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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The EAGLE simulations of galaxy formation: the importance of the hydrodynamics schemeWe present results from a subset of simulations from the `Evolution and Assembly of GaLaxies and their Environments' (EAGLE) suite in which the formulation of the hydrodynamics scheme is varied. We compare simulations that use the same subgrid models without recalibration of the parameters but employing the standard GADGET flavour of smoothedSchaller, M. et al.
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122015 -
The BaLROG project - I. Quantifying the influence of bars on the kinematics of nearby galaxiesWe present the BaLROG (Bars in Low Redshift Optical Galaxies) sample of 16 morphologically distinct barred spirals to characterize observationally the influence of bars on nearby galaxies. Each galaxy is a mosaic of several pointings observed with the integral-field unit (IFU) SAURON leading to a tenfold sharper spatial resolution (˜100 pc)Seidel, M. K. et al.
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72015 -
Hα kinematics of S4G spiral galaxies - II. Data description and non-circular motionsWe present a kinematical study of 29 spiral galaxies included in the Spitzer Survey of Stellar Structure in Galaxies, using Hα Fabry-Perot (FP) data obtained with the Galaxy Hα Fabry-Perot System instrument at the William Herschel Telescope in La Palma, complemented with images in the R band and in Hα. The primary goal is to study the evolution andErroz-Ferrer, S. et al.
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72015 -
Colours and luminosities of z = 0.1 galaxies in the EAGLE simulationWe calculate the colours and luminosities of redshift z = 0.1 galaxies from the EAGLE simulation suite using the GALAXEV population synthesis models. We take into account obscuration by dust in birth clouds and diffuse interstellar medium using a two-component screen model, following the prescription of Charlot and Fall. We compare models in whichTrayford, J. W. et al.
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92015 -
Molecular hydrogen abundances of galaxies in the EAGLE simulationsWe investigate the abundance of galactic molecular hydrogen (H2) in the `Evolution and Assembly of GaLaxies and their Environments' (EAGLE) cosmological hydrodynamic simulations. We assign H2 masses to gas particles in the simulations in post-processing using two different prescriptions that depend on the local dust-to-gas ratio and theLagos, C. P. et al.
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102015 -
The alignment and shape of dark matter, stellar, and hot gas distributions in the EAGLE and cosmo-OWLS simulationsWe report the alignment and shape of dark matter, stellar, and hot gas distributions in the EAGLE (Evolution and Assembly of GaLaxies and their Environments) and cosmo-OWLS (OverWhelmingly Large Simulations) simulations. The combination of these state-of-the-art hydrodynamical cosmological simulations enables us to span four orders of magnitude inTheuns, Tom et al.
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102015 -
The effect of baryons on the inner density profiles of rich clustersWe use the `Evolution and assembly of galaxies and their environments' (EAGLE) cosmological simulation to investigate the effect of baryons on the density profiles of rich galaxy clusters. We focus on EAGLE clusters with M200 > 1014 M⊙ of which we have six examples. The central brightest cluster galaxies (BCGs) in the simulation have steep stellarMcCarthy, I. G. et al.
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92015 -
Baryon effects on the internal structure of ΛCDM haloes in the EAGLE simulationsWe investigate the internal structure and density profiles of haloes of mass 1010-1014 M⊙ in the Evolution and Assembly of Galaxies and their Environment (EAGLE) simulations. These follow the formation of galaxies in a Λ cold dark matter Universe and include a treatment of the baryon physics thought to be relevant. The EAGLE simulations reproduceSchaller, Matthieu et al.
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82015 -
Spatially adaptive radiation-hydrodynamical simulations of galaxy formation during cosmological reionizationWe present a suite of cosmological radiation-hydrodynamical simulations of the assembly of galaxies driving the reionization of the intergalactic medium (IGM) at z ≳ 6. The simulations account for the hydrodynamical feedback from photoionization heating and the explosion of massive stars as supernovae (SNe). Our reference simulation, which wasPawlik, A. H. et al.
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82015 -
The First Billion Years project: the escape fraction of ionizing photons in the epoch of reionizationProtogalaxies forming in low-mass dark matter haloes are thought to provide the majority of ionizing photons needed to reionize the Universe, due to their high escape fractions of ionizing photons. We study how the escape fraction in high-redshift galaxies relates to the physical properties of the halo in which the galaxies form, by computingPaardekooper, J.-P. et al.
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82015 -
Evolution of galaxy stellar masses and star formation rates in the EAGLE simulationsWe investigate the evolution of galaxy masses and star formation rates in the Evolution and Assembly of Galaxies and their Environment (EAGLE) simulations. These comprise a suite of hydrodynamical simulations in a Λ cold dark matter cosmogony with subgrid models for radiative cooling, star formation, stellar mass-loss and feedback from stars andFurlong, M. et al.
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72015 -
On the morphology of dust lanes in galactic barsThe aim of our study is to use dynamical simulations to explore the influence of two important dynamical bar parameters, bar strength and bar pattern speed on the shape of the bar dust lanes. To quantify the shape of the dust lanes we have developed a new systematic method to measure the dust lane curvature. Previous numerical simulations haveSánchez-Menguiano, L. et al.
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72015 -
The EAGLE simulations of galaxy formation: calibration of subgrid physics and model variationsWe present results from 13 cosmological simulations that explore the parameter space of the `Evolution and Assembly of GaLaxies and their Environments' (EAGLE) simulation project. Four of the simulations follow the evolution of a periodic cube L = 50 cMpc on a side, and each employs a different subgrid model of the energetic feedback associatedCrain, R. A. et al.
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62015 -
A cosmological context for compact massive galaxiesTo provide a quantitative cosmological context to ongoing observational work on the formation histories and location of compact massive galaxies, we locate and study a sample of exceptionally compact systems in the BOLSHOI simulation, using the dark matter structural parameters from a real, compact massive galaxy (NGC 1277) as a basis for ourStringer, M. et al.
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52015 -
Bent by baryons: the low-mass galaxy-halo relationThe relation between galaxies and dark matter haloes is of vital importance for evaluating theoretical predictions of structure formation and galaxy formation physics. We use hydrodynamic cosmological simulations of the Local Group to show that the widely used method of abundance matching based on dark matter only simulations fails at the low-massSawala, T. et al.
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42015 -
Made-to-measure models of the Galactic box/peanut bulge: stellar and total mass in the bulge regionWe construct dynamical models of the Milky Way's box/peanut (B/P) bulge, using the recently measured 3D density of red clump giants (RCGs) as well as kinematic data from the Bulge Radial Velocity Assay (BRAVA) survey. We match these data using the NMAGIC made-to-measure method, starting with N-body models for barred discs in different dark matterPortail, M. et al.
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32015 -
The EAGLE project: simulating the evolution and assembly of galaxies and their environmentsWe introduce the Virgo Consortium's Evolution and Assembly of GaLaxies and their Environments (EAGLE) project, a suite of hydrodynamical simulations that follow the formation of galaxies and supermassive black holes in cosmologically representative volumes of a standard Λ cold dark matter universe. We discuss the limitations of such simulations inSchaye, J. et al.
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12015 -
The First Billion Years project: gamma-ray bursts at z > 5Long gamma-ray burst's (LGRB's) association with the death of massive stars suggests that they could be used to probe the cosmic star formation history (CSFH) with high accuracy, due to their high luminosities. We utilize cosmological simulations from the First Billion Years project to investigate the biases between the CSFH and the LGRB rate at zElliott, J. et al.
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22015
