== Fall 2021 LeCosPA Cosmology and Particle Astrophysics Seminars ==
Location : Room 7S1, LeCosPA center, NTU
if participants more than 20, we will change the lecture room from 7S1 to Room 7W3
Time : 11:00 am  12:00 am, Monday
Organizers : Naoki Watamura; TsungChe Liu
Date 
Name 
Title 
Affiliation 
File

Nov. 15

Prof. FengLi Lin

Weak Cosmic Censorship for Higher Derivative Gravity Theories

In this talk I will discuss how the weak cosmic censorship conjecture (WCCC) constrains the higher derivative gravity theories based on Wald's gedanken experiment by throwing the matter into the extremal or nearextremal black holes. We find that even though the WCCC still holds for the extremal black hole for the extremal black holes of quartic gravity theories, it can be violated for the nearextremal cases.


National Taiwan Normal University, Taiwan


Nov. 29, 10am

Prof. Geoff ChihFan Chen

H_0 measurement from timedelay cosmography.

The Hubble constant is one of the most important parameters in cosmology.
Its value directly sets the age, the size, and the critical density of the Universe.
Despite the success of the flat LCDM model, the derived Hubble constant from Planck data under the assumption of a flat LCDM model has 4.4sigma tension with the direct measurements.
If this tension is not due to the systematics, it may indicate the new physics beyond the standard cosmological model.
H_0 from timedelay lensing is a powerful independent tool for addressing the H_0 tension since it is independent of both Planck and the distance ladder.
One way to do this is to increase the number of highquality lens systems since this allows us to look for correlations and other effects due to systematics, and to do hierarchical approaches to assess known systematic effects.
Keck AO data is not only the key component to increase the precision of H0 measurement but also provides systematic checks with the H_0 results based on HST imaging.
In this talk, I will present the current H_0 measurement, the systematic checks, and the future prospective of H0LiCOW/TDCOSMO collaboration.


University of California, Los Angeles , United States


Dec. 6

Prof. Yen Chin Ong


Yangzhou University, China


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