Investigating Dark Matter Distribution in Early-Type Galaxies

• Main Authors: Cheng, Ting Yun, 鄭婷筠
• Other Authors: Jiang, Ing Guey
• Format: Others
• Language: en_US
• Published: 2016
• Online Access: http://ndltd.ncl.edu.tw/handle/24264128135080450339

碩士 === 國立清華大學 === 天文研究所 === 104 === Through Jeans equation and functional total Mass-to-Light ratio (M/L), we study the mass distribution in Early-Type Galaxies (ETGs). Fourteen galaxies from Hubble Legacy Archive (HLA) in F555W wavelength have been studied. We introduce a new probable form for M/L, i.e., power-law M/L and considered three kinds of anisotropic condition (Isotropic, Generally constant, Osipkov-Merritt model). Being different from literature (Napolitano et al. 2005; Alabi et al. 2016), we set logarithmic gradient of M/L as a free parameter. There are eleven galaxies have a best fit with power-law M/L in our work. Additionally, there is a new result from literature that 8 galaxies have negative value in the logarithmic gradient of M/L. The negative value in logarithmic gradient shows a non-significant dark halos in ETGs and further indicates the gathering of dark matter at small radii. Besides that, logarithmic gradient correlates with stellar mass, dark matter mass, and Supermassive black hole (SMBH) mass, etc. Dark matter content also shows the linear correlation with stellar mass, luminosity and Supermassive black hole (SMBH) mass. Additionally, we have the conclusion that brighter galaxies have larger value of logarithmic gradient, more dark matter mass, and more massive SMBH. On the contrary, fainter galaxies have smaller value of logarithmic gradient, less dark matter mass, less massive SMBH, and they show a relatively weak dark halo as well.