Shape, alignment, and mass distribution of baryonic and dark-matter halos in one EAGLE simulation

Abstract

Accurate knowledge of the morphology of halos and its evolution are key constraints on the galaxy formation model as well as a determinant parameter of the strong-lensing phenomenon. Using the cosmological hydrodynamic simulation, the Evolution and Assembly of GaLaxies and their Environments (EAGLE), we aim to provide a comprehensive analysis of the evolution of the morphology of galaxy halos and of their mass distributions with a focus on the snapshot at redshift $z=0.5$. We developed an iterative strategy involving a principal component analysis (PCA) to investigate the properties of the EAGLE halos and the differences in alignment between the various components. The mass distributions of the dark-matter (DM), gas, and star halos are characterised by a half-mass radius, a concentration parameter and (projected) axis ratios. We present statistics of the shape parameters of 336\,540 halos from the EAGLE RefL0025N0376 simulation and describe their evolution from redshift $z=15$ to $z=0$. We measured the three-dimensional and two-dimensional projected shape parameters for the DM, the gas, and the star components as well as for all particles. At $z=0.5$, the minor axis of gas aligns with the minor axis of DM for massive halos ($M>10^{12}$ M${}_{\odot }$), but this alignment is poorer for less massive halos. The DM halos axis ratios $b/a$ and $c/a$ have median values of $0.82\pm 0.11$ and $0.64\pm 0.12$, respectively. The sphericity of gas in halos w/ and w/o stars appears to be negatively correlated to the total mass, while the sphericity of DM is insensitive to it. The measured projected axis ratios, $b_p/a_p$, of star halos at $z=0.5$ have a median value of $0.80\pm 0.07$, which is in good agreement with ground-based and space-based measurements within 1 $\sigma$. For DM halos, we measure a value of $0.85\pm 0.06$.

arXiv comment19 pages, 24 Figures, 2 Tables, 1 Appendix

References in corpus (45)

• Planck 2013 results. XVI. Cosmological parameters
• The EAGLE project: Simulating the evolution and assembly of galaxies and their environments
• Populating a cluster of galaxies - I. Results at z=0
• Modeling feedback from stars and black holes in galaxy mergers
• The 3D power spectrum of galaxies from the SDSS
• The EAGLE simulations of galaxy formation: calibration of subgrid physics and model variations
• The Sixteenth Data Release of the Sloan Digital Sky Surveys: First Release from the APOGEE-2 Southern Survey and Full Release of eBOSS Spectra
• How Filaments are Woven into the Cosmic Web
• Substructures in hydrodynamical cluster simulations
• The Dark Energy Survey: more than dark energy - an overview
• The effect of photo-ionization on the cooling rates of enriched, astrophysical plasmas
• First Results from the TNG50 Simulation: The evolution of stellar and gaseous disks across cosmic time
• The Relationship Between Stellar Light Distributions of Galaxies and their Formation Histories
• Cosmological simulations of the growth of supermassive black holes and feedback from active galactic nuclei: method and tests
• Chemical enrichment in cosmological, smoothed particle hydrodynamics simulations
• On the relation between the Schmidt and Kennicutt-Schmidt star formation laws and its implications for numerical simulations
• Star formation thresholds and galaxy edges: why and where
• The Shape of Dark Matter Halos: Dependence on Mass, Redshift, Radius, and Formation
• Simulating galactic outflows with thermal supernova feedback
• The EAGLE simulations of galaxy formation: public release of halo and galaxy catalogues
• Chemical yields from low- and intermediate-mass stars: model predictions and basic observational constraints
• The MassiveBlack-II Simulation: The Evolution of Halos and Galaxies to z~0
• The impact of angular momentum on black hole accretion rates in simulations of galaxy formation
• A chronicle of galaxy mass assembly in the EAGLE simulation
• Galaxy alignments: Observations and impact on cosmology
• The impact of baryons on the spins and shapes of dark matter haloes
• The alignment and shape of dark matter, stellar, and hot gas distributions in the EAGLE and cosmo-OWLS simulations
• Galaxy Shapes and Intrinsic Alignments in The MassiveBlack-II Simulation
• The SWELLS survey. IV. Precision measurements of the stellar and dark matter distributions in a spiral lens galaxy
• Gaia Data Release 3: The extragalactic content
• Probing the Intrinsic Shape and Alignment of Dark Matter Haloes using SDSS Galaxy Groups
• The relationship between the morphology and kinematics of galaxies and its dependence on dark matter halo structure in EAGLE
• Constraints on the shapes of galaxy dark matter haloes from weak gravitational lensing
• Alignments between galaxies, satellite systems and haloes
• What Makes the Family of Barred Disc Galaxies So Rich: Damping Stellar Bars in Spinning Haloes
• Gaia GraL: Gaia DR2 Gravitational Lens Systems. III. A systematic blind search for new lensed systems
• Two-dimensional galaxy-galaxy lensing: a direct measure of the flattening and alignment of light and mass in galaxies
• Gaia GraL: Gaia DR2 Gravitational Lens Systems. VI. Spectroscopic Confirmation and Modeling of Quadruply-Imaged Lensed Quasars
• Using Quadruple Lenses to probe the Structure of the Lensing Galaxy
• Dark Matter Bars in Spinning Halos
• Numerical Simulations Unravel the Cosmic Web
• The Effect of Dark Matter Halo Shape on Bar Buckling and Boxy/Peanut Bulges
• Galaxy-lens determination of $H_0$: the effect of the ellipse+shear modeling assumption
• Model-free analysis of quadruply imaged gravitationally lensed systems and substructured galaxies
• The morphology of star-forming gas and its alignment with galaxies and dark matter haloes in the EAGLE simulations