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The origin of scatter in the stellar mass-halo mass relation of central galaxies in the EAGLE simulation

Matthee, J and Schaye, J and Crain, RA and Schaller, M and Bower, R and Theuns, T (2017) The origin of scatter in the stellar mass-halo mass relation of central galaxies in the EAGLE simulation. Monthly Notices of the Royal Astronomical Society, 465 (2). pp. 2381-2884. ISSN 0035-8711

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Abstract

We use the hydrodynamical EAGLE simulation to study the magnitude and origin of the scatter in the stellar mass–halo mass relation for central galaxies.We separate cause and effect by correlating stellar masses in the baryonic simulation with halo properties in a matched dark matter only (DMO) simulation. The scatter in stellar mass increases with redshift and decreases with halomass. At z=0.1, it declines from 0.25 dex atM200,DMO ≈ 1011 M_ to 0.12 dex at M200,DMO ≈ 1013 M_, but the trend is weak above 1012 M_. For M200,DMO < 1012.5 M_ up to 0.04 dex of the scatter is due to scatter in the halo concentration. At fixed halo mass, a larger stellar mass corresponds to a more concentrated halo. This is likely because higher concentrations imply earlier formation times and hence more time for accretion and star formation, and/or because feedback is less efficient in haloes with higher binding energies. Themaximum circular velocity, Vmax, DMO, and binding energy are therefore more fundamental properties than halo mass, meaning that they are more accurate predictors of stellar mass, and we provide fitting formulae for their relations with stellar mass. However, concentration alone cannot explain the total scatter in the Mstar–M200,DMO relation, and it does not explain the scatter in Mstar–Vmax, DMO. Halo spin, sphericity, triaxiality, substructure and environment are also not responsible for the remaining scatter, which thus could be due to more complex halo properties or non-linear/stochastic baryonic effects.

Item Type: Article
Additional Information: This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society ©: The Authors 2016 Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.
Subjects: Q Science > QB Astronomy
Q Science > QC Physics
Divisions: Astrophysics Research Institute
Publisher: Oxford University Press
Date Deposited: 11 Jan 2017 09:29
Last Modified: 07 Sep 2017 13:23
DOI or Identification number: 10.1093/mnras/stw2884
URI: http://researchonline.ljmu.ac.uk/id/eprint/5226

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