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An effect seen in the spectra of quasars with redshift greater than 6 that is explained as due to absorption of quasar emission due to neutral hydrogen (hydrogen atoms). The effect exists because intergalactic hydrogen should absorb photons with energies redshifted into the Lyman series at different points along the line of sight.

Nearby quasars and galaxies show no such absorption indicating that the material between the galaxies at recent times is ionized. Quasars with redshift greater than 6 show a depression between the hydrogen lines of the quasar to a region with about a redshift of 6. This suggests that the material in the very early universe was not completely ionized.

As of 2004, the time of reionization as seen by Gunn-Peterson appears to conflict with the estimates of the electron column density as measured by WMAP.

This effect was proposed by Gunn and Peterson in 1965 and was first observed in quasars discovered by the Sloan Digital Sky Survey in 2001.

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Topics: Gunn-Peterson Trough, Gunnies, Gunn (Valkyrie), Gunnlod...

GunniesGunnies is a mining term derived from the Cornish language. It refers to open-cast mines. An example is to be found at Porthtowan near St Agnes in Cornwall. The word can also mean the empty space left by removing the lode from a mine, or the width of this	Gunn (Valkyrie)In Norse mythology, Gunn was one of the Valkyries. Together with Rota and Skuld she attended the battle fields and chose those who were to be slain and taken to Valhalla. She is mentioned on the Rok Stone and in Snorri Sturluson's Edda. Sa hon valkyrjur v	GunnlodIn Norse mythology, Gunnlod was a daughter of Suttung, who was set guard by her father in the cavern where he housed the mead of poetry. She was tricked by Odin, who stole all the mead. Norse giants.
GunnersburyGunnersbury is a place in West London, England in the London Borough of Hounslow. Chiswick Kew Acton Brentford Mortlake Nearest tube stations: Chiswick Park tube station Gunnersbury tube station Nearest railway station: South Acton railway station London	Gunnison County, ColoradoGunnison County is a county located in the U. state of Colorado. As of 2000, the population is 13,956. The county seat is Gunnison. Geography According to the U. Census Bureau, the county has a total area of 8,443 km² (3,260 mi²). 8,388 km² (3,239 mi²) of	Gunnison, ColoradoGunnison is a city located in Gunnison County, Colorado. As of the 2000 census, the city had a total population of 5,409. It is the county seat of Gunnison County 6. Geography Gunnison is located at 38°32'45" North, 106°55'54" West (38. 545838, -106.
Gunnison, Mississippi	Gunn City, Missouri	Gunnison, Utah
Gunnerales	Gunnar Helén	Gunnery Sergeant
Gunnera	Gunnar Hansen	Gunnison River

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