Color gradients of the galaxies at 0.5

Color gradients of the galaxies at 0.5 < z < 1 Ⅰ. Dependence on galaxy global properties

作　　者：Zhi-Xiong Liang Cheng Li 

机构地区：[1]Shanghai Astronomical Observatory,Chinese Academy of Sciences,Shanghai 200030,China [2]University of Chinese Academy of Sciences,Beijing 100049,China [3]Tsinghua Center for Astrophysics and Physics Department,Tsinghua University,Beijing 100084,China

出　　处：《Research in Astronomy and Astrophysics》2018年第11期133-144,共12页天文和天体物理学研究（英文版）

基　　金：supported by the National Key Basic Research Program of China(No.2015CB857004);the National Natural Science Foundation of China(Grant Nos.11173045,11233005,11325314 and 11320101002)

摘　　要：We investigate the color gradients of galaxies at 0.5 < z < 1.0, using a sample of ~35 000 galaxies with both spectroscopy from the final data release of the VIMOS Public Extragalactic Redshift Survey(VIPERS), and photometry in ultraviolet/optical/near-infrared bands from the VIPERS-MultiLambda Survey(VIPERS-MLS) and the Canada-France-Hawaii Telescope Legacy Survey(CFHTLS).We estimate rest-frame colors, stellar mass, star formation rate from fitting the Spectral Energy Distribution(SED) for each galaxy, as well as a two-zone color ?(u-r), defined as the difference in rest-frame(u-r) color between the outer and inner region of the galaxy. We find that the two-zone color shows weak or no correlations with all galaxy properties considered except stellar mass. On average, ?(u-r) decreases with increasing stellar mass, indicating relatively red colors in galactic centers of more massive galaxies. We then compare the properties of "red-cored" and "blue-cored" galaxies,defined to have either a negative or a positive ?(u-r) respectively. Although the two types of galaxies show similar distributions in most properties, we find massive red-cored galaxies with M*> 1010.5M⊙to have larger sizes at given stellar mass(thus lower surface mass densities), and less massive red-cored galaxies with M*< 1010.5M⊙to have lower central galaxy fraction. These findings can be understood if one assumes that the star formation process happens from inside out, in the same way as recently emphasized in studies of low-z galaxies. The similarity between the galaxies at intermediate redshifts and those at low redshifts supports the idea that galaxy evolution since z~1 has been mainly driven by secular processes internal to galaxies rather than galaxy mergers or external environment.We investigate the color gradients of galaxies at 0.5 < z < 1.0, using a sample of ~35 000 galaxies with both spectroscopy from the final data release of the VIMOS Public Extragalactic Redshift Survey(VIPERS), and photometry in ultraviolet/optical/near-infrared bands from the VIPERS-MultiLambda Survey(VIPERS-MLS) and the Canada-France-Hawaii Telescope Legacy Survey(CFHTLS).We estimate rest-frame colors, stellar mass, star formation rate from fitting the Spectral Energy Distribution(SED) for each galaxy, as well as a two-zone color ?(u-r), defined as the difference in rest-frame(u-r) color between the outer and inner region of the galaxy. We find that the two-zone color shows weak or no correlations with all galaxy properties considered except stellar mass. On average, ?(u-r) decreases with increasing stellar mass, indicating relatively red colors in galactic centers of more massive galaxies. We then compare the properties of "red-cored" and "blue-cored" galaxies,defined to have either a negative or a positive ?(u-r) respectively. Although the two types of galaxies show similar distributions in most properties, we find massive red-cored galaxies with M_*> 10^(10.5) M_⊙to have larger sizes at given stellar mass(thus lower surface mass densities), and less massive red-cored galaxies with M_*< 10^(10.5) M_⊙to have lower central galaxy fraction. These findings can be understood if one assumes that the star formation process happens from inside out, in the same way as recently emphasized in studies of low-z galaxies. The similarity between the galaxies at intermediate redshifts and those at low redshifts supports the idea that galaxy evolution since z^1 has been mainly driven by secular processes internal to galaxies rather than galaxy mergers or external environment.

关 键 词：galaxies: photometry galaxies: statistics galaxies: evolution 

分 类 号：P[天文地球]