Hot on the heels of Monday’s cosmic search engine is news from Caltech that images of the oldest known galaxies have been obtained. These heavenly bodies existed at a time when the universe was a mere 500 million years old, some 13 billion years ago.
Caltech astronomer Richard Ellis exploited “gravitational lensing”, an effect by which light from distant stars and galaxies is focused towards us by intervening massive objects. Ellis presented his images of these faint and distant objects today at a conference entitled “From IRAS to Herschel and Planck” being held conference at the Geological Society in London.
The Caltech-led group used massive clusters of galaxies, as the most powerful gravitational lenses around to locate galactic systems more distant than any previously observed. They used the Keck II 10 m diameter reflector telescope on Mauna Kea, Hawaii, to make their observations.
The resulting images can be seen on the Caltech site. These galaxies represent the earliest seen twinklings of the universe following the so-called Dark Ages before which no stars shone. Pinpointing the moment of “cosmic dawn” is one of the major quests of modern astronomy.
Of course, the observations may not be definitive, confesses Ellis. “As with all work at the frontiers, skeptics may wish to see further proof that the objects we are detecting with Keck are really so distant,” he explains.
“We can infer the Universe had a lot of star formation at these early times from Spitzer Space Telescope measurements of larger galaxies seen when the Universe was about 300-500 million years older”, explains Mr Stark. “These galaxies show the tell-tale sign of old stars (and were described in earlier work by University of Exeter scientist Andrew Bunker). To produce these old stars requires significant earlier activity, most likely in the fainter star-forming galaxies we have now seen.”