The inner structure of early-type galaxies in the Illustris simulation
Name
1610.07605.pdf
Description
Accepted version
Size
1.14 MB
Format
Adobe PDF
Checksum (MD5)
15ca61775fdcd0344ec0fbd39253fd51
Author(s)
Xu, Dandan
Springel, Volker
Sluse, Dominique
Schneider, Peter
Sonnenfeld, Alessandro
Nelson, Dylan
Vogelsberger, Mark
Hernquist, Lars
Date Issued
2017
Journal
Monthly Notices of the Royal Astronomical Society
Publisher
Oxford University Press (OUP)
Version
Author's final manuscript
Abstract
© 2017 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society Early-type galaxies provide unique tests for the predictions of the cold dark matter cosmology and the baryonic physics assumptions entering models for galaxy formation. In this work, we use the Illustris simulation to study correlations of three main properties of early-type galaxies, namely the stellar orbital anisotropies, the central dark matter fractions and the central radial density slopes, as well as their redshift evolution since z = 1.0. We find that lower mass galaxies or galaxies at higher redshift tend to be bluer in rest-frame colour, have higher central gas fractions, and feature more tangentially anisotropic orbits and steeper central density slopes than their higher mass or lower redshift counterparts, respectively. The projected central dark matter fraction within the effective radius shows a very mild mass dependence but positively correlates with galaxy effective radii due to the aperture effect. The central density slopes obtained by combining strong lensing measurements with single-aperture kinematics are found to differ from the true density slopes. We identify systematic biases in this measurement to be due to two common modelling assumptions, isotropic stellar orbital distributions and power-law density profiles. We also compare the properties of early-type galaxies in Illustris to those from existing galaxy and strong lensing surveys; we find in general broad agreement but also some tension, which poses a potential challenge to the stellar formation and feedback models adopted by the simulation.
MIT Department
Massachusetts Institute of Technology. Department of Physics
Terms of Use
Creative Commons Attribution-Noncommercial-Share Alike
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DOI of Published Version
https://doi.org/10.1093/MNRAS/STX899
