期刊
ASTROPHYSICAL JOURNAL
卷 675, 期 2, 页码 1095-1105出版社
IOP PUBLISHING LTD
DOI: 10.1086/526412
关键词
dark matter; galaxies : clusters : general; galaxies : kinematics and dynamics; methods : numerical
We study galaxy mergers using a high-resolution cosmological hydro/N-body simulation with star formation and compare the measured merger timescales with theoretical predictions based on the Chandrasekhar formula. In contrast to Navarro et al., our numerical results indicate that the commonly used equation for the merger timescale given by Lacey and Cole systematically underestimates the merger timescales for minor mergers and overestimates those for major mergers. This behavior is partly explained by the poor performance of their expression for the Coulomb logarithm, ln (m(pri)/m(sat)). The two alternative forms ln (1 + m(pri)/m(sat)) and 1/2 ln [1 + (m(pri)/m(sat))(2)] for the Coulomb logarithm can account for the mass dependence of merger timescale successfully, but both of them underestimate the merger timescale by a factor 2. Since ln (1 + m(pri)/m(sat)) represents the mass dependence slightly better, we adopt this expression for the Coulomb logarithm. Furthermore, we find that the dependence of the merger timescale on the circularity parameter epsilon is much weaker than the widely adopted power law epsilon(0.78), whereas 0.94 epsilon(0.60) + 0.60 provides a good match to the data. Based on these findings, we present an accurate and convenient fitting formula for the merger timescale of galaxies in cold dark matter models.
作者
我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。
推荐
暂无数据