Evaluating the ability of triaxial Schwarzschild modelling to estimate properties of galaxies from the Illustris simulation

Autor(en)
Yunpeng Jin, Ling Zhu, R. J. Long, Shude Mao, Dandan Xu, Hongyu Li, Glenn van de Ven
Abstrakt

We evaluate the capabilities of Schwarzschild's orbit-superposition

method by applying it to galaxies from the large scale, high resolution

Illustris simulation. Nine early-type galaxies with a range of

triaxiality are selected, and we create mock integral field unit data

for five line-of-sight projections of each galaxy. Each of the 45 mock

data sets is taken as an independent observed galaxy. Using van den

Bosch's 2008 triaxial Schwarzschild implementation, we assess model

estimates of various galaxy properties, covering mass profiles,

intrinsic shapes, stellar orbit distributions and velocity anisotropies.

Total mass within \overline{R_e} is recovered well with average

deviations within ±15 percent. Stellar mass is underestimated by

˜24 percent and dark matter overestimated by ˜38 percent

(assuming an NFW dark matter profile and allowing for degeneracy between

stellar mass and dark matter mass). Using a gNFW profile, these values

improve to ˜13 percent for stellar mass and ˜18 percent for

dark matter. Axis ratio estimates show a moderate bias of Δ(b/a) =

0.07 and Δ(c/a) = 0.14 (a ≥ b ≥ c). Distributions of the

orbit circularities λz and λx,

representing rotation about the minor and major axes, are well

reconstructed. Separating orbits into thermal categories, our models

match the average fractions of these categories to within 10 percent.

Velocity anisotropy is well estimated with values matching in the inner

regions but becoming slightly radially biased in the outer regions.

Overall, the galaxy property estimates we obtained using Schwarzschild

modelling are not implausible and are representative of the simulated

galaxies we modelled.

Organisation(en)
Institut für Astrophysik
Journal
Monthly Notices of the Royal Astronomical Society
Band
486
Seiten
4753–4772
ISSN
0035-8711
DOI
https://doi.org/10.1093/mnras/stz1170
Publikationsdatum
04-2019
Publikationsstatus
Elektronische Veröffentlichung vor Drucklegung
Peer-reviewed
Ja
ÖFOS 2012
103003 Astronomie, 103004 Astrophysik
Link zum Portal
https://ucris.univie.ac.at/portal/de/publications/evaluating-the-ability-of-triaxial-schwarzschild-modelling-to-estimate-properties-of-galaxies-from-the-illustris-simulation(164c2b01-cee1-40ee-89d2-cf4b2d343b4b).html