Peek-a-boo! Astronomers spot 'T-Rex' of galaxies
By using the world's preeminent telescopes, astronomers peer behind a curtain of dust to find a giant star-making factory known as "Sparky."
If there's any one thing astronomers have mixed feelings about, it must be dust. On the one hand, cosmic dust can provide valuable information that can give clues to the origins of the universe, or to life on Earth. On the other hand, it can just plain get in the way.
In the case of a humongous galaxy that's been nicknamed "Sparky," a curtain of dust was doing the latter. But thanks to the infrared camera on the Hubble Space Telescope, along with the near infrared spectrograph at the Keck Observatory in Hawaii, astronomers were able to see beyond the dust -- and back through billions of years of time -- to spy a monster-sized galaxy in the process of being formed.
Because light from the distant galaxy takes so long to reach Earth, finding Sparky behind its cloud of gas provides scientists a glimpse back to a much more active time in the universe. "It's a formation process that can't happen anymore," said Erica Nelson, a Yale graduate student who is lead author of research recently published online in the journal Nature (PDF). "The early universe could make these galaxies, but the modern universe can't. It was this hotter, more turbulent place -- these were boiling cauldrons, forging stars."
According to the researchers, Sparky was formed about 11 billion years ago -- which is the age of the light we can now see from the giant star factory. That's about 3 billion years after the Big Bang. From their observations, and from calculations made from archival far-infrared images from the Spitzer and Herschel space telescopes, the astronomers have estimated that Sparky was spitting out 300 new stars annually as opposed to the Milky Way, which makes about 10 per year.
Nelson said in a NASA statement that the universe is now simply too spread out to allow such compact star-creation activity. "We suspect that this core-formation process is a phenomenon unique to the early universe because the early universe, as a whole, was more compact. Today, the universe is so diffuse that it cannot create such objects anymore." Indeed, Sparky measures about 6,000 light years across and holds about twice as many stars as the Milky Way, which measures about 100,000 light-years across.
Being able to see so far back in time through observing Sparky has allowed the astronomers to visually confirm a galaxy-formation theory that states that the "universe's heaviest galaxies develop from the inside out, forming their star-studded, central cores during early cosmic epochs," says the Yale report about the research. Until now that process had never been witnessed.
"Just like the hot oxygen-rich early Earth could produce dinosaurs, the hot, dense early universe could produce these galaxies," added Pieter van Dokkum, chair of Yale's Department of Astronomy. "As T-Rex was an extreme animal, these are extreme galaxies. They are tightly packed with stars and erupting with star formation."
Let's just hope no one decides to open a "Sparky" amusement park that seeks to recreate the galaxy. We all know how a similar idea ended last time.