Speaker: Yihan Wu

Institute: Xiamen University

Host: Min Du

Time: 14:30-16:30, Thursday, May, 12

Location: Physics Building 552 (online)

Abstract:

‘A long time ago in a galaxy far, far away ………’

This is an opening words appeared in the movie ‘Star War’. However, for this speech, it should be

‘A long history in our Universe far, far away………’

In astronomy, the distance measurement of the celestial object has been a challengeable but appealing task. It is relevant to our understanding of the spatial scale in the Universe and even of the cosmic expansion. The parallax,  Cepheid Variables, Type-Ia supernovae, and Tully-Fisher relation are the tools that have been utilized for the distance measurement in the local Universe. Furthermore, thanks to the recent-year high-tech telescopes, we astronomers are able to observe the galaxies located beyond the redshift of 1 (z > 1). By detecting the atomic/molecular (CO, SO, C, and so on) lines emitted from these high-redshift (z > 1) galaxies, we are also allowed to understand more about the environments in the early-time Universe. Here in this speech, we will talk about how we measure the cosmic distances of the galaxies in z > 1 through their characteristics measured in the atomic/molecular lines.

Bio:

Yi-Han Wu received his Ph. D. degree at Tsing-Hua University in Taiwan (NTHU), in 2019. After his Ph. D., he went to Stanford University as a postdoc researcher from 2019 to 2020. Now, he is joining his postdoc program at XMU as a postdoc researcher. His research topic focuses on how to use the characteristics (such as luminosity, linewidth, gass mass) of galaxies to perform the distance measurement without any model assumption, which will be helpful to expand our horizon in the Universe.

Reference :

[1] : https://academic.oup.com/mnras/article/483/4/5281/5284985?searchresult=1

[2] : https://ui.adsabs.harvard.edu/abs/2019MNRAS.483.5281W/abstract