Update
Show Summary Details

Page of

PRINTED FROM OXFORD REFERENCE (www.oxfordreference.com). (c) Copyright Oxford University Press, 2023. All Rights Reserved. Under the terms of the licence agreement, an individual user may print out a PDF of a single entry from a reference work in OR for personal use (for details see Privacy Policy and Legal Notice).

date: 28 February 2024

selection function 

Source:
The Oxford Companion to Cosmology
Author(s):

Andrew Liddle,

Jon Loveday

Most astronomical surveys select objects by their observed flux (or equivalently, apparent magnitude). Since observed flux decreases as the square of distance, only the most intrinsically luminous objects will appear at large distance in such a survey, and, since such luminous objects are rare, the overall space density of objects decreases with distance. The selection function of a survey gives the probability that an object within a given luminosity range will be included in the survey, as a function of distance or redshift. The selection function generally decreases smoothly from one at low redshift, where all objects in the luminosity range will be included, to zero at large redshift, where there are no objects of sufficiently high luminosity to be included.... ...

Access to the complete content on Oxford Reference requires a subscription or purchase. Public users are able to search the site and view the abstracts and keywords for each book and chapter without a subscription.

Please subscribe or login to access full text content.

If you have purchased a print title that contains an access token, please see the token for information about how to register your code.

For questions on access or troubleshooting, please check our FAQs, and if you can''t find the answer there, please contact us.