Size matters: abundance matching, galaxy sizes, and the Tully-Fisher relation in EAGLE

Abstract

The Tully-Fisher relation (TFR) links the stellar mass of a disk galaxy, $M_{\mathrm{str}}$, to its rotation speed: it is well approximated by a power law, shows little scatter, and evolves weakly with redshift. The relation has been interpreted as reflecting the mass-velocity scaling ($M\propto V^3$) of dark matter halos, but this interpretation has been called into question by abundance-matching (AM) models, which predict the galaxy-halo mass relation to be non-monotonic and rapidy evolving. We study the TFR of luminous spirals and its relation to AM using the EAGLE set of $\Lambda$CDM cosmological simulations. Matching both relations requires disk sizes to satisfy constraints given by the concentration of halos and their response to galaxy assembly. EAGLE galaxies approximately match these constraints and show a tight mass-velocity scaling that compares favourably with the observed TFR. The TFR is degenerate to changes in galaxy formation efficiency and the mass-size relation; simulations that fail to match the galaxy stellar mass function may fit the observed TFR if galaxies follow a different mass-size relation. The small scatter in the simulated TFR results because, at fixed halo mass, galaxy mass and rotation speed correlate strongly, scattering galaxies along the main relation. EAGLE galaxies evolve with lookback time following approximately the prescriptions of AM models and the observed mass-size relation of bright spirals, leading to a weak TFR evolution consistent with observation out to $z=1$. $\Lambda$CDM models that match both the abundance and size of galaxies as a function of stellar mass have no difficulty reproducing the observed TFR and its evolution.

12 pages, 7 figures, 1 table, submitted to MNRAS

References in corpus (12)

• The EAGLE project: Simulating the evolution and assembly of galaxies and their environments
• The EAGLE simulations of galaxy formation: calibration of subgrid physics and model variations
• 3D-HST+CANDELS: The Evolution of the Galaxy Size-Mass Distribution since $z=3$
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• The abundance of (not just) dark matter haloes
• On the baryonic, stellar, and luminous scaling relations of disk galaxies

Cited by in corpus (6)

• The Size Evolution of Star-forming and Quenched Galaxies in the IllustrisTNG simulation
• The KMOS Redshift One Spectroscopic Survey (KROSS): rotational velocities and angular momentum of z~0.9 galaxies
• Realistic simulations of galaxy formation in f(R) modified gravity
• Rotation curves and scaling relations of extremely massive spiral galaxies
• The vertical structure of gaseous galaxy discs in cold dark matter halos
• The angular momentum of disc galaxies at z=1