Romain Teyssier

• PhD
• Professor (Associate) at University of Zurich

We present a theoretical framework for calculating the volume filling fraction of galactic outflows in cosmic voids by integrating analytical models for the halo mass function (HMF), the halo occupation fraction, the stellar mass-halo mass relation, and outflow sizes. Using RAMSES, we perform a hydrodynamical zoom-in simulation of the central 25 cM...

We present the Flagship galaxy mock, a simulated catalogue of billions of galaxies designed to support the scientific exploitation of the mission. is a medium-class mission of the European Space Agency optimised to determine the properties of dark matter and dark energy on the largest scales of the Universe. It probes structure formation over more...

The field of high redshift galaxy formation has been revolutionised by JWST, which is yielding unprecedented insights on galaxy assembly at early times. Our key aim is to study the physical mechanisms that can explain the unexpected abundance of bright galaxies at $z \geq 11$, as well as their metal enrichment and spectral properties. We also use r...

Stellar convection poses two main gargantuan challenges for astrophysical fluid solvers: low-Mach number flows and minuscule perturbations over steeply stratified hydrostatic equilibria. Most methods exhibit excessive numerical diffusion and are unable to capture the correct solution due to large truncation errors. In this paper, we analyze the per...

Structure identification in cosmological simulations plays an important role in analysing simulation outputs. The definition of these structures directly impacts the inferred properties derived from these simulations. This paper proposes a more straightforward definition and model of structure by focusing on density peaks rather than halos and clum...

Star formation is a key process that governs the baryon cycle within galaxies, however, the question of how it controls their growth remains elusive due to modeling uncertainties. To understand the impact of star formation models on galaxy evolution, we performed cosmological zoom-in radiation-hydrodynamic simulations of a dwarf dark matter halo, w...

Dispersion measures (DM) of fast radio bursts (FRBs) probe the density of electrons in the intergalactic medium (IGM) along their lines-of-sight, including the average density versus distance to the source and its variations in direction. While previous study focused on low-redshift, FRBs are potentially detectable out to high redshift, where their...

Motivated by the early excess of bright galaxies seen by \textit{JWST}, we run zoom-in cosmological simulations of a massive galaxy at Cosmic Dawn (MDG), in a halo of $10^{11} M_\odot$ at $z = 9$, using the hydro-gravitational code RAMSES at an effective resolution $\sim 10~{\rm pc}$. We investigate physical mechanisms that enhance the star-formati...

Motivated by the need for realistic, dynamically self-consistent, evolving galaxy models that avoid the complexity of full, and zoom-in, cosmological simulations, we have developed Nexus, an integral framework to create and evolve synthetic galaxies made of collisionless and gaseous components. Nexus leverages the power of publicly available, tried...

Recently, NIRSpec PRISM/CLEAR observations by JWST have begun providing rest-frame UV continuum measurements of galaxies at $z\gtrsim7$, revealing signatures of Ly$\alpha$ damping-wing (DW) absorption by the intergalactic medium (IGM). We develop a methodology to constrain the global ionization fraction of the IGM $(Q_{\rm HII})$ using low-resoluti...

Traditional star formation subgrid models implemented in cosmological galaxy formation simulations, such as that of Springel & Hernquist (2003, hereafter SH03), employ adjustable parameters to satisfy constraints measured in the local Universe. In recent years, however, theory and spatially-resolved simulations of the turbulent, multiphase, star-fo...

To understand the impact of star formation models on galaxy evolution, we perform cosmological zoom-in radiation-hydrodynamic simulations of a dwarf dark matter halo with virial mass 1e9 Msun at z=6. Two different star formation models are compared, a model based on a local gravo-thermo-turbulent condition and a model based on a sink particle algor...

In this fourth paper from the AGORA Collaboration, we study the evolution down to redshift z = 2 and below of a set of cosmological zoom-in simulations of a Milky Way mass galaxy by eight of the leading hydrodynamic simulation codes. We also compare this CosmoRun suite of simulations with dark matter-only simulations by the same eight codes. We ana...

Motivated by the need for realistic, dynamically self-consistent, evolving galaxy models that avoid the inherent complexity of full, and zoom-in, cosmological simulations, we have developed Nexus, an integral, flexible framework to create synthetic galaxies made of both collisionless and gaseous components. Nexus leverages the power of publicly ava...

