Infall velocity toward virgo, the hubble constant, and a search for motion toward the microwave background

Journal Article · Mon Jul 01 04:00:00 EDT 1985 · Astrophys. J.; (United States)

DOI:https://doi.org/10.1086/163277· OSTI ID:5265591

Tammann, G A; Sandage, A

From data on distance ratios of eight clusters and groups of galaxies in the velocity interval 800--2000 km s/sup -1/, the infall of the Local Group toward the Virgo Cluster center due to the overdensity of the Virgo complex is determined to be v/sub vc/ = 200 +- 50 km s/sup -1/, in agreement with many previous high-weight determinations. If all mass in the universe is clustered like galaxies, this low infall velocity gives a mean mass-to-light ratio of M/L/sub B/roughly-equal70 averaged over the galaxies in the Virgo complex that lie within the sphere whose center is the Virgo Cluster core and whose periphery is at the Local Group. This is much lower than M/L/sub B/ roughly-equal400 required in the cluster core, showing that dark matter in the core cannot extend into the cluster envelope unless v/sub vc/ does not, in fact, measure the true over density because of dark matter of a second type, more uniformly distributed. But, if such matter does not exist, the generally observed monotonic increase of M/L with scale length is halted at scales of < or approx. =10 Mpc, at which point it turns drastically downward. Correcting the observed velocities of each of the eight test groups for their individual infalls using an idealized Virgocentric flow model gives a mean Hubble ratio for these galaxies of H/sub 0/ = 52 +- 2 km s/sup -1/ Mpc using a Virgo distance of 21.6 Mpc (m-M = 31.7). This defines the '' free'' expansion within the Virgo complex itself, corrected for the effects of Virgocentric deceleration. The value of H/sub 0/ (free Virgo) will scale linearly for other assumed Virgo distances.

• Research Organization: Astronomisches Institut der Universitaet Basel; and European Southern Observatory
• OSTI ID: 5265591
• Journal Information: Astrophys. J.; (United States), Journal Name: Astrophys. J.; (United States) Vol. 294:1; ISSN ASJOA
• Country of Publication: United States
• Language: English

Related Subjects

640106* -- Astrophysics &amp; Cosmology-- Cosmology
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
COSMOLOGY
DISTANCE
GALAXIES
GALAXY CLUSTERS
HUBBLE EFFECT
LUMINOSITY
MASS
OPTICAL PROPERTIES
PHYSICAL PROPERTIES
RED SHIFT
VELOCITY