Astronomy and Astrophysics – Astrophysics
Scientific paper
Jan 2008
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2008aipc..966...69j&link_type=abstract
RELATIVISTIC ASTROPHYSICS: 4th Italian-Sino Workshop. AIP Conference Proceedings, Volume 966, pp. 69-70 (2008).
Astronomy and Astrophysics
Astrophysics
Galaxy Mergers, Collisions, And Tidal Interactions, Star Formation, Dark Matter, Time Series Analysis, Time Variability, Galaxy Clusters
Scientific paper
In this talk, we present our recent study of galaxy mergers in 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(mpri/msat). The two alternative forms ln(1+mpri/msat) and 1/2 ln[1+(mpri/msat)2] for the Coulomb logarithm can account for the mass dependence of merger timescale successfully, but both of them underestimate the merger time scale by a factor 2. Since ln(1+mpri/msat) 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 ɛ is much weaker than the widely adopted power-law ɛ0.78, whereas 0.94*ɛ0.60+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.
Faltenbacher Aandreas
Jiang C. Y.
Jing Yi-Peng
Li Cheng
Lin Wei-Peng
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