We present the Flagship galaxy mock, a simulated catalogue of billions of galaxies designed to support the scientific exploitation of the Euclid mission. Euclid is a medium-class mission of the European Space Agency optimised to determine the properties of dark matter and dark energy on the largest scales of the Universe. It probes structure format...

Stellar convection poses two main gargantuan challenges for astrophysical fluid solvers: low-Mach number flows and minuscule perturbations over steeply stratified hydrostatic equilibria. Most methods exhibit excessive numerical diffusion and are unable to capture the correct solution due to large truncation errors. In this paper, we analyze the per...

We present the first cosmological constraints using only the observed photometry of galaxies. Villaescusa-Navarro et al. recently demonstrated that the internal physical properties of a single simulated galaxy contain a significant amount of cosmological information. These physical properties, however, cannot be directly measured from observations....

We analyze and compare the satellite halo populations at z ∼ 2 in the high-resolution cosmological zoom-in simulations of a 10 ¹² M ⊙ target halo ( z = 0 mass) carried out on eight widely used astrophysical simulation codes ( Art-I , Enzo , Ramses , Changa , Gadget-3 , Gear , Arepo-t , and Gizmo ) for the AGORA High-resolution Galaxy Simulations Co...

We analyze the circumgalactic medium (CGM) for eight commonly-used cosmological codes in the AGORA collaboration. The codes are calibrated to use identical initial conditions, cosmology, heating and cooling, and star formation thresholds, but each evolves with its own unique code architecture and stellar feedback implementation. Here, we analyze th...

We discover analytic equations that can infer the value of Ω m from the positions and velocity moduli of halo and galaxy catalogs. The equations are derived by combining a tailored graph neural network (GNN) architecture with symbolic regression. We first train the GNN on dark matter halos from Gadget N -body simulations to perform field-level like...

Recent work has pointed out the potential existence of a tight relation between the cosmological parameter Ω m , at fixed Ω b , and the properties of individual galaxies in state-of-the-art cosmological hydrodynamic simulations. In this paper, we investigate whether such a relation also holds for galaxies from simulations run with a different code...

When the first galaxies formed and starlight escaped into the intergalactic medium to reionize it, galaxy formation and reionization were both highly inhomogeneous in time and space, and fully-coupled by mutual feedback. To show how this imprinted the UV luminosity function (UVLF) of reionization-era galaxies, we use our large-scale, radiation-hydr...

We train graph neural networks to perform field-level likelihood-free inference using galaxy catalogs from state-of-the-art hydrodynamic simulations of the CAMELS project. Our models are rotational, translational, and permutation invariant and do not impose any cut on scale. From galaxy catalogs that only contain 3D positions and radial velocities...

We present a suite of high-resolution simulations of an isolated dwarf galaxy using four different hydrodynamical codes: Gizmo , Arepo , Gadget , and Ramses . All codes adopt the same physical model, which includes radiative cooling, photoelectric heating, star formation, and supernova (SN) feedback. Individual SN explosions are directly resolved w...

Recent work has pointed out the potential existence of a tight relation between the cosmological parameter $\Omega_{\rm m}$, at fixed $\Omega_{\rm b}$, and the properties of individual galaxies in state-of-the-art cosmological hydrodynamic simulations. In this paper, we investigate whether such a relation also holds for galaxies from simulations ru...

The formation and evolution of galaxies have proved sensitive to the inclusion of stellar feedback, which is therefore crucial to any successful galaxy model. We present INFERNO, a new model for hydrodynamic simulations of galaxies, which incorporates resolved stellar objects with star-by-star calculations of when and where the injection of enriche...

We discover analytic equations that can infer the value of $\Omega_{\rm m}$ from the positions and velocity moduli of halo and galaxy catalogues. The equations are derived by combining a tailored graph neural network (GNN) architecture with symbolic regression. We first train the GNN on dark matter halos from Gadget N-body simulations to perform fi...

We train graph neural networks to perform field-level likelihood-free inference using galaxy catalogs from state-of-the-art hydrodynamic simulations of the CAMELS project. Our models are rotationally, translationally, and permutation invariant and have no scale cutoff. By training on galaxy catalogs that only contain the 3D positions and radial vel...

