Evidence against Baryonic Dark Matter in Elliptical Galaxies
Abstract
The presence of a dark halo, ~ 20 times more massive than the X-ray emitting gas, is necessary to explain the observations of X-ray halos surrounding some elliptical galaxies. We consider the possibility that the dark matter is baryonic, and, with the exception of massive black holes, we find that baryons are unlikely to be the dominant form of dark matter in elliptical galaxies. In particular, we use optical observations of M87 to determine a 2 σ lower limit on the mass-to-light (M/L) ratio of the galaxy and find M/L > 565 at r ~ 200 kpc. We use this limit to place a lower bound on the slope, 1 + x, of the low-mass portion of the initial mass function and find x >~ 2. This is significantly larger than observationally determined values of the slope. We also argue against the presence of other forms of baryonic dark matter.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- November 1989
- DOI:
- 10.1086/168047
- Bibcode:
- 1989ApJ...346..648H
- Keywords:
-
- Baryons;
- Computational Astrophysics;
- Dark Matter;
- Elliptical Galaxies;
- Black Holes (Astronomy);
- Galactic Structure;
- Gravitational Collapse;
- Mass To Light Ratios;
- Nuclear Fusion;
- Astrophysics;
- DARK MATTER;
- GALAXIES: INTERSTELLAR MATTER;
- GALAXIES: STRUCTURE;
- GALAXIES: X-RAYS