An Overview of CHIME, the Canadian Hydrogen Intensity Mapping Experiment
An Overview of CHIME, the Canadian Hydrogen Intensity Mapping Experiment
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DOI：
10.3847/1538-4365/ac6fd9
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发表时间：
2022-01
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通讯作者：
M. Amiri;K. Bandura;Ana Boskovic;Tianyue Chen;J. Cliche;M. Deng;N. Denman;M. Dobbs;M. Fandino;S. Foreman;M. Halpern;D. Hanna;A. Hill;G. Hinshaw;C. Höfer;Joseph W. Kania;P. Klages;T. Landecker;Joshua MacEachern;K. Masui;J. Mena-Parra;N. Milutinovic;A. Mirhosseini;L. Newburgh;Rick Nitsche;A. Ordog;U. Pen;T. Pinsonneault-Marotte;Ava Polzin;A. Reda;A. Renard;J. Shaw;S. Siegel;Saurabh Singh;R. Smegal;I. Tretyakov;Kwinten Van Gassen;K. Vanderlinde;Haochen Wang;D. Wiebe;James S. Willis;D. Wulf
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作者：
M. Amiri;K. Bandura;Ana Boskovic;Tianyue Chen;J. Cliche;M. Deng;N. Denman;M. Dobbs;M. Fandino;S. Foreman;M. Halpern;D. Hanna;A. Hill;G. Hinshaw;C. Höfer;Joseph W. Kania;P. Klages;T. Landecker;Joshua MacEachern;K. Masui;J. Mena-Parra;N. Milutinovic;A. Mirhosseini;L. Newburgh;Rick Nitsche;A. Ordog;U. Pen;T. Pinsonneault-Marotte;Ava Polzin;A. Reda;A. Renard;J. Shaw;S. Siegel;Saurabh Singh;R. Smegal;I. Tretyakov;Kwinten Van Gassen;K. Vanderlinde;Haochen Wang;D. Wiebe;James S. Willis;D. Wulf
加拿大氢强度测绘实验（英语：Canadian Hydrogen Intensity Mapping Experiment，CHIME）是一个在400-800 MHz频段运行的漂移扫描射电望远镜。CHIME位于加拿大不列颠哥伦比亚省彭蒂克顿附近的自治领射电天体物理观测站。该仪器被设计用于绘制红移范围为0.8-2.5的中性氢，以限制宇宙的膨胀历史。这一目标推动了仪器的设计特征。CHIME由四个平行的圆柱形反射器组成，南北方向，每个100 m × 20 m，并配备了256个单元的双极化线性馈电阵列。CHIME观测到在任何特定时刻覆盖整个子午线的两度宽的条纹，由于地球的自转，每天观测四分之三的天空。FX相关器利用现场可编程门阵列和图形处理单元对信号进行数字化和相关，并为宇宙学、快速射电暴、脉冲星、甚长基线干涉测量和21 cm吸收器后端生成不同的相关产品。对于宇宙学后端，Nfeed 2相关矩阵形成为1024频率通道在整个频带每31毫秒。一个数据接收器系统应用校准和标记，并为我们的主要宇宙学数据产品，堆栈冗余基线和集成为10秒。我们提出了一个概述的仪器，其性能指标的基础上的第一个3年的科学数据，我们描述了目前的进展，在表征CHIME的主光束响应。我们还提出了来自CHIME数据的天空地图，我们正在使用这些地图的版本进行宇宙学叠加分析，以及银河系前景的调查。
The Canadian Hydrogen Intensity Mapping Experiment (CHIME) is a drift scan radio telescope operating across the 400–800 MHz band. CHIME is located at the Dominion Radio Astrophysical Observatory near Penticton, BC, Canada. The instrument is designed to map neutral hydrogen over the redshift range 0.8–2.5 to constrain the expansion history of the universe. This goal drives the design features of the instrument. CHIME consists of four parallel cylindrical reflectors, oriented north–south, each 100 m × 20 m and outfitted with a 256-element dual-polarization linear feed array. CHIME observes a two-degree-wide stripe covering the entire meridian at any given moment, observing three-quarters of the sky every day owing to Earth’s rotation. An FX correlator utilizes field-programmable gate arrays and graphics processing units to digitize and correlate the signals, with different correlation products generated for cosmological, fast radio burst, pulsar, very long baseline interferometry, and 21 cm absorber back ends. For the cosmology back end, the Nfeed2 correlation matrix is formed for 1024 frequency channels across the band every 31 ms. A data receiver system applies calibration and flagging and, for our primary cosmological data product, stacks redundant baselines and integrates for 10 s. We present an overview of the instrument, its performance metrics based on the first 3 yr of science data, and we describe the current progress in characterizing CHIME’s primary beam response. We also present maps of the sky derived from CHIME data; we are using versions of these maps for a cosmological stacking analysis, as well as for investigation of Galactic foregrounds.