Must the disk and halo dark matter be different?

Abstract

view Abstract Citations (29) References (26) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Must the Disk and Halo Dark Matter Be Different? Lake, George Abstract There are two dark matter problems in the Galaxy. In addition to the dark halo known to exist in other galaxies, half of the mass of the disk is unaccounted for. The local density of dark matter in the galactic disk is 10-20 times that of the dark halo. I argue that these need not be two different kinds of dark matter. If the dark halo was initially composed of lumps resembling present-day dwarf galaxies, these lumps behaved like "sinking satellites" and some fraction of them settled into the disk. The required amount of matter took 2-3 Gyr to be dragged into the disk by the action of dynamical friction. Roughly 70%-80% of the local material would be in direct orbits, having velocities very close to the local circular velocity and hence a velocity difference with respect to the Earth of approximately the velocity dispersion of the old disk. However, roughly 20%-30% of such matter would be in retrograde orbits having a relative velocity of nearly 500 km s^-1^. If the disk and halo matter are made of the same material, the disk dark matter will dominate the signal in proposed dark matter detection schemes. Publication: The Astronomical Journal Pub Date: November 1989 DOI: 10.1086/115238 Bibcode: 1989AJ.....98.1554L Keywords: Dark Matter; Disk Galaxies; Galactic Mass; Halos; Milky Way Galaxy; Black Holes (Astronomy); Dwarf Galaxies; Hubble Constant; Astrophysics; GALAXIES: THE GALAXY full text sources ADS |