Redshift evolution of the Fundamental Plane relation in the IllustrisTNG simulation. Issue 4 (28th January 2020)

• Record Type: Journal Article
• Authors: Lu, Shengdong; Xu, Dandan; Wang, Yunchong; Mao, Shude; Ge, Junqiang; Springel, Volker; Wang, Yuan; Vogelsberger, Mark; Naiman, Jill; Hernquist, Lars
• Is Part Of: Monthly notices of the Royal Astronomical Society. Volume 492:Issue 4(2020)
• Page Start: 5930
• Page End: 5939
• Publication Date: 2020-01-28
• Subjects: methods: numerical -- galaxies: elliptical and lenticular, cD -- galaxy: evolution -- galaxies: formation -- galaxy: kinematics and dynamics; Astronomy -- Periodicals; Periodicals; 520.5
• DOI: 10.1093/mnras/staa173
• Languages: English
• ISSNs: 0035-8711

Abstract

ABSTRACT: We investigate the Fundamental Plane (FP) evolution of early-type galaxies in the IllustrisTNG-100 simulation (TNG100) from redshift z = 0 to z = 2. We find that a tight plane relation already exists as early as z = 2. Its scatter stays as low as ∼0.08 dex across this redshift range. Both slope parameters b and c (where R ∝ σ b I c with R, σ, and I being the typical size, velocity dispersion, and surface brightness) of the plane evolve mildly since z = 2, roughly consistent with observations. The FP residual $\rm Res$ ($\equiv \, a\, +\, b\log \sigma \, +\, c\log I\, -\, \log R$, where a is the zero-point of the FP) is found to strongly correlate with stellar age, indicating that stellar age can be used as a crucial fourth parameter of the FP. However, we find that 4 c + b + 2 = δ, where δ ∼ 0.8 for FPs in TNG, rather than zero as is typically inferred from observations. This implies that a tight power-law relation between the dynamical mass-to-light ratio M dyn / L and the dynamical mass M dyn (where M dyn ≡ 5σ 2 R / G, with G being the gravitational constant) is not present in the TNG100 simulation. Recovering such a relation requires proper mixing between dark matter and baryons, as well as star formation occurring with correct efficiencies at the right mass scales. This represents a powerful constraint on the numerical models, which has to be satisfied in future hydrodynamical simulations.