The collapse and formation of galaxies. II - A control parameter for the Hubble sequence. III - The origin of the Hubble sequence

Abstract

view Abstract Citations (27) References (25) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS The Collapse and Formation of Galaxies. II. A Control Parameter for the Hubble Sequence Lake, George ; Carlberg, R. G. Abstract We use N-body models of the dissipational formation of galaxies to relate final morphologies to initial conditions. The simulations have four basic control parameters: the mass ratio of gas to dark matter, the initial angular momentum, the amount of dissipation, and the initial velocity dispersion of the dark matter. As expected, the morphology of the final stellar object is strongly correlated with its angular momentum, disks having high angular momentum and spheroids low angular momentum. However, the final angular momentum of the stars can be greatly diminished from its initial value due to the angular- momentum transfer. All of the control parameters have some influence on the evolution and final state, but the most significant control parameter for the morphology is the initial velocity dispersion of the dark matter. In a "warm" collapse, the gas settles into circular orbits creating a disk. In a "cold" collapse, angular-momentum transfer and a greater tendency for stars to form out of low-angular-momentum material leads to a dense, slowly rotating, elliptical object. The borderline between warm and cold collapse is a velocity dispersion at turnaround equal to ~20% of the final value. Publication: The Astronomical Journal Pub Date: November 1988 DOI: 10.1086/114908 Bibcode: 1988AJ.....96.1581L Keywords: Disk Galaxies; Galactic Evolution; Gravitational Collapse; Hubble Diagram; Many Body Problem; Angular Momentum; Dark Matter; Elliptical Galaxies; Luminosity; Red Shift; Star Distribution; Velocity Distribution; Astrophysics; GALAXIES: FORMATION full text sources ADS | Related Materials (2) Part 1: 1975IAUS...69..247L Part 3: 1988AJ.....96.1587L