No one has ever seen an object further away than the one at the center of the image below. It’s a gamma-ray burst known as GRB 090423, spotted by the Swift satellite on April 23rd and quickly observed by the Gemini Observatory and United Kingdom Infrared Telescope, both on Mauna Kea (Hawaii). The source is visible at longer wavelengths but disappears at the 1 micron level, all of which corresponds to a distance of about thirteen billion light years.
Image: The fading infrared afterglow of GRB 090423 appears in the center of this false-color image taken with the Gemini North Telescope in Hawaii. The burst is the farthest cosmic explosion yet seen. Credit: Gemini Observatory/NSF/AURA, D. Fox and A. Cucchiara (Penn State Univ.) and E. Berger (Harvard Univ.)
Spectacular, no? Numerous telescopes around the planet went on to observe the GRB’s afterglow, allowing the infrared light’s spectrum to confirm the highest redshift ever measured: z = 8.2.
The object in question was probably a massive star reaching the end of its life, its core collapsing into a black hole or neutron star. In the process, jets of gas punch out of the star and encounter gases previously shed during the star’s senescence, heating them up to produce the short afterglows that can be seen in various wavelengths. The visible light of the event was absorbed by hydrogen gas in the early universe, but the infrared glow was bright indeed, given that the light we see in the image has been traveling for most of the 13.7 billion year age of the universe.
Edo Berger (Harvard Smithsonian Center for Astrophysics) notes the significance of the find:
“I have been chasing gamma-ray bursts for a decade, trying to find such a spectacular event. We now have the first direct proof that the young universe was teeming with exploding stars and newly-born black holes only a few hundred million years after the Big Bang.”
Take a look at this second image, which places the GRB in perspective.
Image: Distribution of redshifts and corresponding age of the Universe for gamma-ray bursts detected by NASA’s Swift satellite. The new GRB 090423 at a redshift of z = 8.2 easily broke the previous record for gamma-ray bursts, and also exceeds the highest redshift galaxy and quasar discovered to date, making it the most distant known object in the Universe. GRB 090423 exploded on the scene when the Universe was only 630 million years old, and its light has been travelling to us for over 13 billion years. Credit: Edo Berger (Harvard/CfA).