The tidal stripping of satellites
نویسندگان
چکیده
We present an improved analytic calculation for the tidal radius of satellites and test our results against N-body simulations. The tidal radius in general depends upon four factors: the potential of the host galaxy, the potential of the satellite, the orbit of the satellite and, which is new to this paper, the orbit of the star within the satellite. We demonstrate that this last point is critical and suggest using three tidal radii to cover the range of orbits of stars within the satellite. In this way we show explicitly that prograde star orbits will be more easily stripped than radial orbits; while radial orbits are more easily stripped than retrograde ones. This result has previously been established by several authors numerically, but can now be understood analytically. Over short times ( < ∼ 1− 2 Gyrs ∼ 1 satellite orbit), we find excellent agreement between our analytic and numerical models. Over longer times, star orbits within the satellite are transformed by the tidal field of the host galaxy. In a Hubble time, this causes a convergence of the three limiting tidal radii towards the prograde stripping radius. We predict that, beyond the prograde stripping radius, the velocity dispersion is tangentially anisotropic.
منابع مشابه
Baryons Matter: Why Luminous Satellite Galaxies Have Reduced Central Masses
Using high-resolution cosmological hydrodynamical simulations of Milky Way-massed disk galaxies, we demonstrate that supernovae feedback and tidal stripping lower the central masses of bright (−15 < MV < −8) satellite galaxies. These simulations resolve high-density regions, comparable to giant molecular clouds, where stars form. This resolution allows us to adopt a prescription for H2 formatio...
متن کاملCollisional versus Collisionless Dark Matter.
We compare the structure and substructure of dark matter halos in model universes dominated by collisional, strongly self-interacting dark matter (SIDM) and collisionless, weakly interacting dark matter (CDM). While SIDM virialized halos are more nearly spherical than CDM halos, they can be rotationally flattened by as much as 20% in their inner regions. Substructure halos suffer ram-pressure t...
متن کاملDisruption of satellites in cosmological haloes
We investigate how the survival of dark matter satellites inside virialized halos depends on tidal stripping and dynamical friction. We use an analytic approach and then compare the results with N-Body simulations. Both the satellites and the primary halos are similar to cosmological haloes and have NFW density profiles. Satellites can either merge with the primary halo or continue to move on b...
متن کاملMechanisms of baryon loss for dark satellites in cosmological smoothed particle hydrodynamics simulations
We present a study of satellites in orbit around a high-resolution, smoothed particle hydrodynamics (SPH) galaxy simulated in a cosmological context. The simulated galaxy is approximately of the same mass as the Milky Way. The cumulative number of luminous satellites at z= 0 is similar to the observed system of satellites orbiting the Milky Way although an analysis of the satellite mass functio...
متن کاملDwarf spheroidals with tidal tails and structure formation
Recent N-Body simulations have shown that dIrrs evolve into dSphs owing to the strong tidal perturbation of the Milky Way. Satellites whose dark matter halos have a core or an NFW profile with a concentration c < 5 undergo severe stripping even on low eccentricity orbits and their remnants have projected stellar profiles that become flat at large radii as observed in some of the dSphs. Satellit...
متن کامل