The dynamical survival of small-scale substructure in relaxed galaxy clusters

Abstract

view Abstract Citations (44) References (28) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS The Dynamical Survival of Small-Scale Substructure in Relaxed Galaxy Clusters Gonzalez-Casado, Guillermo ; Mamon, Gary A. ; Salvador-Sole, Eduard Abstract We consider the dynamical evolution of small-scale substructure in clusters within two extreme alternate scenarios for their possible origin: (1) the accretion of groups (or small clusters) on quasi-radial orbits and 2) the merger of clusters of similar masses, followed by the decoupling of their dense cores. Using simple analytical arguments and checking with numerical computations, we show that objects are destroyed by the tidal field of the global cluster potential if their mean density is small compared to the mean cluster density within the radius of closest approach of the group or detached core. Accreted groups and small clusters are thus tidally disrupted in one cluster crossing. Since the cores of clusters are much denser than groups, they are considerably more robust to tides, but the least massive are destroyed or severely stripped by tides, while the others are brought to the cluster center by dynamical friction (and subsequently merge) in less than one orbit. The longest lived substructures are detached cores, roughly 10 times less massive than the cluster, starting in near-circular orbits beyond 1 h^-1^ Mpc from the cluster center. Publication: The Astrophysical Journal Pub Date: October 1994 DOI: 10.1086/187548 arXiv: arXiv:astro-ph/9406066 Bibcode: 1994ApJ...433L..61G Keywords: Astronomical Models; Cosmology; Galactic Clusters; Galactic Evolution; Galactic Structure; Mathematical Models; Tides; Dynamical Systems; Equations Of Motion; Kinematics; Orbit Calculation; Orbital Mechanics; Astrophysics; GALAXIES: CLUSTERING; GALAXIES: KINEMATICS AND DYNAMICS; COSMOLOGY: THEORY; Astrophysics E-Print: accepted in ApJ Letters, 4 pages uuencoded compressed postscript (4 figures included), IAP preprint 465 full text sources arXiv | ADS |