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 XXI: the emergence of low surface brightness galaxiesThe existence of galaxies with a surface brightness μ lower than the night sky has been known since three decades. Yet, their formation mechanism and emergence within a Lambda cold dark matter universe has remained largely undetermined. For the first time, we investigated the origin of low surface brightness (LSB) galaxies with M⋆ ˜ 109.5-10 M⊙Di Cintio, A. et al.
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62019 -
The signal of decaying dark matter with hydrodynamical simulationsDark matter particles may decay, emitting photons. Drawing on the EAGLE family of hydrodynamical simulations of galaxy formation - including the APOSTLE and C-EAGLE simulations - we assess the systematic uncertainties and scatter on the decay flux from different galaxy classes, from Milky Way satellites to galaxy clusters, and compare our resultsLovell, M. R. et al.
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52019 -
Disruption of satellite galaxies in simulated groups and clusters: the roles of accretion time, baryons, and pre-processingWe investigate the disruption of group and cluster satellite galaxies with total mass (dark matter plus baryons) above 10^{10} M_⊙ in the Hydrangea simulations, a suite of 24 high-resolution cosmological hydrodynamical zoom-in simulations based on the EAGLE model. The simulations predict that ˜50 per cent of satellites survive to redshift z = 0Bahé, Y. M. et al.
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52019 -
Comparing approximate methods for mock catalogues and covariance matrices II: power spectrum multipolesWe study the accuracy of several approximate methods for gravitational dynamics in terms of halo power spectrum multipoles and their estimated covariance matrix. We propagate the differences in covariances into parameter constraints related to growth rate of structure, Alcock-Paczynski distortions, and biasing. We consider seven methods in threeBlot, L. et al.
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52019 -
Dark matter response to galaxy assembly historyAims: It is well known that the presence of baryons affects the dark matter host haloes. Exploring the galaxy assembly history together with the dark matter haloes properties through time can provide a way to measure these effects. Methods: We have studied the properties of four Milky Way mass dark matter haloes from the Aquarius project duringArtale, M. C. et al.
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22019 -
Galaxies with monstrous black holes in galaxy cluster environmentsMassive early-type galaxies follow a tight relation between the mass of their central supermassive black hole (MBH) and their stellar mass (M⋆). The origin of observed positive outliers from this relation with extremely high MBH (> 109 M_{⊙ }) remains unclear. We present a study of such outliers in the Hydrangea/C-EAGLE cosmological hydrodynamicalvan Son, Lieke A. C. et al.
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52019 -
Comparing approximate methods for mock catalogues and covariance matrices - I. Correlation functionThis paper is the first in a set that analyses the covariance matrices of clustering statistics obtained from several approximate methods for gravitational structure formation. We focus here on the covariance matrices of anisotropic two-point correlation function measurements. Our comparison includes seven approximate methods, which can be dividedLippich, M. et al.
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12019 -
The Cluster-EAGLE project: a comparison of dynamical mass estimators using simulated clustersForthcoming large-scale spectroscopic surveys will soon provide data on thousands of galaxy clusters. It is important that the systematics of the various mass estimation techniques is well understood and calibrated. We compare three different dynamical mass estimators using the C-EAGLE galaxy clusters, a set of high-resolution simulations withArmitage, Thomas J. et al.
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12019 -
Comparing approximate methods for mock catalogues and covariance matrices - III: bispectrumWe compare the measurements of the bispectrum and the estimate of its covariance obtained from a set of different methods for the efficient generation of approximate dark matter halo catalogues to the same quantities obtained from full N-body simulations. To this purpose we employ a large set of 300 realizations of the same cosmology for eachColavincenzo, Manuel et al.
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22019 -
A case study of hurdle and generalized additive models in astronomy: the escape of ionizing radiationThe dark ages of the Universe end with the formation of the first generation of stars residing in primeval galaxies. These objects were the first to produce ultraviolet ionizing photons in a period when the cosmic gas changed from a neutral state to an ionized one, known as Epoch of Reionization (EoR). A pivotal aspect to comprehend the EoR is toHattab, M. W. et al.