We train graph neural networks on halo catalogs from Gadget N -body simulations to perform field-level likelihood-free inference of cosmological parameters. The catalogs contain ≲5000 halos with masses ≳10 ¹⁰ h ⁻¹ M ⊙ in a periodic volume of ( 25 h − 1 Mpc ) 3 ; every halo in the catalog is characterized by several properties such as position, mass...

We present a new numerical scheme which combines the Spectral Difference (SD) method up to arbitrary high order with a-posteriori limiting using the classical MUSCL-Hancock scheme as fallback scheme. It delivers very accurate solutions in smooth regions of the flow, while capturing sharp discontinuities without spurious oscillations. We exploit the...

We present a new numerical scheme which combines the Spectral Difference (SD) method up to arbitrary high order with \emph{a-posteriori} limiting using the classical MUSCL-Hancock scheme as fallback scheme. It delivers very accurate solutions in smooth regions of the flow, while capturing sharp discontinuities without spurious oscillations. We expl...

We train graph neural networks on halo catalogues from Gadget N-body simulations to perform field-level likelihood-free inference of cosmological parameters. The catalogues contain $\lesssim$5,000 halos with masses $\gtrsim 10^{10}~h^{-1}M_\odot$ in a periodic volume of $(25~h^{-1}{\rm Mpc})^3$; every halo in the catalogue is characterized by sever...

The formation and evolution of galaxies have proved sensitive to the inclusion of stellar feedback, which is therefore crucial to any successful galaxy model. We present INFERNO, a new model for hydrodynamic simulations of galaxies, which incorporates resolved stellar objects with star-by-star calculations of when and where the injection of enriche...

Recent determinations of the mean free path of ionising photons (mfp) in the intergalactic medium (IGM) at $\rm z=6$ are lower than many theoretical predictions. In order to gain insight, we investigate the evolution of the mfp in our new massive fully coupled radiation hydrodynamics cosmological simulation of reionization: Cosmic Dawn III (CoDa II...

We present a suite of high-resolution simulations of an isolated dwarf galaxy using four different hydrodynamical codes: {\sc Gizmo}, {\sc Arepo}, {\sc Gadget}, and {\sc Ramses}. All codes adopt the same physical model which includes radiative cooling, photoelectric heating, star formation, and supernova (SN) feedback. Individual SN explosions are...

An initially planar shock wave propagating into a medium of nonuniform density will be perturbed, leading to the generation of postshock velocity perturbations. Using numerical simulations we study this phenomenon in the case of highly nonuniform density (order-unity normalized variance, σ_{ρ}/ρ[over ¯]∼1) and strong shocks (shock Mach numbers M[ov...

An initially planar shock wave propagating into a medium of non-uniform density will be perturbed, leading to the generation of post-shock velocity perturbations. Using numerical simulations we study this phenomenon in the case of highly-non-uniform density (order-unity normalized variance, $\sigma_{\rho}/\overline{\rho} \sim 1$) and strong shocks...

Turbulence in the interstellar medium (ISM) is crucial in the process of star formation. Shocks produced by supernova explosions, jets, radiation from massive stars, or galactic spiral-arm dynamics are amongst the most common drivers of turbulence in the ISM. However, it is not fully understood how shocks drive turbulence, in particular whether sho...

Turbulence in the interstellar medium (ISM) is crucial in the process of star formation. Shocks produced by supernova explosions, jets, radiation from massive stars, or galactic spiral-arm dynamics are amongst the most common drivers of turbulence in the ISM. However, it is not fully understood how shocks drive turbulence, in particular whether sho...

Magnetic fields have been included in cosmological simulations of galaxy formation only recently. In this paper, we develop a new subgrid model for the turbulent dynamo that takes place in the supersonic interstellar medium in star-forming galaxies. It is based on a mean-field approach that computes the turbulent kinetic energy at unresolved scales...

Galaxies can be characterized by many internal properties such as stellar mass, gas metallicity, and star formation rate. We quantify the amount of cosmological and astrophysical information that the internal properties of individual galaxies and their host dark matter halos contain. We train neural networks using hundreds of thousands of galaxies...

Recent determinations of the mean free path of ionising photons (mfp) in the intergalactic medium (IGM) at $\rm z=6$ are lower than many theoretical predictions. In order to gain insight into this issue, we investigate the evolution of the mfp in our new massive fully coupled radiation hydrodynamics cosmological simulation of reionization: Cosmic D...

