Sky surveys and baryon acoustic oscillations Dark matter

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baryon acoustic oscillations (bao) regular, periodic fluctuations in density of visible baryonic matter (normal matter) of universe. these predicted arise in lambda-cdm model due universe s acoustic oscillations in photon-baryon fluid , can observed in cosmic microwave background angular power spectrum. baos set preferred length scale baryons. dark matter , baryons clumped after recombination, effect weaker in galaxy distribution in nearby universe, detectable subtle (~ 1 percent) preference pairs of galaxies separated 147 mpc, compared separated 130 or 160 mpc. feature predicted theoretically in 1990s , discovered in 2005, in 2 large galaxy redshift surveys, sloan digital sky survey , 2df galaxy redshift survey. combining cmb observations bao measurements galaxy redshift surveys provides precise estimate of hubble constant , average matter density in universe. results support lambda-cdm model.








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