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Submillimeter Galaxies (SMGs)


Scientists have long pondered how extremely bright, ancient galaxies known as sub-millimeter galaxies (SMGs) managed to pump out stars 1,000 times faster than the Milky Way does today.

Two theories have dominated the debate. The first is that galaxy collisions drove short-lived, but spectacular bursts of star formation. The other idea is that SMGs are long-lived structures that accumulated mass over time.

“Neither scenario has been successful in fully replicating the observed properties of SMGs,” astronomer Romeel Dave, with the University of the Western Cape, Cape Town, South Africa, wrote in an essay in this week’s Nature.

A new study, also published Nature, details a computer simulation that,  for the first time,  matches observed properties of SMGs. The model shows that the galaxies aren’t transient and that they can generate stars at the incredible rate of 500 to 1,000 solar-mass stars PER YEAR for a billion years.

What makes them so productive? The simulation suggests the galaxies, which date back to about 3 billion years after the Big Bang,  tapped reservoirs of gas to form new stars, rather than rely on mergers with other galaxies.

“In a nutshell, the authors find that SMGs plausibly arise from a ‘perfect storm’ of high rates of gravitationally driven gas accretion, the recycling of previously ejected material and contributions to the systems’ submillimetre luminosity from nearby galaxies,” Dave wrote.

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