We investigate the evolution of the dark matter density profiles of the most massive galaxy clusters in the Universe. Using a `zoom-in' procedure on a large suite of cosmological simulations of total comoving volume of $3\,(h^{-1}\,\rm Gpc)^3$, we study the 25 most massive clusters in four redshift slices from $z\sim 1$ to the present. The minimum...

ALMA observations of z > 6 galaxies have revealed abnormally high [OIII]88μm/[CII]158μm ratios and [CII]158μm deficits compared to local galaxies. The origin of this behaviour is unknown. Numerous solutions have been proposed including differences in C and O abundance ratios, observational bias, and differences in ISM properties, including ionisati...

We investigate the evolution of the dark matter density profiles of the most massive galaxy clusters in the Universe. Using a ‘zoom-in’ procedure on a large suite of cosmological simulations of total comoving volume of 3 ( h ⁻¹ Gpc) ³ , we study the 25 most massive clusters in four redshift slices from z ~ 1 to the present. The minimum mass is M 50...

The implementation of ACACIA, a new algorithm to generate dark matter halo merger trees with the Adaptive Mesh Refinement code RAMSES, is presented. The algorithm is fully parallel and based on the Message Passing Interface. As opposed to most available merger tree tools, it works on the fly during the course of the N-body simulation. It can track...

We address the puzzling observational indications for very ‘cold’ galactic discs at redshifts z ≳ 3, an epoch when discs are expected to be highly perturbed. Using a high-resolution cosmological zoom-in simulation, we identify such a cold disc at z ∼ 3.5, with a rotation velocity to velocity dispersion ratio of vϕ/σr ≃ 5 for the total gas. It forms...

By means of high-resolution hydrodynamical, three-dimensional calculations with nested-meshes, we evaluate the eccentricity reached by a low-mass, luminous planet embedded in an inviscid disc with constant thermal diffusivity and subjected to thermal forces. We find that a cell size of at most 1/10th of the size of the region heated by the planet i...

By means of high resolution hydrodynamical, three-dimensional calculations with nested-meshes, we evaluate the eccentricity reached by a low-mass, luminous planet embedded in an inviscid disc with constant thermal diffusivity and subjected to thermal forces. We find that a cell size of at most one tenth of the size of the region heated by the plane...

Magnetic fields have been included in cosmological simulations of galaxy formation only recently, due to advances in numerical techniques and a better understanding of the galaxy formation physics. In this paper, we develop a new subgrid model for the turbulent dynamo that takes place in the supersonic interstellar medium in star-forming galaxies....

We implement EuclidEmulator (version 1), an emulator for the non-linear correction of the matter power spectrum, into the MCMC forecasting code MontePython. We compare the performance of Halofit, HMCode, and EuclidEmulator1, both at the level of power spectrum prediction and at the level of posterior probability distributions of the cosmological pa...

ALMA observations of $z>6$ galaxies have revealed abnormally high [OIII]$_{\rm 88\mu m}$/[CII]$_{\rm 158\mu m}$ ratios and [CII] deficits compared to local galaxies. The origin of this behaviour is unknown. Numerous solutions have been proposed including differences in C and O abundance ratios, observational bias, and differences in ISM properties,...

We present a suite of high-resolution cosmological zoom-in simulations to z = 4 of a 10¹² M_⊙ halo at z = 0, obtained using seven contemporary astrophysical simulation codes (Art-I, Enzo, Ramses, Changa, Gadget-3, Gear, and Gizmo) widely used in the numerical galaxy formation community. The physics prescriptions for gas cooling and heating and star...

We present the first results from SPHINX-MHD, a suite of cosmological radiation-magnetohydrodynamics simulations designed to study the impact of primordial magnetic fields (PMFs) on galaxy formation and the evolution of the intergalactic medium (IGM) during the epoch of reionization. The simulations are among the first to employ multi-frequency, on...

We present a novel set of stellar feedback models, implemented in the moving-mesh code Arepo, designed for galaxy formation simulations with near-parsec (or better) resolution. These include explicit sampling of stars from the IMF, allowing feedback to be linked to individual massive stars, an improved method for the modelling of H ii regions, phot...

