The unexpected diversity of dwarf galaxy rotation curves

被引:323
|
作者
Oman, Kyle A. [1 ]
Navarro, Julio F. [1 ]
Fattahi, Azadeh [1 ]
Frenk, Carlos S. [2 ]
Sawala, Till [2 ]
White, Simon D. M. [3 ]
Bower, Richard [2 ]
Crain, Robert A. [4 ]
Furlong, Michelle [2 ]
Schaller, Matthieu [2 ]
Schaye, Joop [5 ]
Theuns, Tom [2 ]
机构
[1] Univ Victoria, Dept Phys & Astron, Victoria, BC V8P 5C2, Canada
[2] Univ Durham, Inst Computat Cosmol, Dept Phys, Durham DH1 3LE, England
[3] Max Planck Inst Astrophys, D-85748 Garching, Germany
[4] Liverpool John Moores Univ, Astrophys Res Inst, IC2, Liverpool L3 5RF, Merseyside, England
[5] Leiden Univ, Leiden Observ, NL-2300 RA Leiden, Netherlands
基金
美国国家科学基金会; 欧洲研究理事会; 英国科学技术设施理事会;
关键词
galaxies: haloes; galaxies: structure; dark matter; SURFACE BRIGHTNESS GALAXIES; DARK-MATTER HALOES; LAMBDA-CDM HALOES; MASS MODELS; DENSITY PROFILE; INNER STRUCTURE; CORES; STELLAR; SIMULATIONS; CONSTRAINTS;
D O I
10.1093/mnras/stv1504
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
We examine the circular velocity profiles of galaxies in Lambda cold dark matter (CDM) cosmological hydrodynamical simulations from the EAGLE and LOCAL GROUPS projects and compare them with a compilation of observed rotation curves of galaxies spanning a wide range in mass. The shape of the circular velocity profiles of simulated galaxies varies systematically as a function of galaxy mass, but shows remarkably little variation at fixed maximum circular velocity. This is especially true for low-mass dark-matter-dominated systems, reflecting the expected similarity of the underlying CDM haloes. This is at odds with observed dwarf galaxies, which show a large diversity of rotation curve shapes, even at fixed maximum rotation speed. Some dwarfs have rotation curves that agree well with simulations, others do not. The latter are systems where the inferred mass enclosed in the inner regions is much lower than expected for CDM haloes and include many galaxies where previous work claims the presence of a constant density 'core'. The 'cusp versus core' issue is thus better characterized as an 'inner mass deficit' problem than as a density slope mismatch. For several galaxies, the magnitude of this inner mass deficit is well in excess of that reported in recent simulations where cores result from baryon-induced fluctuations in the gravitational potential. We conclude that one or more of the following statements must be true: (i) the dark matter is more complex than envisaged by any current model; (ii) current simulations fail to reproduce the diversity in the effects of baryons on the inner regions of dwarf galaxies; and/or (iii) the mass profiles of 'inner mass deficit' galaxies inferred from kinematic data are incorrect.
引用
收藏
页码:3650 / 3665
页数:16
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