Space scientists have discovered some of the brightest distant galaxies ever found, playing hide and seek in clouds of cosmic dust. The brilliant cities of stars lie close to the edge of the known universe and are so far away that their light has taken 12 billion years to reach us across space.
They were virtually invisible to the powerful Hubble space telescope because of the blocking dust and gas. But astronomers combined optical and radio telescopes to force the galaxies to break cover.
Their powerful tools included the heat-seeking Spitzer space telescope which views objects in the infrared part of the spectrum.
Last month, astronomers from California reported that they had spotted the most distant galaxies ever observed from Earth. And Spitzer has already recorded objects forming in the earliest days of the universe.
The latest team of astronomers, from the Harvard-Smithsonian Centre for Astrophysics in Massachusetts, say they are seeing the galaxies as they existed when the universe was less than two billion years old, compared to its current age of around 14 billion years.
They are surprised by their brightness because smaller, dimmer galaxies were more common in the early universe because it took time for them to grow.
Astronomer Giovanni Fazio said: “It’s a real surprise to find galaxies that massive and luminous existing so early in the universe. We are witnessing the moment when the most massive galaxies in the universe were forming most of their stars in their early youth.”
Colleague Josh Younger said: “It’s tough to explain how such bright, massive, dusty galaxies formed so early in the lifetime of the universe.”
The discovery team first spotted the distant galaxies with the AzTEC imaging camera on the James Clerk Maxwell Telescope on Hawaiii. The camera discovered several hundred previously unseen, luminous galaxies. The astronomers made follow-up observations of the seven brightest galaxies, confirming that they were single objects and not several fainter ones seen together.
Once their precise positions were measured, additional observations were made with the Hubble Space Telescope, the Spitzer Space Telescope, and the Very Large Array of radio telescopes. Hubble found almost no sign of them, because of the veils of dust and gas, and the Very Large Array detected only the two closest galaxies. View the original press release here. Remember, too, that you can study distant galaxies for yourselves and help astronomers at the amazing Galaxy Zoo.
The image shows one of the galaxies as revealed, from left, by the AzTEC submillimeter camera, by the high resolution of the Smithsonian’s Submillimeter Array, and in visible light by Hubble. Credit: Left – UMass Amherst / Middle – Harvard-Smithsonian CfA / Right – COSMOS/ACS Team.