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| Title: |
Comparison of large-scale structures and velocities in the local universe
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| Author(s): |
Yahil, Amos
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| Abstract: |
Comparison of the large-scale density and velocity fields in the local universe shows detailed agreement, strengthening the standard paradigm of the gravitational origin of these structures. Quantitative analysis can determine the cosmological density parameter, Omega, and biasing factor, b; there is virtually no sensitivity in any local analyses to the cosmologial constant, lambda. Comparison of the dipole anisotropy of the cosmic microwave background with the acceleration due to the Infrared Astronomy Satellite (IRAS) galaxies puts the linear growth factor in the range beta approximately equals Omega (exp 0.6)/b = 0.6(0.7/-0.3) (95 confidence). A direct comparison of the density and velocity fields of nearby galaxies gives beta = 1.3 (0.7/-0.6), and from nonlinear analysis the weaker limit (Omega greater than 0.45 for b greater than 0.5 (again 95 confidence). A tighter limit (Omega greater than 0.3 (4-6 sigma)), is obtained by a reconstruction of the probability distribution function of the initial fluctuations from which the structures observed today arose. The last two methods depend critically on the smooth velocity field determined from the observed velocities of nearby galaxies by the POTENT method. A new analysis of these velocities, with more than three times the data used to obtain the above quoted results, is now underway and promises to tighten the uncertainties considerably, as well as reduce systematic bias.
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| NASA Center: |
Goddard Space Flight Center
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| Publication Date: |
July 1994
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| Document Source: |
Other Sources |
| No Digital Version Available: |
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| Document ID: |
19950034618
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| Accession ID: |
95A66217
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| Publication Information: |
Astrophysics and Space Science, 217, 1-2, p. 243-260, ISSN 0004-640X, Number of Pages = 18 |
| Contract-Grant-Task Number: |
NAG5-1228 |
| Keywords: |
BACKGROUND RADIATION; COSMOLOGY; DARK MATTER; GALACTIC EVOLUTION; GALAXIES; GRAVITATION; MICROWAVES; SKY SURVEYS (ASTRONOMY); UNIVERSE; VELOCITY; ASTRONOMICAL MAPS; BIAS; COMPARISON; DENSITY (NUMBER/VOLUME); INFRARED ASTRONOMY; INFRARED ASTRONOMY SATELLITE; PROBABILITY DISTRIBUTION FUNCTIONS; QUANTITATIVE ANALYSIS; RED SHIFT;
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| Notes: |
Science with astronomical near-infrared sky surveys; Les Houches School Workshop, Centre de Physique des Houches, Les Houches, France, Sep. 20-24, 1993 . A95-66166, p. 243-260 |
| Accessibility: |
Unclassified; Copyright; Unlimited; Publicly available; |
| Updated/Added to NTRS: |
2004-11-03 |
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