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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NIHAO - XIV. Reproducing the observed diversity of dwarf galaxy rotation curve shapes in ΛCDMThe significant diversity of rotation curve (RC) shapes in dwarf galaxies has recently emerged as a challenge to Λ cold dark matter (ΛCDM): in dark matter (DM) only simulations, DM haloes have a universal cuspy density profile that results in self-similar RC shapes. We compare RC shapes of simulated galaxies from the NIHAO (Numerical InvestigationSantos-Santos, Isabel M. et al.
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22018 -
The Cluster-EAGLE project: velocity bias and the velocity dispersion-mass relation of cluster galaxiesWe use the Cluster-EAGLE simulations to explore the velocity bias introduced when using galaxies, rather than dark matter particles, to estimate the velocity dispersion of a galaxy cluster, a property known to be tightly correlated with cluster mass. The simulations consist of 30 clusters spanning a mass range 14.0 ≤ log10(M200 c/M⊙) ≤ 15.4, withArmitage, T. J. et al.
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32018 -
Galactic wind X-ray heating of the intergalactic medium during the Epoch of ReionizationThe diffuse soft X-ray emissivity from galactic winds is computed during the Epoch of Reionization (EoR). We consider two analytic models, a pressure-driven wind and a superbubble model, and a 3D cosmological simulation including gas dynamics from the First Billion Years (FiBY) project. The analytic models are normalized to match the diffuse X-rayMeiksin, A. et al.
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Growth of First Galaxies: Impacts of Star Formation and Stellar FeedbackRecent observations have detected galaxies at high-redshift z∼ 6{--}11, and revealed the diversity of their physical properties, from normal star-forming galaxies to starburst galaxies. To understand the properties of these observed galaxies, it is crucial to understand the star formation (SF) history of high-redshift galaxies under the influenceYajima, H. et al.
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92017 -
The Radial Distribution of Mono-metallicity Populations in the Galactic Disk as Evidence for Two-phase Disk FormationRecent determinations of the radial distributions of mono-metallicity populations (MMPs, i.e., stars in narrow bins in [Fe/H] within wider [α/Fe] ranges) by the SDSS-III/APOGEE DR12 survey cast doubts on the classical thin- and thick-disk dichotomy. The analysis of these observations led to the non-[α /Fe] enhanced populations splitting into MMPsDomínguez-Tenreiro, R. et al.
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92017 -
The First Billion Years project: constraining the dust attenuation law of star-forming galaxies at z ≃ 5We present the results of a study investigating the dust attenuation law at z ≃ 5, based on synthetic spectral energy distributions (SEDs) calculated for a sample of N = 498 galaxies drawn from the First Billion Years (FiBY) simulation project. The simulated galaxies at z ≃ 5, which have M1500 ≤ -18.0 and 7.5 ≤ log(M/M}_{⊙}) ≤ 10.2, display a massCullen, F. et al.
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92017 -
The Hydrangea simulations: galaxy formation in and around massive clustersWe introduce the Hydrangea simulations, a suite of 24 cosmological hydrodynamic zoom-in simulations of massive galaxy clusters (M200c = 1014-1015.4 M⊙) with baryon particle masses of ˜106 M⊙. Designed to study the impact of the cluster environment on galaxy formation, they are a key part of the `Cluster-EAGLE' project. They use a galaxy formationBahé, Y. M. et al.
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102017 -
The Cluster-EAGLE project: global properties of simulated clusters with resolved galaxiesWe introduce the Cluster-EAGLE (c-eagle) simulation project, a set of cosmological hydrodynamical zoom simulations of the formation of 30 galaxy clusters in the mass range of 1014 M200/M⊙ 1015.4 that incorporates the Hydrangea sample of Bahé et al. (2017). The simulations adopt the state-of-the-art eagle galaxy formation model, with a gasBarnes, D. J. et al.
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102017 -
Diversity of dwarf galaxy IR-submm emission patterns: CLUES from hydrodynamical simulationsContext. The spectral energy distributions (SEDs) of low-mass low-metallicity (dwarf) galaxies are a challenging piece of the puzzle of galaxy formation in the near Universe. These SEDs show some particular features in the submillimeter to far-infrared (FIR) wavelength range compared to normal larger galaxies that cannot be explained by the currentSantos-Santos, Isabel M. E. et al.
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62017 -
Barred galaxies in the EAGLE cosmological hydrodynamical simulationWe examine the properties of barred disc galaxies in a ΛCDM cosmological hydrodynamical simulation from the EAGLE project. Our study follows the formation of 269 discs identified at z = 0 in the stellar mass range 10.6 log M*/M⊙ 11. These discs show a wide range of bar strengths, from unbarred discs (≈60 per cent) to weak bars (≈20 per cent) andSchaye, Joop et al.
