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| Main Authors: | , , , |
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| Format: | Preprint |
| Published: |
2023
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| Subjects: | |
| Online Access: | https://arxiv.org/abs/2308.08851 |
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| _version_ | 1866909567638568960 |
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| author | Kang, Jiangang Lu, Chang-Zhi Zhang, TongJie Zhu, Ming |
| author_facet | Kang, Jiangang Lu, Chang-Zhi Zhang, TongJie Zhu, Ming |
| contents | This study presents results on detecting neutral atomic hydrogen (HI) 21cm absorption in the spectrum of PKS1413+135 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 redshift evolution of H I 21 cm absorption line with Hubble flow towards a same 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 $\dot{z}$ or the SL effect. The measured HI 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. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2308_08851 |
| institution | arXiv |
| publishDate | 2023 |
| record_format | arxiv |
| spellingShingle | Toward a direct measurement of the cosmic acceleration: The pilot observation of H I 21cm absorption line at FAST Kang, Jiangang Lu, Chang-Zhi Zhang, TongJie Zhu, Ming Cosmology and Nongalactic Astrophysics This study presents results on detecting neutral atomic hydrogen (HI) 21cm absorption in the spectrum of PKS1413+135 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 redshift evolution of H I 21 cm absorption line with Hubble flow towards a same 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 $\dot{z}$ or the SL effect. The measured HI 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. |
| title | Toward a direct measurement of the cosmic acceleration: The pilot observation of H I 21cm absorption line at FAST |
| topic | Cosmology and Nongalactic Astrophysics |
| url | https://arxiv.org/abs/2308.08851 |