Reionization and the Abundance of Galactic Satellites
Top Cited Papers
- 20 August 2000
- journal article
- research article
- Published by American Astronomical Society in The Astrophysical Journal
- Vol. 539 (2), 517-521
- https://doi.org/10.1086/309279
Abstract
One of the main challenges facing standard hierarchical structure formation models is that the predicted abundance of Galactic subhalos with circular velocities vc ~ 10-30 km s-1 is an order of magnitude higher than the number of satellites actually observed within the Local Group. Using a simple model for the formation and evolution of dark halos, based on the extended Press-Schechter formalism and tested against N-body results, we show that the theoretical predictions can be reconciled with observations if gas accretion in low-mass halos is suppressed after the epoch of reionization. In this picture, the observed dwarf satellites correspond to the small fraction of halos that accreted substantial amounts of gas before reionization. The photoionization mechanism naturally explains why the discrepancy between predicted halos and observed satellites sets in at vc ~ 30 km s-1, and for reasonable choices of the reionization redshift (zre ~ 5-12) the model can reproduce both the amplitude and shape of the observed velocity function of galactic satellites. If this explanation is correct, then typical bright galaxy halos contain many low-mass dark matter subhalos. These might be detectable through their gravitational lensing effects, through their influence on stellar disks, or as dwarf satellites with very high mass-to-light ratios. This model also predicts a diffuse stellar component produced by large numbers of tidally disrupted dwarfs, perhaps sufficient to account for most of the Milky Way's stellar halo.Keywords
This publication has 40 references indexed in Scilit:
- The Dearth of Halo Dwarf Galaxies: Is There Power on Short Scales?Physical Review Letters, 2000
- The Photoevaporation of Dwarf Galaxies during ReionizationThe Astrophysical Journal, 1999
- Discovery of a Nearby Low Surface Brightness Spiral GalaxyThe Astronomical Journal, 1999
- Dark matter haloes within clustersMonthly Notices of the Royal Astronomical Society, 1998
- The Cores of Dark Matter–Dominated Galaxies: Theory versus ObservationsThe Astrophysical Journal, 1998
- Evidence for substructure in lens galaxies?Monthly Notices of the Royal Astronomical Society, 1998
- The Delayed Formation of Dwarf GalaxiesThe Astrophysical Journal, 1997
- RR Lyrae Variable Star Distribution in the Galactic HaloThe Astronomical Journal, 1996
- Reionization in a cold dark matter universe: The feedback of galaxy formation on the intergalactic mediumThe Astrophysical Journal, 1994
- Galactic disks, infall, and the global value of OmegaThe Astrophysical Journal, 1992