The central dark matter content of early-type galaxies: scaling relations and connections with star formation histories

被引:100
作者
Napolitano, Nicola R. [1 ]
Romanowsky, Aaron J. [2 ]
Tortora, Crescenzo [3 ,4 ]
机构
[1] Osserv Astron Capodimonte, INAF, I-80131 Naples, Italy
[2] Univ Calif Santa Cruz, UCO Lick Observ, Santa Cruz, CA 95064 USA
[3] Univ Zurich, Inst Theoret Phys, CH-8057 Zurich, Switzerland
[4] Univ Napoli Federico II, Dipartimento Sci Fisiche, I-80126 Naples, Italy
基金
瑞士国家科学基金会; 美国国家科学基金会;
关键词
galaxies: elliptical and lenticular; cD; galaxies: evolution; galaxies: fundamental parameters; dark matter; INITIAL MASS FUNCTION; TO-LIGHT RATIOS; SUPERMASSIVE BLACK-HOLE; LAMBDA-CDM UNIVERSE; LENS ACS SURVEY; FUNDAMENTAL PLANE; ELLIPTIC GALAXIES; STELLAR MASS; GLOBULAR-CLUSTERS; ROTATION CURVES;
D O I
10.1111/j.1365-2966.2010.16710.x
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
We examine correlations between masses, sizes and star formation histories for a large sample of low-redshift early-type galaxies, using a simple suite of dynamical and stellar population models. We confirm an anticorrelation between the size and stellar age and go on to survey for trends with the central content of dark matter (DM). An average relation between the central DM density and galaxy size of <<(DM)>> proportional to R-2(eff) provides the first clear indication of cuspy DM haloes in these galaxies - akin to standard Lambda cold dark matter haloes that have undergone adiabatic contraction. The DM density scales with galaxy mass as expected, deviating from suggestions of a universal halo profile for dwarf and late-type galaxies. We introduce a new fundamental constraint on galaxy formation by finding that the central DM fraction decreases with stellar age. This result is only partially explained by the size-age dependencies, and the residual trend is in the opposite direction to basic DM halo expectations. Therefore, we suggest that there may be a connection between age and halo contraction and that galaxies forming earlier had stronger baryonic feedback, which expanded their haloes, or lumpier baryonic accretion, which avoided halo contraction. An alternative explanation is a lighter initial mass function for older stellar populations.
引用
收藏
页码:2351 / 2371
页数:21
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