In the early Universe, there were 1,000 times more star-forming galaxies than today. By measuring how far these starburst galaxies are from Earth, astronomers can better understand how soon after the Big Bang the Universe started making new stars. Until now, it has been difficult to pinpoint how far away these galaxies really are.
Image above: ALMA images of gravitationally lensed, distant star-forming galaxies. Credit: ALMA (ESO/NRAO/NAOJ), J. Vieira et al.
Using the new Atacama Large Millimeter/submillimeter Array (ALMA) telescope, located in Chile, a team of scientists from Canada, USA, Europe and Australia has now been able to measure more precisely the distance of several star-forming galaxies and, in doing so, has discovered that some are even farther away than previously believed.
“By determining how distant these galaxies are from Earth, we have been able to show that huge bursts of star formation happened when the Universe was quite young,” says team member and CIFAR Fellow Gilbert Holder (McGill). “The information from ALMA provides a snapshot of how the massive galaxies that we see around us today formed over time.”
The team, which also included Global Scholar Keith Vanderlinde (University of Toronto) and Fellow Matt Dobbs (McGill), published their findings on March 13, 2013, in the journal Nature.
The galaxies were first discovered by the team using the South Pole Telescope (SPT) and then analyzed more closely with ALMA. ALMA – the largest ground-based astronomical project in the world – is made up of high-precision antennas that capture light at tiny wavelengths, offering astronomers a finer look into the Universe.
“When we first discovered these galaxies using SPT, we couldn’t understand why so many of them were so bright,” says Holder. “CIFAR meetings were a place for us to bounce ideas around informally, and it was here that another CIFAR member, Carlos Frenk, shared with me his detailed models of galaxy brightness. We started using and adapting these models to inform our decisions about how far away galaxies are.”
The team looked at a sample of bright galaxies and found that 10 of them were forming stars when the Universe was just less than 2 billion years old. Two galaxies were even more distant, meaning they were creating stars just one billion years after the Big Bang.
These discoveries offer scientists a clearer timeline of what was happening in the Universe after the Big Bang. The galaxies will now be key targets for studying the physics of star formation.
Partners and funders for this work included the: National Science Foundation (USA), Kavli Foundation, Gordon and Betty Moore Foundation, European Southern Observatory, National Institutes of Natural Sciences (Japan), National Research Council (Canada), National Science Council (Taiwan), Academia Sinica Institute of Astronomy and Astrophysics (Taiwan), Associated Universities, Inc., National Radio Astronomy Observatory (USA), National Astronomical Observatory of Japan, NASA, European Space Agency, Natural Sciences and Engineering Research Council of Canada, Canada Research Chairs program, and CIFAR.