We present a suite of high-resolution cosmological zoom-in simulations to $z=4$ of a $10^{12}\,{\rm M}_{\odot}$ halo at $z=0$, obtained using seven contemporary astrophysical simulation codes widely used in the numerical galaxy formation community. Physics prescriptions for gas cooling, heating, and star formation, are similar to the ones used in o...

We investigate the effect of the Biermann battery during the Epoch of reionization (EoR) using cosmological Adaptive Mesh Refinement simulations within the framework of the sphinx project. We develop a novel numerical technique to solve for the Biermann battery term in the Constrained Transport method, preserving both the zero divergence of the mag...

We study in this paper three variants of the high-order Discontinuous Galerkin (DG) method with Runge-Kutta (RK) time integration for the induction equation, analysing their ability to preserve the divergence-free constraint of the magnetic field. To quantify divergence errors, we use a norm based on both a surface term, measuring global divergence...

We address the puzzling observational indications for very "cold" galactic discs at redshifts $z \gtrsim 3$, an epoch when discs are expected to be highly perturbed. Using a high-resolution cosmological zoom-in simulation, we identify such a cold disc at $z\sim 3.5$, with a rotation velocity to velocity dispersion ratio of $v_\phi/\sigma_r \simeq 5...

We investigate the effect of the Biermann battery during the Epoch of Reionization (EoR) using cosmological Adaptive Mesh Refinement simulations within the framework of the SPHINX project. We develop a novel numerical technique to solve for the Biermann battery term in the Constrained Transport method, preserving both the zero divergence of the mag...

We present the first results from SPHINX-MHD, a suite of cosmological radiation-magnetohydrodynamics simulations designed to study the impact of primordial magnetic fields (PMFs) on galaxy formation and the evolution of the intergalactic medium during the epoch of reionization. The simulations are among the first to employ on-the-fly radiation tran...

Euclid, an ESA mission designed to characterise dark energy and dark matter, passed its Mission Critical Design Review in November 2018. It was demonstrated that the project is ready to start integration and test of the main systems, and that it has the ability to fulfil its top-level mission requirements. In addition, based on the performances at...

We introduce a new method to mitigate numerical diffusion in adaptive mesh refinement (AMR) simulations of cosmological galaxy formation, and study its impact on a simulated dwarf galaxy as part of the ‘EDGE’ project. The target galaxy has a maximum circular velocity of 21 km s−1 but evolves in a region which is moving at up to 90 km s−1 relative t...

The interplay of star formation and supernova (SN) feedback in galaxy formation is a key element for understanding galaxy evolution. Since these processes occur at small scales, it is necessary to have sub-grid models that recover their evolution and environmental effects at the scales reached by cosmological simulations. In this work, we present t...

We present a new, updated version of the EuclidEmulator (called EuclidEmulator2), a fast and accurate predictor for the nonlinear correction of the matter power spectrum. Percent-level accurate emulation is now supported in the eight-dimensional parameter space of $w_0w_a$CDM$+\sum m_\nu$models between redshift $z=0$ and $z=3$ for spatial scales wi...

We present a new, updated version of the EuclidEmulator (called EuclidEmulator2), a fast and accurate predictor for the nonlinear correction of the matter power spectrum. Percent-level accurate emulation is now supported in the eight-dimensional parameter space of w₀w_aCDM+∑m_ν models between redshift z = 0 and z = 3 for spatial scales within the r...

Galactic outflows driven by stellar feedback are crucial for explaining the inefficiency of star formation in galaxies. Although strong feedback can promote the formation of galactic discs by limiting star formation at early times and removing low angular momentum (AM) gas, it is not understood how the same feedback can result in diverse objects su...

We present a novel set of stellar feedback models, implemented in the moving-mesh code Arepo, designed for galaxy formation simulations with near-parsec (or better) resolution. These include explicit sampling of stars from the IMF, allowing feedback to be linked to individual massive stars, an improved method for the modelling of H II regions, phot...

We introduce a new method to mitigate numerical diffusion in adaptive mesh refinement (AMR) simulations of cosmological galaxy formation, and study its impact on a simulated dwarf galaxy as part of the 'EDGE' project. The target galaxy has a maximum circular velocity of 21 km/s but evolves in a region which is moving at up to 90 km/s relative to th...

