analysis program to compute luminosities of SSPs and magnitudes of galaxies of ~30 resimulated clusters. The code makes use of the stellar spectra library EMILES, developed at the IAC and recently extended to cover a larger wavelength range. EUCLID Within the EUCLID collaboration, a total of 300 cosmological, N-body simulations of a volume representative of the observed universe were performed. The same sample of initial conditions was evolved with different techniques by other members of the collaboration. The comparison of the different techniques will allow to assess their accuracy in the estimation of the covariance matrix, thus the errors in the measurements from large-scale structure surveys. GALAXY INTERACTIONS IN CLUSTERS For several decades, it has been known that stellar bars in disc galaxies can be triggered by interactions, or by internal processes such as dynamical instabilities. Martínez-Valpuesta et al. (2017) explore the differences between these two mechanisms using numerical simulations. They used two groups of simulations based on isolated galaxies, one group in which a bar develops naturally, and another group in which the bar could not develop in isolation. The rest of the simulations recreate 1:1 coplanar fly-by interactions computed with the impulse approximation. Compared with equivalent isolated galaxies, they find that bars affected or triggered by interactions: (i) remain in the slow regime for longer, (ii) are boxier in face-on views and (iii) they host kinematically hotter discs. Within this set of simulations, strong differences between retrograde or prograde fly-bys are not seen. They also show that slow interactions can trigger bar formation.
Scientific activity
Related publications
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A high fidelity Milky Way simulation with Kraken, Gaia-Enceladus, and Sequoia analogues: clues to their accretion historiesWithin a simulated Milky Way-like galaxy, we identify and analyse analogues of the Gaia-Enceladus (GE), Kraken, and Sequoia mergers that each matches remarkably well observational results, including in velocity and chemical abundance space, and their distributions in the j z-Energy plane. The Kraken analogue is the earliest merger and has theGarcía-Bethencourt, Guacimara et al.
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Constraining gas metal mixing strength in simulations using observations of the Milky Way's discThis work explores the mixing rate of metals in the interstellar medium (ISM), comparing observational constraints from our solar neighbourhood to high resolution cosmological hydrodynamical simulations of Milky Way (MW)-like galaxies. The mixing rate, described by the coefficient C, is varied in simulations between 0 and 0.05, with resultantSarrato-Alós, J. et al.
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Cosmic gas highways in C-EAGLE simulationsContext. A substantial fraction of cosmic baryons is expected to hide in the form of diffuse warm-hot intergalactic medium (WHIM) at X-ray temperatures (T = 10 5 − 10 7 K). Due to the expected low density of WHIM, it has been very difficult to detect so far. A statistically significant sample of credible detections of the WHIM phase might helpVurm, I. et al.
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On the anticorrelation between pericentric distance and inner dark matter density of Milky Way's dwarf spheroidal galaxiesAn anticorrelation between the central density of the dark matter (DM) halo (ρ 150, DM) and the pericentric distances (r p) of the Milky Way's (MW's) dwarf spheroidal galaxies (dSphs) has been reported in the literature. The existence and origin of such anticorrelation are, however, controversial, one possibility being that only the densest dSphsCardona-Barrero, Salvador et al.
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The Undiscovered Ultradiffuse Galaxies of the Local GroupUltradiffuse galaxies (UDGs) are attractive candidates to probe cosmological models and test theories of galaxy formation at low masses; however, they are difficult to detect because of their low surface brightness. In the Local Group a handful of UDGs have been found to date, most of which are satellites of the Milky Way and M31, and only two areNewton, Oliver et al.
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A probabilistic deep learning model to distinguish cusps and cores in dwarf galaxiesNumerical simulations within a cold dark matter (DM) cosmology form haloes 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 DMExpósito-Márquez, J. et al.
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A probabilistic deep learning model to distinguish cusps and cores in dwarf galaxiesNumerical 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
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Metallicity profiles of ultradiffuse galaxies in NIHAO simulationsSupernovae feedback driven expansion has proven to be a viable mechanism to explain the average properties, such as size, colour, mass, and internal kinematics, of a large fraction of ultradiffuse galaxies (UDGs). Here, we explore the origin of stellar metallicity gradients in feedback driven simulated UDGs from the NIHAO project and compare themCardona-Barrero, S. et al.
