Searching for the first Stars

Recently, astronomers found two immense clouds of pristine gas, nearly 12 billion light years away -- clouds that astronomers suspect are the stuff from which the first stars were born. The Kavli Foundation spoke with three prominent researchers about this and other exciting findings that are moving scientists closer to understanding how the first stars and galaxies formed. This includes the realization that in early times, there were many more small, feeble galaxies than large luminous galaxies. 

This artist's concept shows what the very early universe might have looked like, just after its first stars began bursting onto the scene [Credit: NASA/JPL-Caltech/R. Hurt (SSC)]

"If you were to take a space ship and go back to that point in cosmic time, you'd find that the sky is really ablaze with them -- so many of them that their combined output is very significant," said Richard Ellis, Steele Professor of Astronomy at the California Institute of Technology. "These early objects are in fact very, very small -- about a tenth the diameter of the Milky Way. And yet, they are forming stars more prodigiously than the galaxy we live in today." 

Discoveries such as these come as scientists focus on studying the gaseous "fingerprints" the early galaxies left on their surroundings -- what's called the intergalactic medium (IGM). "We know from these observations that after about one billion years all of this gas is ionized, and it's the galaxies that we think did this," said George Becker, Fellow, the Kavli Institute for Cosmology at the University of Cambridge. "The question that we are trying to answer is how and when it happened, and what these earliest galaxies were like." 

Said Avi Loeb, Chair of the Department of Astronomy and Director of the Institute for Theory and Computation, Harvard University, "If we can map the distribution of galaxies and the hydrogen gas between them, in the IGM, we can see the relationship between the places where the galaxies are and the regions that were ionized… [This] gives us indirect evidence for the earliest galaxies. This new technique will enable us to directly study the galaxies that ionized that hydrogen gas." 

And what do researchers ultimately hope to uncover? 

"[We] would like to understand how the galaxies that we see around us, including the Milky Way, came into existence," said Loeb. "It's going back in time to our origins, in a sense. Religious texts try to address these questions, but now we are able to come up with a scientific version of the story of Genesis." 

For the full discussion visit: http://www.kavlifoundation.org/science-spotlights/searching-first-stars 

Source: Kavli Foundation via Newswise [February 28, 2012]