Mechanisms for biased galaxy formation
Abstract
A 'flat' universe with Omega = 1, attractive on theoretical grounds, can only be reconciled with virial-type analyses if galaxies are more 'clumped' than the overall mass distribution even on scales up to 10-20 Mpc. Formation of conspicuous galaxies must be favored in high-density regions, and inhibited in voids. Mechanisms are discussed for bringing this about, particularly in the context of the 'cold dark matter' cosmogony. There are two forms in which energy from early galaxies could provide a pressure that prevents condensation of further galaxies more than about 20 Mpc away: (1) fast particles, or (2) UV radiation pressure, coupled to the intergalactic gas via Lyman-alpha scattering. Other processes for 'biasing' bright galaxies towards high-density regions are outlined. If the universe has Omega = 1, with baryons contributing Omega(b) = 0.1, then up to 90 percent of these baryons could remain uncondensed in intergalactic space or be in systems with M/L more than 100 solar units.
- Publication:
-
Monthly Notices of the Royal Astronomical Society
- Pub Date:
- April 1985
- DOI:
- 10.1093/mnras/213.1.75P
- Bibcode:
- 1985MNRAS.213P..75R
- Keywords:
-
- Baryons;
- Cosmology;
- Galactic Evolution;
- Universe;
- Brightness;
- Dark Matter;
- Galactic Clusters;
- Intergalactic Media;
- Mass Distribution;
- Ultraviolet Radiation;
- Astrophysics