Definition of Volume Limited Sample for Sky Surveys

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SUMMARY

A volume limited sample in the context of sky surveys refers to a selection of galaxies that are included based on their brightness within a specific redshift range. This approach ensures that only galaxies meeting defined brightness criteria are considered, effectively filtering out fainter galaxies that may be missed due to observational limitations. The distinction between absolute and apparent brightness is crucial; a true volume limited sample is defined by absolute brightness, while apparent brightness does not qualify as such.

PREREQUISITES
  • Understanding of redshift in astronomy
  • Familiarity with galaxy cataloging techniques
  • Knowledge of absolute vs. apparent brightness
  • Basic concepts of sky surveys and observational limitations
NEXT STEPS
  • Research the methodology of constructing volume limited samples in galaxy surveys
  • Study the implications of redshift on galaxy visibility and cataloging
  • Learn about the differences between absolute and apparent brightness in astronomical contexts
  • Explore specific sky surveys that utilize volume limited samples, such as the Sloan Digital Sky Survey (SDSS)
USEFUL FOR

Astronomers, astrophysicists, and researchers involved in galaxy surveys and cosmological studies will benefit from this discussion.

Zaphodx57x
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Does anybody have a link to a precise definition of a "volume limited sample." This pertains especially to sky surveys that catalog galaxies. Due to limited precision, surveys tend to miss fainter galaxies as redshift increases. Thus, very loosely, I think, a volume limited sample filters out certain galaxies so that only galaxies of a finite brightness range are considered at all pertinent redshifts. However, I am looking for a precise definition, but can't seem to find one.
 
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A volume limited sample just takes galaxies within a certain redshift range.

Zaphodx57x said:
Thus, very loosely, I think, a volume limited sample filters out certain galaxies so that only galaxies of a finite brightness range are considered at all pertinent redshifts.

Do you mean absolute or apparent brightness? If the latter, this is not a volume limited sample.
 

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