Planetary nebulae (PNe) may be the most promising tracers in the halos ofearly-type galaxies. We have used multi-object spectrographs on the WHT and theVLT, and the new Planetary Nebula Spectrograph on the WHT, to obtain hundredsof PN velocities in a small sample of nearby galaxies. These ellipticals showweak halo rotation, which may be consistent with ab initio models of galaxyformation, but not with more detailed major merger simulations. The galaxiesnear L* show evidence of a universal declining velocity dispersion profile, anddynamical models indicate the presence of little dark matter within 5 Reff --implying halos either not as massive or not as centrally concentrated as CDMpredicts.
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机译：行星状星云（PNe）可能是早期星系光环中最有前途的示踪剂。我们已经在WHT和VLT上使用了多对象光谱仪，并且在WHT上使用了新的行星状星云光谱仪，从而在附近星系的一小部分中获得了数百个PN速度。这些椭圆形显示出弱的晕轮旋转，这可能与星系从头算模型一致，但与更详细的主要合并模拟却不一致。 L *附近的星系显示出普遍的速度色散分布下降的证据，动力学模型表明5 Reff内几乎没有暗物质的存在-这意味着光环不像CDM预测的那么大或不集中。
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