Cosmic Dawn II yields the first statistically meaningful determination of the relative contribution to reionization by galaxies of different halo mass, from a fully coupled radiation-hydrodynamics simulation of the epoch of reionization large enough (∼100 Mpc) to model global reionization while resolving the formation of all galactic haloes above $...

Cosmic Dawn II (CoDa II) is a new, fully coupled radiation-hydrodynamics simulation of cosmic reionization and galaxy formation and their mutual impact, to redshift z < 6. With 40963 particles and cells in a 94 Mpc box, it is large enough to model global reionization and its feedback on galaxy formation while resolving all haloes above 108 M⊙. Usin...

We study in this paper three variants of the high-order Discontinuous Galerkin (DG) method with Runge-Kutta (RK) time integration for the induction equation, analysing their ability to preserve the divergence free constraint of the magnetic field. To quantify divergence errors, we use a norm based on both a surface term, measuring global divergence...

We use a recently introduced statistic called Integrated Bispectrum (IB) to probe the gravity-induced non-Gaussianity at the level of the bispectrum from weak lensing convergence or κ maps. We generalize the concept of the IB to spherical coordinates, {This result is next connected to the response function approach.} Finally, we use the Euclid Flag...

An accurate modelling of baryonic feedback effects is required to exploit the full potential of future weak-lensing surveys such as Euclid or LSST . In this second paper in a series of two, we combine Euclid-like mock data of the cosmic shear power spectrum with an eROSITA X-ray mock of the cluster gas fraction to run a combined likelihood analysis...

Baryonic feedback effects lead to a suppression of the weak lensing angular power spectrum on small scales. The poorly constrained shape and amplitude of this suppression is an important source of uncertainties for upcoming cosmological weak lensing surveys such as Euclid or LSST. In this first paper in a series of two, we use simulations to build...

The interplay of star formation and supernova (SN) feedback in galaxy formation is a key element for understanding galaxy evolution. Since these processes occur at small scales, it is necessary to have sub-grid models that recover their evolution and environmental effects at the scales reached by cosmological simulations. We simulate the same spira...

Stars in globular clusters (GCs) lose a non-negligible amount of mass during their post-main-sequence evolution. This material is then expected to build up a substantial intracluster medium (ICM) within the GC. However, the observed gas content in GCs is a couple of orders of magnitude below these expectations. Here, we follow the evolution of this...

Classical theories for the stellar initial mass function (IMF) predict a peak mass that scales with the properties of the molecular cloud. In this work, we explore a new theory proposed by Lee and Hennebelle. The idea is that the tidal field around first Larson cores prevents the formation of other collapsing clumps within a certain radius. The pro...

Galactic outflows driven by stellar feedback are crucial for explaining the inefficiency of galaxy formation. Although strong feedback can promote the formation of galactic discs by limiting star formation at early times and removing low angular momentum gas, it is not understood how the same feedback can result in diverse objects such as elliptica...

Regulating the available gas mass inside galaxies proceeds through a delicate balance between inflows and outflows, but also through the internal depletion of gas due to star formation. At the same time, stellar feedback is the internal engine that powers the strong outflows. Since star formation and stellar feedback are both small-scale phenomena,...

Stars in globular clusters (GCs) lose a non negligible amount of mass during their post-main sequence evolution. This material is then expected to build up a substantial intra-cluster medium (ICM) within the GC. However, the observed gas content in GCs is a couple of orders of magnitude below these expectations. Here we follow the evolution of this...

Cosmic Dawn ("CoDa") II yields the first statistically-meaningful determination of the relative contribution to reionization by galaxies of different halo mass, from a fully-coupled radiation-hydrodynamics simulation of the epoch of reionization large enough ($\sim 100$ Mpc) to model global reionization while resolving the formation of all galactic...

As part of the AGORA High-resolution Galaxy Simulations Comparison Project (Kim et al. 2014, 2016) we have generated a suite of isolated Milky Way-mass galaxy simulations using 9 state-of-the-art gravito-hydrodynamics codes widely used in the numerical galaxy formation community. In these simulations weadopted identical galactic disk initial condit...

