On the track to measure the apparent cosmic acceleration: observation test and forecast on FAST. (arXiv:1905.01184v1 [astro-ph.CO])

On the track to measure the apparent cosmic acceleration: observation test and forecast on FAST. (arXiv:1905.01184v1 [astro-ph.CO])
<a href="http://arxiv.org/find/astro-ph/1/au:+Jiao_K/0/1/0/all/0/1">Kang Jiao</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Zhang_J/0/1/0/all/0/1">Jian-Chen Zhang</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Zhang_T/0/1/0/all/0/1">Tong-Jie Zhang</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Yu_H/0/1/0/all/0/1">Hao-Ran Yu</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Zhu_M/0/1/0/all/0/1">Ming Zhu</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Li_D/0/1/0/all/0/1">Di Li</a>

The cosmic redshift drift is a powerful direct probe in investigating the
dynamics of the universe. The Parkes telescope and upcoming commensal survey
CRAFTS using FAST telescope have the potential to monitor thousands of HI
absorption systems. It offers us a promising prospect for directly measuring
the apparent cosmic acceleration by gauging its spectral line drift
statistically. Aiming to actualize this via the future sky survey with FAST, we
execute an observation test using the Parkes telescope to explore the technical
requirements and feasibility of such observation. We propose a combined
observational mode to perform the redshift drift measurement. Based on
statistical estimation, we predict that about 800 HI absorption systems will be
discovered for 1 year CRAFTS survey. For 10 years of consecutive targeted
spectroscopic observation with the level of $0.1 rm Hz$ resolution, we could
detect the first order derivative of the cosmological redshift.

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