本帖最後由 iheby 於 2017-3-23 23:45 編輯
重力透鏡延時宇宙學 ＠香港大學物理系
SEMINAR:- Cosmology from Gravitational Lens Time Delays
Strong gravitational lens systems with time delays between the multiple images are a powerful probe of cosmology and astrophysics. In particular, the time-delay distance from such a system is primarily sensitive to the Hubble constant (H0) that is key to probing dark energy, neutrino physics, and the spatial curvature of the Universe, as well as discovering new physics. The H0 Lenses In COSMOGRAIL’s Wellspring (H0LiCOW) project aims to measure H0 to <3.5% precision from five lensed quasars using deep Hubble Space Telescope imaging, precise time delay measurements from the COSMOGRAIL monitoring project, a measurement of the velocity dispersion of the lens galaxies, and a characterization of the mass distribution along the line of sight. The most recent H0LiCOW analysis of the system HE 0435-1223 is able to constrain the time-delay distance to a precision of ~8%. In combination with the previous two H0LiCOW lenses, we constrain H0 to ~3.8% precision for a flat Lambda CDM cosmology. These results are consistent with independent determinations of H0 using the distance ladder method and are in moderate tension with the latest Planck results for a similar cosmology, hinting at possible new physics beyond the standard LCDM model and highlighting the importance of this independent probe.
時間：2017.03.30(四) 14:30
地點：香港大學 莊月明物理樓105室
講者：黃活生 博士 Dr. Kenneth WONG (East Asia Core Observatories Association)
語言：英語
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強調現有星團成員與行星狀星雲在我們的銀河 @香港大學物理系
SEMINAR of RPg Student:- Planetary Nebulae in our Galaxy with Emphasis on those that Present Cluster Membership
The study of Planetary Nebulae (PNe) provides us vital clues for the science behind the formation and evolution of entire galaxies. Despite the fact that recent surveys (e.g. Parker et al. 2005) have doubled their detections, there are various issues upon these spectacular objects that remain unresolved.
To date, no extensive search for cluster PNe has ever been held in spite of their crucial role (Parker et al. 2011). The aim of the proposed project is the detection of new Planetary Nebulae in our Galaxy and especially in clusters, the verification of their cluster membership and the study of their properties with the aid of new observational techniques and modeling methods (see Parker et al. 2012a).
This study will provide us important information for both the formation and evolution of Planetary Nebulae and apparently for the ecology of our own Galaxy.
時間：2017.03.31(五) 14:00
地點：香港大學 莊月明物理樓518室
講者：Vasilik FRAGKOU (香港大學)
語言：英語
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