暗物质量匮乏星系NGC1052-DF2的距离
摘要
我们近期推断星系NGC1052-DF2几乎不含或不含暗物质,并拥有丰富的特殊球状星团系统。我们假定该星系是~20 Mpc处发光椭圆星系NGC1052的卫星,依据为其表面亮度涨落(SBF)距离 Mpc、约1800 km/s的径向速度及其投影位置。此处我们分析NGC1052-DF2的颜色-星等图(CMD),遵循Trujillo等人(2018)的建议,即当前可用HST数据中可探测红巨星支顶端(TRGB)且该星系位于~13 Mpc。利用充分填充的星系模型,我们表明CMD受混合像严重影响。这些混合像产生比真实TRGB亮约2倍的“幻影”TRGB,可导致比实际距离小约1.4倍的误差距离估计。我们将NGC1052-DF2与模型图像及我们HST样本中的其他星系比较,显示~13 Mpc距离预期的大量未混合RGB星未被探测到。我们还通过将其锚定到巨脉泽宿主星系NGC4258的卫星,提供了无定标不确定性的NGC1052-DF2新距离测量。由巨脉泽-TRGB-SBF距离阶梯我们得到 Mpc,与我们先前测量及椭圆星系NGC1052的距离一致。
引用
@article{arxiv.1807.06025,
title = {The Distance of the Dark Matter Deficient Galaxy NGC1052-DF2},
author = {Pieter van Dokkum and Shany Danieli and Yotam Cohen and Aaron Romanowsky and Charlie Conroy},
journal= {arXiv preprint arXiv:1807.06025},
year = {2018}
}
备注
Accepted for publication in ApJ Letters. The key point of the paper is made in Figure 2. All data and models are available upon request. Minor changes compared to V1 make the paper more of a stand-alone analysis and less of a response to Trujillo et al. (2018). Also see the independent analysis of Blakeslee & Cantiello (arXiv:1808.02176)