大尺度結構與星系性質之間的關係：大尺度與小尺度環境對於星系的光學性質之研究

Abstract

我們進行了大尺度結構與星系的性質之間關係的調查研究，採用 了由SDSS DR8 Groups and Clusters of Galaxies Value-Added Catalogues，與MPA/JHU value-added galaxy catalog 兩者合併的data catalog。

在大尺度下星系並非是均勻的隨機分布在宇宙空間，而是分布在大 尺度結構，像是Filaments，Webs，Voids 之中。這種不同位置的變化，在對於每個星系的形成與演化的歷史，其所在的不同環境應該會對於 當地環境中的星系造成不同的影響。

由於已知星系的性質與其所在的環境是有相關性的，調查或研究星 系在各種不同大尺度環境與各種不同小尺度環境上的差異，並了解其 關係，能夠提供寶貴的資訊讓我們一定程度的了解星系的形成和演化 上的機制。例如環境密度以外的影響因素。

我們開發了一個定量的方法，用以客觀的描述星系周圍的宇宙大尺 度結構，進而定量地分析其星系性質與大尺度環境之間的關係。

我們的目標是要了解不同的大尺度環境與小尺度環境之中星系性質 的差異，與大尺度結構的形成與演化歷史之機制，經由調查研究星系 的性質，與其所處的大尺度環境或小尺度環境之間的關係性。

關鍵字：環境(Environment), 纖維狀結構(Filament), 星系(Galaxy), 大尺度結構(Large-Scale Structure), 史隆數位巡天(SDSS), 空洞(Void).

We are conducting the investigation of the relationship between large-scale structure and the kinematic& photometric properties of galaxies, using spectroscopic catalog from Sloan Digital Sky Survey Data Release 8 (SDSS dr8).

In large scale, galaxies are not distributed randomly, but lying inside the large-scale structure, such as, sheets, filaments, webs, and voids. This variation of the location should provide various environments for each galaxy to form and evolve. Since the properties of galaxies are known to correlated with their environments, investigations of the relationship between thegalaxies properties and the large-& small-scale environments should provide precious additional constraints for understanding the formation and evolution of galaxies, beyond well known environmental effect of smaller scale, such as the effect of local galaxy density.

We have developed quantitative methods to objectively characterize the large-scale structure of the universe surrounding galaxies, to quantitatively investigate the relation between the properties of galaxies and their large-scale environments.

Our methods characterized the large-scale environments by various measures such as ’Multi-Axis Density (MAD)’, ’Large-Scale-Filament Factor (LSFF)’, and ’Small-Scale-Filament Factor (SSFF)’.

Our goal is to understand the difference of galaxies in different environments by investigating the relation between the kinematic& photometric properties of galaxies and their large- & small-scale environments.

Key words: Environment, Filament, Galaxy, Large-Scale Structure, SDSS, Void