Collaborative Research: Advanced Digital Calibrators for 21cm Cosmology

现代宇宙学中最大的谜团之一是暗能量驱动的宇宙加速膨胀。星系巡天具有独特的能力来测量很久以前发生的宇宙膨胀，从而能够灵敏地测量暗能量的存在和特征。已经进行了使用光学望远镜对数十万个星系进行调查的实验，但这些调查仍然受到它们可以测量的星系数量的限制。无线电测量可以绕过这一限制，但需要精确了解进行测量的仪器。该提案将开发新的无线电信号技术和技术，以提高现有仪器进行这些实验的能力，从而更好地了解暗能量的性质。 该项目旨在扩大与学校教师的互动，以提高他们对射电天文学技术的了解，并将其传授给学校的学生。研究人员将设计、制作原型、表征和部署确定性数字校准信号，以改进21 cm宇宙学的校准。新的21厘米干涉仪需要精确的校准，特别是仪器光束，以消除明亮的前景和提取感兴趣的宇宙学信号。目前，为解决这一挑战而开发的非相干（仅功率）校准器限制了测量的动态范围，并且对仪器相位没有直接灵敏度。 这里提出的校准源解决了这些关键的差距，使全天空，高信噪比测量的复杂（真实的和虚构的）仪器光束。校准源将产生一个精确的信号，可以在无线电干涉仪相关器中进行相关，产生一个确定性的信号，可以用来测量光束的相位和幅度。 这个奖项反映了NSF的法定使命，并被认为是值得通过使用基金会的智力价值和更广泛的影响审查标准进行评估的支持。

One of the greatest mysteries in modern cosmology is the Dark Energy-driven accelerating expansion of the Universe. Galaxy surveys have a unique capability to measure the expansion of the Universe that occurred long ago, enabling a sensitive measurement of the presence and characteristics of Dark Energy. Experiments have been undertaken with surveys of hundreds of thousands of galaxies using optical telescopes, but those surveys are still limited by the number of galaxies they can measure. Radio surveys can get around this limitation but require precise understanding of the instrument making the measurement. This proposal will develop new radio signal technology and techniques to improve the capability of current instruments to do these experiments and thus enable a better understanding of the nature of Dark Energy. The project looks to expand interaction with school teachers to enhance their knowledge of radio astronomy techniques that can be relayed to students in schools.The investigators will design, prototype, characterize, and deploy deterministic digital calibration signals for the purpose of improved calibration for 21 cm cosmology. New 21 cm interferometers require precise calibration, particularly of the instrument beam, to remove bright foregrounds and extract the cosmological signal of interest. Currently, the incoherent (power only) calibrators developed to address this challenge limit the dynamic range of the measurement and also have no direct sensitivity to instrument phase. The calibration source proposed here addresses these critical gaps to make full-sky, high signal-to-noise measurements of the complex (real and imaginary) instrument beam. The calibration source will produce a precise signal that can be correlated in the radio interferometer correlator, yielding a deterministic signal that can be used to make measurements of the beam in both phase and amplitude. The project includes an expansion of existing programs with educators in learning digital signal processing techniques.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.