The kinematics and dark matter fractions of TNG50 galaxies at z=2 from an observational perspective

Uebler, Hannah; Genel, Shy; Sternberg, Amiel; Genzel, Reinhard; Price, Sedona H.; Schreiber, Natascha M. Foerster; Shimizu, Taro T.; Pillepich, Annalisa; Nelson, Dylan; Burkert, Andreas; Davies, Ric; Hernquist, Lars; Lang, Philipp; Lutz, Dieter; Pakmor, Rudiger und Tacconi, Linda J. (2021): The kinematics and dark matter fractions of TNG50 galaxies at z=2 from an observational perspective. In: Monthly Notices of the Royal Astronomical Society, Bd. 500, Nr. 4: S. 4597-4619

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-* > 4 x 10(10) M-circle dot, SFR >50 M-circle dot 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 modelling 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 1D 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(DM)(v) (< R e ) = v(DM)(2)(R-e)/v(circ)(2)(R-e) similar to 0.32 +/- 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 similar to 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.

• Dokumententyp: Zeitschriftenartikel
• Fakultät: Physik
• Themengebiete: 500 Naturwissenschaften und Mathematik > 530 Physik
• ISSN: 0035-8711
• Sprache: Englisch