科研之友
微信
新浪微博
Facebook
分享链接
摘要
The accreted component of stellar haloes is composed of the contributions of several satellites, falling on to their host with their different masses, at different times, on different orbits. This work uses a suite of idealized, collisionless N-body simulations of minor mergers and a particle-tagging technique to understand how these different ingredients shape each contribution to the accreted halo, in both density and kinematics. I find that more massive satellites deposit their stars deeper into the gravitational potential of the host, with a clear segregation enforced by dynamical friction. Earlier accretion events contribute more to the inner regions of the halo; more concentrated subhaloes sink deeper through increased dynamical friction. The orbital circularity of the progenitor at infall is only important for low-mass satellites: dynamical friction efficiently radializes the most massive minor mergers erasing the imprint of the infall orbit for satellite-to-host virial mass ratios greater than or similar to 1/20. The kinematics of the stars contributed by each satellite is also ordered with satellite mass: low-mass satellites contribute fast-moving populations, in both ordered rotation and radial velocity dispersion. In turn, contributions by massive satellites have lower velocity dispersion and lose their angular momentum to dynamical friction, resulting in a strong radial anisotropy.
- 出版日期2017-1
