The spectrum of the quasar PKS 1251-407

The spectrum of the quasar PKS 1251-407 (in red) is compared to the observations done by GROND in the seven different passbands (in green). The close agreement between the GROND data and the spectrum shows the strength of the photometric redshift technique. The large decrease in the flux in the blue part of the spectrum (around 500 nm) is the so-called Lyman drop-out and is what allows to determine the distance of the object. In this case, the Lyman-alpha line of atomic hydrogen (rest wavelength 121.6 nm) is observed at around 660 nm, i.e. in the red spectral region, indicating a redshift of 4.46, or a distance of 12.3 billion of light-years. Light from this object started its long journey towards us less than 1.4 billion years after the Big Bang.

Crediti:

ESO

Riguardo l'immagine

Identificazione:eso0730c
Tipo:Osservazione
Data di rilascio:06 Luglio 2007
Notizie relative:eso0730
Grandezza:953 x 646 px

Riguardo all'oggetto

Nome:PKS 1251-407
Tipo:Early Universe : Galaxy : Activity : AGN : Quasar
Distanza:z=4.46 (spostamento del rosso)
Categoria:Cosmology
Quasars and Black Holes

Formati delle immagini

JPEG grande
97,6 KB

Colori e filtri

BandaTelescopio
InfrarossoMPG/ESO 2.2-metre telescope
GROND
OtticoMPG/ESO 2.2-metre telescope
GROND