Probing the Low Surface Brightness Universe with Dragonfly

用蜻蜓号探测低表面亮度宇宙

• 批准号: DGDND-2017-00012
• 负责人: Abraham, Roberto
• 金额: $ 2.91万
• 依托单位: University of Toronto
• 依托单位国家: 加拿大
• 项目类别: DND/NSERC Discovery Grant Supplement
• 财政年份: 2017
• 资助国家: 加拿大
• 起止时间: 2017-01-01 至 2018-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=617736
• 关键词: Probing; Low; Surface; Brightness; Universe

Over the past 40 years the cutting edge of astronomical imaging has transitioned from photographic plates on ground based telescopes to CCD detectors on space telescopes. This has improved our ability to detect small faint galaxies by about seven magnitudes (over a factor of 600). Over this same period of time there has been no improvement in our ability to detect large but faint (low surface brightness) structures in the Universe. This is because the limiting factor in this case is not photon statistics or image resolution, it is control of systematic errors, such as the scattering of light and sky variability. Working with a colleague at Yale, I recently developed a novel new telescope, the Dragonfly Telephoto Array, which has succeeded in breaking through this technical barrier and which is revealing the composition of the Universe at very faint surface brightness levels (Abraham & van Dokkum 2014). This is an area of astronomy that is almost totally unexplored, and in the last two years we have used this telescope (constructed from an array of high-end commercial telephoto lenses) to probe the Universe down to hitherto impossibly faint surface brightness levels. A number of remarkable discoveries have been made, most notably the existence of a new population of giant but faint galaxies that preferentially inhabit rich galaxy clusters. These "ultra-diffuse galaxies" are as big as the Milky Way but have only 1/100 – 1/1000 of its mass, and explaining how they survive in the very hostile environment of a galaxy cluster is a major puzzle that has become a highly active area of investigation in the last year. But these early results from Dragonfly are only the tip of the iceberg. It is now clear that the low surface brightness Universe is a treasure trove of almost totally unexplored astrophysical phenomena, and the race is now on to study these. In this proposal I describe a program of investigation whose goals are to: (1) explore the nature of dark matter in ultra-diffuse galaxies by determining their masses in galactic stellar halos; (2) test fundamental predictions of models for galaxy assembly by undertaking an ambitious wide-area survey of the low surface brightness sky; (3) determine the ultimate limits for the performance of the Dragonfly concept, in order to see if we can grow the system to the point that we can directly explore the "cosmic web"– a predicted large-scale network of dark matter filaments believed to connect galaxies to each other.

在过去的40年中，天文成像的尖端已从地面望远镜上的摄影板转变为太空望远镜上的CCD探测器。这提高了我们检测到小的微弱星系的能力，大约有七个磁化率（超过600倍）。在同一时期，我们检测到宇宙中大但新鲜（低表面亮度）结构的能力没有改善。这是因为在这种情况下的限制因素不是光子统计或图像分辨率，而是对系统误差的控制，例如光和天空变异性的散射。与耶鲁大学的一位同事合作，我最近开发了一种新颖的新望远镜，蜻蜓远摄阵列，该阵列阵列成功地突破了这一技术障碍，并在非常微弱的表面亮度水平上揭示了宇宙的组成（Abraham＆van Dokkum 2014）。这是一个几乎完全出乎意料的天文学领域，在过去的两年中，我们使用了该望远镜（由一系列高端商业远摄镜头构建）将宇宙探测到迄今为止迄今为止微弱的表面亮度水平。已经发现了许多杰出的发现，最值得注意的是，存在新的巨大但微弱的星系，这些星系优先居住在丰富的星系簇中。这些“超湿星系”与银河系一样大，但只有1/100 - 1/1000的质量，并解释它们如何在星系集群非常敌对的环境中生存，这是一个主要难题，它已成为去年高度活跃的投资领域。但是，蜻蜓的早期结果只是冰山一角。现在很明显，低表面亮度宇宙是几乎完全出乎意料的天体物理现象的宝库，现在种族正在研究这些现象。在此提案中，我描述了一项投资计划，该计划的目标是：（1）通过确定其在银河恒星光环中的质量来探索超湿星系中暗物质的性质； （2）通过对低表面亮度天空进行雄心勃勃的大区域调查，测试星系组件模型的基本预测； （3）确定蜻蜓概念表现的最终限制，以查看我们是否可以将系统发展到可以直接探索“宇宙网络”的地步，这是一个预测的大规模的暗物质细丝网络，被认为可以将星系连接到对方。