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72017 -
Sloan Digital Sky Survey IV: Mapping the Milky Way, Nearby Galaxies, and the Distant UniverseWe describe the Sloan Digital Sky Survey IV (SDSS-IV), a project encompassing three major spectroscopic programs. The Apache Point Observatory Galactic Evolution Experiment 2 (APOGEE-2) is observing hundreds of thousands of Milky Way stars at high resolution and high signal-to-noise ratios in the near-infrared. The Mapping Nearby Galaxies at ApacheMao, Shude et al.
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72017 -
Deep spectroscopy in nearby galaxy clusters - III. Orbital structure of galaxies in Abell 85Galaxies in clusters are strongly affected by their environment. They evolve according to several physical mechanisms that are active in clusters. Their efficiency can strongly depend on the orbital configuration of the galaxies. Our aim is to analyse the orbits of the galaxies in the cluster Abell 85, based on the study of the galaxy velocityAguerri, J. A. L. et al.
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62017 -
The clustering of galaxies in the completed SDSS-III Baryon Oscillation Spectroscopic Survey: Cosmological implications of the Fourier space wedges of the final sampleWe extract cosmological information from the anisotropic power-spectrum measurements from the recently completed Baryon Oscillation Spectroscopic Survey (BOSS), extending the concept of clustering wedges to Fourier space. Making use of new fast-Fourier-transform-based estimators, we measure the power-spectrum clustering wedges of the BOSS sample byGrieb, Jan Niklas et al.
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52017 -
Testing the conditional mass function of dark matter haloes against numerical N-body simulationsWe compare the predicted conditional mass function (CMF) of dark matter haloes from two theoretical prescriptions against numerical N-body simulations, both in overdense and underdense regions and at different Eulerian scales ranging from 5 to 30 h-1 Mpc. In particular, we consider in detail a locally implemented rescaling of the unconditional massTramonte, D. et al.
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52017 -
NIHAO - XI. Formation of ultra-diffuse galaxies by outflowsWe address the origin of ultra-diffuse galaxies (UDGs), which have stellar masses typical of dwarf galaxies but effective radii of Milky Way-sized objects. Their formation mechanism, and whether they are failed L⋆ galaxies or diffuse dwarfs, are challenging issues. Using zoom-in cosmological simulations from the Numerical Investigation of a HundredDi Cintio, A. et al.
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32017 -
The Spectral Evolution of the First Galaxies. III. Simulated James Webb Space Telescope Spectra of Reionization-epoch Galaxies with Lyman-continuum LeakageUsing four different suites of cosmological simulations, we generate synthetic spectra for galaxies with different Lyman-continuum escape fractions (f esc) at redshifts z≈ 7–9, in the rest-frame wavelength range relevant for the James Webb Space Telescope (JWST) NIRSpec instrument. By investigating the effects of realistic star formation historiesZackrisson, E. et al.
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22017 -
On the Dearth of Ultra-faint Extremely Metal-poor GalaxiesLocal extremely metal-poor galaxies (XMPs) are of particular astrophysical interest since they allow us to look into physical processes characteristic of the early universe, from the assembly of galaxy disks to the formation of stars in conditions of low metallicity. Given the luminosity–metallicity relationship, all galaxies fainter than M r ≃ ‑13Sánchez Almeida, J. et al.
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22017 -
The Aurora radiation-hydrodynamical simulations of reionization: calibration and first resultsWe introduce a new suite of radiation-hydrodynamical simulations of galaxy formation and reionization called Aurora. The Aurora simulations make use of a spatially adaptive radiative transfer technique that lets us accurately capture the small-scale structure in the gas at the resolution of the hydrodynamics, in cosmological volumes. In addition toPawlik, A. H. et al.
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42017 -
A numerical study of interactions and stellar barsFor 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. In this work, we explore the differences between these two mechanisms using numerical simulations. We perform two groups of simulations based on isolated galaxies, one group in which aMartinez-Valpuesta, I. et al.
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12017 -
The clustering of galaxies in the completed SDSS-III Baryon Oscillation Spectroscopic Survey: Cosmological implications of the configuration-space clustering wedgesWe explore the cosmological implications of anisotropic clustering measurements in configuration space of the final galaxy samples from Data Release 12 of the Sloan Digital Sky Survey III Baryon Oscillation Spectroscopic Survey. We implement a new detailed modelling of the effects of non-linearities, bias and redshift-space distortions that can beSánchez, A. G. et al.
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