The Kinematics and Dark Matter Fractions of TNG50 Galaxies at z=2 from an Observational Perspective

Abstract

We contrast the gas kinematics and dark matter contents of $z=2$ star-forming galaxies (SFGs) from state-of-the-art cosmological simulations within the $\Lambda$CDM framework to observations. To this end, we create realistic mock observations of massive SFGs ($M_{\ast }>4\times 10^{10}{M}_{\odot }$, SFR $>50M_{\odot }$ yr${}^{-1}$) from the TNG50 simulation of the IllustrisTNG suite, resembling near-infrared, adaptive-optics assisted integral-field observations from the ground. Using observational line fitting and modeling techniques, we analyse in detail the kinematics of seven TNG50 galaxies from five different projections per galaxy, and compare them to observations of twelve massive SFGs by Genzel et al. (2020). The simulated galaxies show clear signs of disc rotation but mostly exhibit more asymmetric rotation curves, partly due to large intrinsic radial and vertical velocity components. At identical inclination angle, their one-dimensional velocity profiles can vary along different lines of sight by up to $\Delta v=200$ km s${}^{-1}$. From dynamical modelling we infer rotation speeds and velocity dispersions that are broadly consistent with observational results. We find low central dark matter fractions compatible with observations ($f_{\mathrm{DM}}^v(<R_e)=v_{\mathrm{DM}}^2(R_e)/v_{\mathrm{circ}}^2(R_e)\sim 0.32\pm 0.10$), however for disc effective radii $R_e$ that are mostly too small: at fixed $R_e$ the TNG50 dark matter fractions are too high by a factor of $\sim 2$. We speculate that the differences in gas kinematics and dark matter content compared to the observations may be due to physical processes that are not resolved in sufficient detail with the numerical resolution available in current cosmological simulations.

25 pages, 16 figures, accepted for publication in MNRAS

References in corpus (32)

• A Highly Consistent Framework for the Evolution of the Star-Forming "Main Sequence" from z~0-6
• 3D-HST+CANDELS: The Evolution of the Galaxy Size-Mass Distribution since $z=3$
• Simulating galaxy formation with black hole driven thermal and kinetic feedback
• 3D-HST WFC3-selected Photometric Catalogs in the Five CANDELS/3D-HST Fields: Photometry, Photometric Redshifts and Stellar Masses
• High-Resolution Rotation Curves and Galaxy Mass Models from THINGS
• Constraining the Low-Mass Slope of the Star Formation Sequence at 0.5<z<2.5
• From rings to bulges: evidence for rapid secular galaxy evolution at z~2 from integral field spectroscopy in the SINS survey
• Combined CO & Dust Scaling Relations of Depletion Time and Molecular Gas Fractions with Cosmic Time, Specific Star Formation Rate and Stellar Mass
• Ubiquitous outflows in DEEP2 spectra of star-forming galaxies at z=1.4
• The KMOS^3D Survey: design, first results, and the evolution of galaxy kinematics from 0.7<z<2.7
• The Size Evolution of Star-forming and Quenched Galaxies in the IllustrisTNG simulation
• Strongly baryon-dominated disk galaxies at the peak of galaxy formation ten billion years ago
• Evidence for Wide-Spread AGN Driven Outflows in the Most Massive z~1-2 Star Forming Galaxies
• Geometry of Star-Forming Galaxies from SDSS, 3D-HST and CANDELS
• The mass distribution in early-type disk galaxies: declining rotation curves and correlations with optical properties
• The KMOS^3D Survey: data release and final survey paper
• Kinematic modelling of disk galaxies I. A new method to fit tilted rings to data cubes
• z~2: An Epoch of Disk Assembly
• LITTLE THINGS in 3D: robust determination of the circular velocity of dwarf irregular galaxies
• PHIBSS2: survey design and z=0.5-0.8 results. Molecular gas reservoirs during the winding-down of star formation
• Rotation Curves in z~1-2 Star-Forming Disks: Evidence for Cored Dark Matter Distributions
• The shape of the dark matter halo in the early-type galaxy NGC 2974
• Reconciling the observed star-forming sequence with the observed stellar mass function
• Structural evolution in massive galaxies at z~2
• The SINS/zC-SINF Survey of z~2 Galaxy Kinematics: Rest-frame Morphology, Structure, and Colors from Near-infrared Hubble Space Telescope Imaging
• Distinguishing Mergers and Disks in High Redshift Observations of Galaxy Kinematics
• The regulation of galaxy growth along the size-mass relation by star-formation, as traced by H$\alpha$ in KMOS${}^{3D}$ galaxies at 0.7 < z < 2.7
• On the Global Mass Distribution in Disk Galaxies
• The rotation curves of flattened Sersic bulges
• Recalibrating the Cosmic Star Formation History
• The kinematics of massive quiescent galaxies at $1.4<z<2.1$: dark matter fractions, IMF variation, and the relation to local early-type galaxies
• Massive disc galaxies in cosmological hydrodynamical simulations are too dark matter-dominated

Cited by in corpus (22)

• Systematic difference between ionized and molecular gas velocity dispersion in $z\sim 1-2$ disks and local analogues
• RC100: Rotation Curves of 100 Massive Star-Forming Galaxies at z=0.6-2.5 Reveal Little Dark Matter on Galactic Scales
• The MUSE Extremely Deep Field: Evidence for SFR-induced cores in dark-matter dominated galaxies at z=1
• Massive Black Hole Binaries from the TNG50-3 Simulation: I. Coalescence and LISA Detection Rates
• Probing the $z\gtrsim 6$ quasars in a universe with IllustrisTNG physics: Impact of gas-based black hole seeding models
• Gas Accretion Can Drive Turbulence in Galaxies
• KURVS: The outer rotation curve shapes and dark matter fractions of $z\sim 1.5$ star-forming galaxies
• The dawn of disks: unveiling the turbulent ionised gas kinematics of the galaxy population at $z\sim 4-6$ with JWST/NIRCam grism spectroscopy
• A ~600 pc view of the strongly-lensed, massive main sequence galaxy J0901: a baryon-dominated, thick turbulent rotating disk with a clumpy cold gas ring at z = 2.259
• The Response of Dark Matter Haloes to Gas Ejection: CuspCore II
• MUSE-ALMA Halos VI: Coupling Atomic, Ionised & Molecular Gas Kinematics of Galaxies
• Impact of gas based seeding on supermassive black hole populations at $z\ge 7$
• Kinematics and Mass Distributions for Non-Spherical Deprojected Sérsic Density Profiles and Applications to Multi-Component Galactic Systems
• The ALMA-CRISTAL survey: Resolved kinematic studies of main sequence star-forming galaxies at 4<z<6
• A large-scale kinematic study of molecular gas in high-z cluster galaxies: Evidence for high levels of kinematic asymmetry
• Dark matter cores in massive high-$z$ galaxies formed by baryonic clumps
• The Baltimore Oriole's Nest: Cool Winds from the Inner and Outer Parts of a Star-Forming Galaxy at z=1.3
• The dark side of early galaxies: $\text{geko}$ uncovers dark-matter fractions at $z\sim 4-6$
• The effects of environment on galaxies' dynamical structures: From simulations to observations
• Observational biases on rotation curves from IFU data at cosmic noon
• Diverse Rotation Curves of Galaxies in a Simulated Universe: the Observed Dependence on Stellar Mass and Morphology Reproduced
• Rotation Curves in z~1-2 Star-Forming Disks: Comparison of Dark Matter Fractions and Disk Properties for Different Fitting Methods