Radial distributions of surface mass density and mass-to-luminosity ratio in spiral galaxies

PASJ: Publications of the Astronomical Society of Japan

Sofue, Yoshiaki¹ 

[1] Institute of Astronomy, The University of Tokyo, 2-21-1 Osawa, Mitaka, Tokyo 181-0015, Japan

关键词: galaxies: kinematics and dynamics;    galaxies: spiral;    galaxies: structure;   

DOI  :  10.1093/pasj/psy014

学科分类：天文学(综合)

来源: Oxford University Press

【 摘 要 】

We present radial profiles of the surface mass density (SMD) in spiral galaxies directly calculated using rotation curves of two approximations of flat-disk (SMD-F) and spherical mass distribution (SMD-S). The SMDs are combined with surface brightness using photometric data to derive radial variations of the mass-to-luminosity ratio (ML). It is found that the ML generally has a central peak or a plateau, and decreases to a local minimum at R ∼ 0.1–0.2 h, where R is the radius and h is the scale radius of optical disk. The ML, then, increases rapidly until ∼0.5 h, and is followed by gradual rise till ∼2 h, remaining at around ∼2 [|$M_{\odot}\,L^{-1}_{\odot}$|] in the w1 band (infrared λ3.4 μm) and |$\sim 10\ [M_\odot L_\odot ^{-1}]$| in the r band (λ6200–7500 Å). Beyond this radius, the ML increases steeply with approaching the observed edges at R ∼ 5 h, attaining to as high values as ∼20 in w1 and |$\sim 10^2\ [M_\odot L_\odot ^{-1}]$| in the r band, which are indicative of dominant dark matter. The general properties of the ML distributions will be useful for constraining cosmological formation models of spiral galaxies.

【 授权许可】

CC BY