Galaxies during the era of reionisation in the early Universe (simulation)

Astronomers using ESO’s Very Large Telescope (VLT) have measured the distance to the most remote galaxy so far, UDFy-38135539, existing when the Universe was only about 600 million years old (a redshift of 8.6).At this early time, the Universe was not fully transparent and much of it was filled with a hydrogen fog that absorbed the fierce ultraviolet light from young galaxies. The transitional period when the fog was still being cleared by this ultraviolet light is known as the era of reionisation, illustrated with this still from a representative scientific simulation (see Alvarez et al. (2009) for more details).

When the Universe cooled down after the Big Bang, about 13.7 billion years ago, electrons and protons combined to form neutral hydrogen gas. This cool dark gas was the main constituent of the Universe during the so-called Dark Ages, when there were no luminous objects. This phase eventually ended when the first stars formed and their intense ultraviolet radiation slowly made the hydrogen fog transparent again by splitting the hydrogen atoms back into electrons and protons, a process known as reionisation. This epoch in the Universe’s early history lasted from about 150 million to 800 million years after the Big Bang. In this visualisation, ionised regions are blue and translucent, ionisation fronts are red and white, and neutral regions are dark and opaque.

The new study shows that the glow from UDFy-38135539 seems not to be strong enough on its own to clear out the hydrogen fog. There must be other galaxies, probably fainter and less massive nearby companions of UDFy-38135539, which also helped make the space around the galaxy transparent.

Crédit:

M. Alvarez (http://www.cita.utoronto.ca/~malvarez), R. Kaehler, and T. Abel/ESO

À propos de l'image

Identification:eso1041a
Type:Simulation
Date de publication:20 octobre 2010 19:00
Communiqués de presse en rapport:eso1041
Taille:2220 x 1607 px

À propos de l'objet

Nom:UDFy-38135539
Type:Early Universe : Galaxy
Catégorie:Galaxies

Formats des images

Grand JPEG
898,5 Kio
JPEG taille écran
289,3 Kio

Zoomable


Fonds d'écran

1024x768
340,5 Kio
1280x1024
460,1 Kio
1600x1200
600,1 Kio
1920x1200
647,1 Kio
2048x1536
830,2 Kio

Couleurs & filtres

DomaineTélescope
Very Large Telescope