David R. DeBoer, Aaron R. Parsons, James E. Aguirre, Paul Alexander, Zaki S. Ali, Adam P. Beardsley, Gianni Bernardi, Judd D. Bowman, Richard F. Bradley, Chris … 展开作者
David R. DeBoer, Aaron R. Parsons, James E. Aguirre, Paul Alexander, Zaki S. Ali, Adam P. Beardsley, Gianni Bernardi, Judd D. Bowman, Richard F. Bradley, Chris L. Carilli, Carina Cheng, Eloy de Lera Acedo, Joshua S. Dillon, Aaron Ewall-Wice, Gcobisa Fadana, Nicolas Fagnoni, Randall Fritz, Steve R. Furlanetto, Brian Glendenning, Bradley Greig, Jasper Grobbelaar, Bryna J. Hazelton, Jacqueline N. Hewitt, Jack Hickish, Daniel C. Jacobs, Austin Julius, MacCalvin Kariseb, Saul A. Kohn, Telalo Lekalake, Adrian Liu, Anita Loots, David MacMahon, Lourence Malan, Cresshim Malgas, Matthys Maree, Nathan Mathison, Eunice Matsetela, Andrei Mesinger, Miguel F. Morales, Abraham R. Neben, Nipanjana Patra, Samantha Pieterse, Jonathan C. Pober, Nima Razavi-Ghods, Jon Ringuette, James Robnett, Kathryn Rosie, Raddwine Sell, Craig Smith, Angelo Syce, Max Tegmark, Nithyanandan Thyagarajan, Peter K. G. Williams, Haoxuan Zheng
The Hydrogen Epoch of Reionization Array (HERA) is a staged experiment to measure 21 cm emission from the primordial intergalactic medium (IGM) throughout cosmic reionization ($z=6-12$), and to explore earlier epochs of our Cosmic Dawn ($z\sim30$). During these epochs, early stars and black holes heated and ionized the IGM, introducing fluctuations in 21 cm emission. HERA is designed to characterize the evolution of the 21 cm power spectrum to constrain the timing and morphology of reionization, the properties of the first galaxies, the evolution of large-scale structure, and the early sources of heating. The full HERA instrument will be a 350-element interferometer in South Africa consisting of 14-m parabolic dishes observing from 50 to 250 MHz. Currently, 19 dishes have been deployed on site and the next 18 are under construction. HERA has been designated as an SKA Precursor instrument.
In this paper, we summarize HERA's scientific context and provide forecasts for its key science results. After reviewing the current state of the art in foreground mitigation, we use the delay-spectrum technique to motivate high-level performance requirements for the HERA instrument. Next, we present the HERA instrument design, along with the subsystem specifications that ensure that HERA meets its performance requirements. Finally, we summarize the schedule and status of the project. We conclude by suggesting that, given the realities of foreground contamination, current-generation 21 cm instruments are approaching their sensitivity limits. HERA is designed to bring both the sensitivity and the precision to deliver its primary science on the basis of proven foreground filtering techniques, while developing new subtraction techniques to unlock new capabilities. The result will be a major step toward realizing the widely recognized scientific potential of 21 cm cosmology.
New Limits on Polarized Power Spectra at 126 and 164 MHz: Relevance to Epoch of Reionization Measurements
偏振前景发射是测量高红移21 cm HI再电离期涨落功率谱的一个潜在的污染源。使用Donald C。Backer精密阵列探测再电离时期（PAPER），我们提出了在两个频段，以126 MHz为中心的所有四个斯托克斯参数的观测功率谱的限制（$z=10.3$）和164 MHz（$z=7.66$）进行为期三个月的观测活动，部署32个天线，在$z=7.7$（Parsons et al 2014）和$7.5 < z < 10.5$（Jacobs et al 2014）中报告了非偏振功率谱结果。本文中的功率谱的处理方式与那些作品中的相同，并且没有显示出偏振功率的确定性检测。这种未检测到的现象似乎主要是由于电离层旋转测量波动对极化功率的抑制，这强烈影响了斯托克斯Q和U。我们能够证明，在Parsons等人2014年和Jacobs等人2014年报告的限值水平下，极化泄漏的净效应可以忽略不计。