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32019 -
Gaia DR2 proper motions of dwarf galaxies within 420 kpc. Orbits, Milky Way mass, tidal influences, planar alignments, and group infallA proper understanding of the Milky Way (MW) dwarf galaxies in a cosmological context requires knowledge of their 3D velocities and orbits. However, proper motion (PM) measurements have generally been of limited accuracy and are available only for more massive dwarfs. We therefore present a new study of the kinematics of the MW dwarf galaxies. WeFritz, T. K. et al.
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112018 -
Stellar feedback and the energy budget of late-type Galaxies: missing baryons and core creationIn a ΛCDM cosmology, galaxy formation is a globally inefficient process: it is often the case that far fewer baryons are observed in galaxy discs than expected from the cosmic baryon fraction. The location of these `missing baryons' is unclear. By fitting halo profiles to the rotation curves of galaxies in the SPARC data set, we measure theKatz, H. et al.
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112018 -
CLUES about M33: the reversed radial stellar age gradient in the outskirts of Triangulum galaxyHST/ACS observations along the major axis of M33 show that the mean age of its stars decreases with increasing distance from the galaxy centre. Such a behaviour is consistent with an inside-out growth of the disc. However, in the outermost observed field, at r ≃ 11.6 kpc, a reversal of this gradient is detected, with old stars found in highMostoghiu, R. et al.
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112018 -
On the early evolution of Local Group dwarf galaxy types: star formation and supernova feedbackAccording to star formation histories (SFHs), Local Group dwarf galaxies can be broadly classified in two types: those forming most of their stars before z = 2 (fast) and those with more extended SFHs (slow). The most precise SFHs are usually derived from deep but not very spatially extended photometric data; this might alter the ratio of old toBermejo-Climent, J. R. et al.
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92018 -
Spectroscopic characterization of the stellar content of ultra-diffuse galaxiesUnderstanding the peculiar properties of ultra-diffuse galaxies (UDGs) via spectroscopic analysis is a challenging task requiring very deep observations and exquisite data reduction. In this work, we perform one of the most complete characterizations of the stellar component of UDGs to date using deep optical spectroscopic data from OSIRIS at GranRuiz-Lara, T. et al.
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82018 -
Signatures of the Galactic bar on stellar kinematics unveiled by APOGEEBars are common galactic structures in the local universe that play an important role in the secular evolution of galaxies, including the Milky Way. In particular, the velocity distribution of individual stars in our galaxy is useful to shed light on stellar dynamics, and provides information complementary to that inferred from the integrated lightPalicio, P. A. et al.
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72018 -
The Origin of the Relation between Metallicity and Size in Star-forming GalaxiesFor the same stellar mass, physically smaller star-forming galaxies are also metal richer. What causes the relation remains unclear. The central star-forming galaxies in the EAGLE cosmological numerical simulation reproduce the observed trend. We use them to explore the origin of the relation assuming that the physical mechanism responsible for theSánchez Almeida, J. et al.
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62018 -
Active Galactic Nuclei Feedback and the Origin and Fate of the Hot Gas in Early-type GalaxiesA recent determination of the relationships between the X-ray luminosity of the ISM (L X) and the stellar and total mass for a sample of nearby early-type galaxies (ETGs) is used to investigate the origin of the hot gas, via a comparison with the results of hydrodynamical simulations of the ISM evolution for a large set of isolated ETGs. After thePellegrini, S. et al.
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42018 -
The VANDELS survey: dust attenuation in star-forming galaxies at z = 3-4We present the results of a new study of dust attenuation at redshifts 3 z 4 based on a sample of 236 star-forming galaxies from the VANDELS spectroscopic survey. Motivated by results from the First Billion Years (FiBY) simulation project, we argue that the intrinsic spectral energy distributions (SEDs) of star-forming galaxies at these redshiftsCullen, F. et al.
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52018 -
The diverse density profiles of galaxy clusters with self-interacting dark matter plus baryonsWe present the first simulated galaxy clusters (M200 > 1014 M⊙) with both self-interacting dark matter (SIDM) and baryonic physics. They exhibit a greater diversity in both dark matter and stellar density profiles than their counterparts in simulations with collisionless dark matter (CDM), which is generated by the complex interplay between darkBarnes, David J. et al.
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52018
