Jiangang Kang, Chang-Zhi Lu, Tong-Jie Zhang and Ming Zhu
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引用次数: 0
Abstract
This study presents results on detecting neutral atomic hydrogen (H i) 21 cm absorption in the spectrum of PKS PKS1413+13 at redshift z = 0.24670041. The observation was conducted by FAST, with a spectral resolution of 10 Hz, using 10 minutes of observing time. The global spectral profile is examined by modeling the absorption line using a single Gaussian function with a resolution of 10 kHz within a 2 MHz bandwidth. The goal is to determine the rate of the latest cosmic acceleration by directly measuring the redshift evolution of the H i 21 cm absorption line with Hubble flow toward a common background quasar over a decade or longer time span. This will serve as a detectable signal generated by the accelerated expansion of the Universe at redshift z < 1, referred to as redshift drift or the SL effect. The measured H i gas column density in this DLA system is approximately equivalent to the initial observation value, considering uncertainties of the spin temperature of a spiral host galaxy. The high signal-to-noise ratio of 57, obtained at a 10 kHz resolution, strongly supports the feasibility of using the H i 21 cm absorption line in DLA systems to accurately measure the redshift drift rate at a precision level of around 10−10 per decade.
本研究介绍了在红移 z = 0.24670041 的 PKS PKS1413+13 的光谱中探测到中性原子氢(H i)21 厘米吸收的结果。观测由 FAST 进行,光谱分辨率为 10 Hz,观测时间为 10 分钟。通过在 2 MHz 带宽内使用分辨率为 10 kHz 的单高斯函数对吸收线进行建模,对全局光谱剖面进行了研究。我们的目标是通过直接测量 H i 21 厘米吸收线的红移演变,确定最近宇宙加速的速率。这将作为红移 z < 1 时宇宙加速膨胀产生的可探测信号,即红移漂移或 SL 效应。考虑到螺旋宿主星系自旋温度的不确定性,在这个 DLA 系统中测得的 H i 气体柱密度大约相当于最初的观测值。在 10 kHz 分辨率下获得的 57 的高信噪比,有力地支持了在 DLA 系统中利用 H i 21 cm 吸收线精确测量红移漂移率的可行性,精确度约为每十年 10-10。
期刊介绍:
Research in Astronomy and Astrophysics (RAA) is an international journal publishing original research papers and reviews across all branches of astronomy and astrophysics, with a particular interest in the following topics:
-large-scale structure of universe formation and evolution of galaxies-
high-energy and cataclysmic processes in astrophysics-
formation and evolution of stars-
astrogeodynamics-
solar magnetic activity and heliogeospace environments-
dynamics of celestial bodies in the solar system and artificial bodies-
space observation and exploration-
new astronomical techniques and methods