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Linking the internal properties of infant globular clusters to their formation environmentsWe investigate the formation of infant globular cluster (GC) candidates in high-resolution cosmological simulations from the First Billion Years project. By analysing the evolution of the systems in the energy and angular momentum plane, we identify the redshift at which the infant GCs first became gravitationally bound, and we find evidence ofPhipps, Frederika et al.
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Mesh-free hydrodynamics in PKDGRAV3 for galaxy formation simulationsWe extend the state-of-the-art N-body code PKDGRAV3 with the inclusion of mesh-free gas hydrodynamics for cosmological simulations. Two new hydrodynamic solvers have been implemented, the mesh-less finite volume and mesh-less finite mass methods. The solvers manifestly conserve mass, momentum, and energy, and have been validated with a wide rangeAlonso Asensio, Isaac et al.
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The luminosity of cluster galaxies in the Cluster-EAGLE simulationsWe computed the luminosity of simulated galaxies of the C-EAGLE project, a suite of 30 high-resolution zoom-in simulations of galaxy clusters based on the EAGLE simulation. The AB magnitudes are derived for different spectral bands, from ultraviolet to infrared, using the simple stellar population modelling based on the E-MILES stellar spectraNegri, Andrea et al.
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92022 -
NIHAO-LG: the uniqueness of Local Group dwarf galaxiesRecent 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 HundredArora, Nikhil et al.
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Observed versus simulated halo c-M<SUB>vir</SUB> relationsThe concentration - virial mass relation is a well-defined trend that reflects the formation of structure in an expanding universe. Numerical simulations reveal a marked correlation that depends on the collapse time of dark matter haloes and their subsequent assembly history. However, observational constraints are mostly limited to the massive end
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FOREVER22: galaxy formation in protocluster regionsWe present results from a new cosmological hydrodynamics simulation campaign of protocluster (PC) regions, FOREVER22: FORmation and EVolution of galaxies in Extremely overdense Regions motivated by SSA22. The simulations cover a wide range of cosmological scales using three different zoom set-ups in a parent volume of $(714.2~\rm cMpc)^{3}$: PCRYajima, Hidenobu et al.
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Formation of the first galaxies in the aftermath of the first supernovaeWe perform high-resolution cosmological hydrodynamic simulations to study the formation of the first galaxies that reach the masses of 10 8 - 9 h -1 M ⊙ at z = 9. The resolution of the simulations is high enough to resolve minihaloes and allow us to successfully pursue the formation of multiple Population (Pop) III stars, their supernova (SN)Abe, Makito et al.
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122021 -
A Shallow Dark Matter Halo in Ultra-diffuse Galaxy AGC 242019: Are UDGs Structurally Similar to Low-surface-brightness Galaxies?A central question regarding ultra-diffuse galaxies (UDGs) is whether they are in a separate category from low-surface-brightness (LSB) galaxies, or just their natural continuation toward 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 an inner slope thatBrook, Chris B. et al.
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Pericentric passage-driven star formation in satellite galaxies and their hosts: CLUES from local group simulationsLocal Group satellite galaxies show a wide diversity of star formation histories (SFHs) whose origin is yet to be fully understood. Using hydrodynamical simulations from the Constrained Local UniversE project, we study the SFHs of satellites of Milky Way-like galaxies in a cosmological context: while in the majority of the cases the accretion on toDi Cintio, Arianna et al.
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Origin of stellar prolate rotation in a cosmologically simulated faint dwarf galaxyStellar prolate rotation in dwarf galaxies is rather uncommon, with only two known galaxies in the Local Group showing such feature (Phoenix and And II). Cosmological simulations show that in massive early-type galaxies prolate rotation likely arises from major mergers. However, the origin of such kinematics in the dwarf galaxies regime has onlyCardona-Barrero, Salvador et al.
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History of the gas fuelling star formation in EAGLE galaxiesTheory predicts that cosmological gas accretion plays a fundamental role fuelling star formation in galaxies. However, a detailed description of the accretion process to be used when interpreting observations is still lacking. Using the state-of-the-art cosmological hydrodynamical simulation EAGLE, we work out the chemical inhomogeneities arisingScholz-Díaz, Laura et al.
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Higher order Hamiltonian Monte Carlo sampling for cosmological large-scale structure analysisWe investigate higher order symplectic integration strategies within Bayesian cosmic density field reconstruction methods. In particular, we study the fourth-order discretization of Hamiltonian equations of motion (EoM). This is achieved by recursively applying the basic second-order leap-frog scheme (considering the single evaluation of the EoM)Hernández-Sánchez, Mónica et al.
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42021
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