We introduce the ‘Engineering Dwarfs at Galaxy Formation’s Edge’ (EDGE) project to study the cosmological formation and evolution of the smallest galaxies in the Universe. In this first paper, we explore the effects of resolution and sub-grid physics on a single low-mass halo (⁠M_{halo}=10^{9}M⊙⁠), simulated to redshift z = 0 at a mass and spatial...

The cold molecular gas in contemporary galaxies is structured in discrete cloud complexes. These giant molecular clouds (GMCs), with 10⁴–10⁷ solar masses (M⊙) and radii of 5–100 parsecs, are the seeds of star formation¹. Highlighting the molecular gas structure at such small scales in distant galaxies is observationally challenging. Only a handful...

An accurate modelling of baryonic feedback effects is required to exploit the full potential of future weak-lensing surveys such as Euclid or LSST. In this second paper in a series of two, we combine Euclid-like mock data of the cosmic shear power spectrum with an eROSITA X-ray mock of the cluster gas fraction to run a combined likelihood analysis...

Classical theories for the stellar initial mass function (IMF) predict a peak mass which scales with the properties of the molecular cloud. In this work, we explore a new theory proposed by Lee & Hennebelle (2018). The idea is that the tidal field around first Larson cores prevents the formation of other collapsing clumps within a certain radius. T...

Baryonic feedback effects lead to a suppression of the weak-lensing angular power spectrum on small scales. The poorly constrained shape and amplitude of this suppression is an important source of uncertainties for upcoming cosmological weak-lensing surveys such as Euclid or LSST. In this first paper in a series of two, we use simulations to build...

We simulate the flux emitted from galaxy haloes in order to quantify the brightness of the circumgalactic medium (CGM). We use dedicated zoom-in cosmological simulations with the hydrodynamical adaptive mesh refinement code RAMSES, which are evolved down to z = 0 and reach a maximum spatial resolution of 380 h⁻¹ pc and a gas mass resolution up to 1...

The cold molecular gas in contemporary galaxies is structured in discrete cloud complexes. These giant molecular clouds (GMCs), with $10^4$-$10^7$ solar masses and radii of 5-100 parsecs, are the seeds of star formation. Highlighting the molecular gas structure at such small scales in distant galaxies is observationally challenging. Only a handful...

We simulate the flux emitted from galaxy halos in order to quantify the brightness of the circumgalactic medium (CGM). We use dedicated zoom-in cosmological simulations with the hydrodynamical Adaptive Mesh Refinement code RAMSES, which are evolved down to z=0 and reach a maximum spatial resolution of 380 $h^{-1}$pc and a gas mass resolution up to...

We review the numerical techniques for ideal and non-ideal magneto-hydrodynamics (MHD) used in the context of star formation simulations. We outline the specific challenges offered by modeling star forming environments, which are dominated by supersonic and super-Alfvénic turbulence in a radiative, self-gravitating fluid. These conditions are rathe...

We review the numerical techniques for ideal and non-ideal magneto-hydrodynamics (MHD) used in the context of star formation simulations. We outline the specific challenges offered by modeling star forming environments, which are dominated by supersonic and super-Alfvenic turbulence in a radiative, self-gravitating fluid. These conditions are rathe...

Regulating the available gas mass inside galaxies proceeds through a delicate balance between inflows and outflows, but also through the internal depletion of gas due to star formation. At the same time, stellar feedback is the internal engine that powers the strong outflows. Since star formation and stellar feedback are both small scale phenomena,...

We present a new power spectrum emulator named EuclidEmulator that estimates the nonlinear correction to the linear dark matter power spectrum depending on the six cosmological parameters ' ‰ b, ' ‰ m, n s, h, w 0, and σ 8. It is constructed using the uncertainty quantification software UQLab using a spectral decomposition method called polynomial...

Dark matter dominates the properties of large cosmological structures such as galaxy clusters, and the mass profiles of the dark matter have been measured for these equilibrated structures for years using X-rays, lensing or galaxy velocities. A new method has been proposed, which should allow us to measure a dynamical property of the dark matter, n...

We introduce the "Engineering Dwarfs at Galaxy Formation's Edge" (EDGE) project to study the cosmological formation and evolution of the smallest galaxies in the Universe. In this first paper, we explore the effects of resolution and sub-grid physics on a single low mass halo ($M_{\rm halo}=10^{9}~M_\odot$), simulated to redshift $z=0$ at a mass an...