The Dragonfly Project: Imaging the outer limits of nearby galaxies

星系形成的模拟一般预测，所有明亮的星系都嵌入在广泛的潮汐碎片场，造成偶尔的重大合并和小卫星星系的持续吸积。 奇怪的是，这些碎片场在实际的星系周围消失了。 虽然这可能表明需要对标准宇宙学进行修订，但一个更普通的解释是，我们还没有获得足够深入的观测来探测碎片场。 该奖项为蜻蜓项目提供支持，该项目将尝试进行此类检测。 该项目是一个超低表面亮度成像调查与蜻蜓望远镜的所有发光星系的距离内30兆秒差距（Mpc），是从新墨西哥州可见。 在为期3年的奖励期内，研究人员将获得72个明亮的邻近星系的完整样本的40小时深度图像，最近的模拟表明，这些碎片大部分存在于29至31等/角秒^[2]的表面亮度下，比典型的深度成像极限（约28等/角秒^[2]）要暗。 研究人员建造了一台望远镜，专门用于确定是否所有星系周围都有30- 100千秒差距尺度的超低表面亮度潮汐碎片。 在3角秒尺度上，收集到的数据将达到每角秒约30等^[2]。 蜻蜓望远镜是一个与标准电荷耦合器件（CCD）成像器相结合的长焦镜头阵列。 最新一代的这些镜头具有纳米制造的涂层，最大限度地减少散射和反射光。 这些透镜一起构成了一个完美的挡板望远镜，具有极快的全折射光学系统和比现有反射望远镜更好的散射光控制（数量级）。研究小组将通过网络界面公开完全处理和校准的图像。 该项目以下列方式将教育和研究结合起来：（1）该项目是对多年来在大型望远镜上进行的仪器测量工作的补充，非常适合于天体物理仪器测量方面的研究生培训。(2)简单的远程操作模型非常适合课堂教学和演示。 该望远镜将被纳入耶鲁大学的本科生和研究生课程，也将被用作高中生的科学演示工具。

Simulations of galaxy formation generically predict that all luminous galaxies are embedded in extensive tidal debris fields, caused by occasional major mergers and the continuous accretion of small satellite galaxies. These debris fields are curiously missing around actual galaxies. While this may indicate that revisions to the standard cosmology are needed, a more mundane explanation is that we have not yet obtained sufficiently deep observations to detect the debris fields. This award provides support for the Dragonfly Project that will attempt such a detection. The project is an ultra low surface brightness imaging survey with the Dragonfly telescope of all luminous galaxies within a distance of 30 megaparsecs (Mpc) that are visible from New Mexico. Over the award period of 3 years, the investigators will obtain 40 hr deep images of a complete sample of 72 luminous nearby galaxies.Recent simulations suggest that the debris mostly lives at surface brightnesses of 29 to 31 mag per arcsec^2, fainter than the typical deep imaging limit of about 28 mag per arcsec^2. The investigators have constructed a telescope for the specific purpose of determining whether all galaxies have ultra low surface brightness tidal debris around them on scales of 30--100 kpc. The collected data will reach about 30 mag per arcsec^2 on 3 arcsec scales. The Dragonfly telescope is an array of telephoto lenses coupled with standard charge-coupled device (CCD) imagers. The latest generation of these lenses has nano-fabricated coatings that minimize scattered and reflected light. Together, these lenses constitute a perfectly baffled telescope with extremely fast, all-refractive optics and better scattered light control (by an order of magnitude) than existing reflecting telescopes.The investigating team will make the fully processed and calibrated images publicly available through a web interface. The project integrates education and research in the following ways: (1) The project is complementary to multi-year instrumentation efforts on large telescopes and is well-suited for graduate student training in astrophysical instrumentation. (2) The straightforward remote operation model lends itself well to classroom teaching and demonstrations. The telescope will be integrated into the undergraduate and graduate curriculum at Yale University and will also be used as a science demonstration tool for high school students.