星系合併在大質量星系生命中扮演的角色


Seminar - The Role of Galaxy Merging in the Life of Massive Galaxies

In the local Universe, the most massive galaxies of above 1x10^11 solar masses are typically situated at the centres of galaxy clusters or groups, and have elliptical light profiles. They have uniformly old stellar populations, containing mostly stars formed when the Universe was only 2-3 Gyrs old. Merging has been proposed as an important driver for their evolution, possibly responsible for morphological transformations, size growth, ignition of active galactic nuclei as well as both triggering and quenching of star formation. Accurate measurements of the merging history of massive galaxies is thus instrumental to understand their evolution. While several measurements of the merging fraction of massive galaxies up to z~3 exist to date, they lead to discrepant conclusions of whether the fraction is increasing or diminishing.

My recent work resolves this discrepancy through the accurate measurement of the galaxy merger fraction up to z=3 in the COSMOS field. Based on the largest photometrically identified sample of mergers at z>1, the discrepancy across previous studies is found to be due to a selection effect. I will discuss the implications of our results in the context of massive galaxy evolution, namely stellar mass accretion history, number density evolution and size growth.

時間:2015.12.17(四) 11:00
地點:香港大學 莊月明物理樓 522室
講者:Dr. Allison Man (European Southern Observatory)
語言:英語

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【訊息由張詠倫提供】

此活動由香港大學物理學系主辦。

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