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Cosmology A Research Briefing (1995) / Chapter Skim
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III. THE LARGE-SCALE STRUCTURE OF THE UNIVERSE
Pages 19-24

The Chapter Skim interface presents what we've algorithmically identified as the most significant single chunk of text within every page in the chapter.
Select key terms on the right to highlight them within pages of the chapter.


From page 19...
... A map of cosmic flows can be used to generate a map of the mass density distribution that caused them, including any dark matter between the galaxies. Such a map is shown in the upper pane!
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From page 20...
... Close to Earth, within 250 million light-years where flows are well measured, flow velocities have approximately the magnitude predicted if standard dark-matter theories employ the COBE measurements. This local agreement suggests that our basic model for structure formation, spanning many decades of length scale and depending on details of the nature of dark matter, is approximately correct.
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From page 21...
... On the other hand, the newer data on large-scale flows, which measure mass on scales 30 times larger than the older work, seem to suggest that the universe may contain sufficient density for closure (Q ~ 0.5 to 1~. This contradiction must be telling us something about the nature of the dark matter distribution.
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From page 22...
... Two additional quantities that affect the expansion are the cosmological constant, A, the vacuum energy density of the universe, and Q the ratio of the total mass/energy density in the universe to the critical density, which is required to just bring the expansion to a halt in the infinite future.
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From page 23...
... Extensive efforts in the 1960s and 1970s to study the apparent luminosity or size of distant objects, such as very luminous galaxies, were based on the hope that these objects were constant in brightness. These efforts were mostly abandoned after it was learned that the intrinsic luminosity of these standards probably changed significantly with time because of galaxy evolution.
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From page 24...
... Normal nearby galaxies emit most of their light at visible wavelengths, but the light received from the most distant galaxies is redshifted to infrared wavelengths. In the past decade, detectors with high sensitivity have been developed that are ideal for measuring weak infrared radiation, and the main technical problem that remains is the strong emission of infrared radiation from the atmosphere and from the telescope itself.
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Key Terms

  • dark matter
  • mass density
  • cosmic flow
  • hubble constant
  • distant galaxies

  • vacuum energy
  • energy density
  • luminous galaxies
  • structure formation
  • flow motions

  • velocity flows
  • gravitational instability
  • galaxy formation
  • mean mass
  • local tests

  • cosmic velocity
  • larger scales
  • hst observations
  • galaxy distribution
  • estimated ages

  • onto clusters
  • galaxies observed
  • eject energy
  • motions contains
  • study nearby

  • separate components
  • expansion rate
  • expand forever
  • recent results
  • tests extending


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