Violent Youth Seeded The Universe With Iron
October 31, 2013

Vast Quantities Of Heavy Elements Were Created By Billions Of Exploding Stars

April Flowers for - Your Universe Online

The universe underwent a turbulent and violent youth more than 10 billion years ago, as evidenced by iron spread evenly between galaxies in one of the largest galaxy clusters in the Universe. This violent youth was responsible for seeding the cosmos with iron and other heavy elements that are critical to life itself, according to the new study published in Nature.

Scientists from the Kavli Institute for Particle Astrophysics and Cosmology (KIPAC), jointly run by Stanford University and the Department of Energy's SLAC National Accelerator Laboratory analyzed 84 sets of X-ray telescope observations from the Japanese-US Suzaku satellite to shed light on this important era. The research team paid particular attention to iron distribution throughout the Perseus cluster, a large grouping of galaxies approximately 250 million light-years away.

"We saw that iron is spread out between the galaxies remarkably smoothly," said Norbert Werner, an astrophysicist at KIPAC. "That means it had to be present in the intergalactic gas before the Perseus cluster formed."

The researchers say that the even distribution of these elements supports the theory that they were created 10 to 12 billion years ago. During this time of intense star formation, vast quantities of heavy elements were created by billions of exploding stars. During this time, black holes in the hearts of galaxies were also at their most energetic.

"The combined energy of these cosmic phenomena must have been strong enough to expel most of the metals from the galaxies at early times and to enrich and mix the intergalactic gas," said KIPAC graduate student Ondrej Urban.

The research team examined the Perseus cluster from eight different directions to settle the question of whether the heavy elements created by supernovae remain mostly in their home galaxies or are spread throughout intergalactic space. The hot, 10-million-degree gas that fills the spaces between galaxies was the focus of the study. They found the spectroscopic signature of iron reaching all the way to the cluster's edges.

The amount of iron in the cluster is roughly equivalent to the mass of 50 billion suns, according to the researchers estimations.

"We think most of the iron came from a single type of supernovae, called Type Ia supernovae," said former KIPAC member Aurora Simionescu, who is currently with the Japanese Aerospace Exploration Agency as an International Top Young Fellow.

An exploding star releases all of its material into the void in a Type Ia supernova. At least 40 billion Type Ia supernovae must have exploded within a relatively short period, cosmologically speaking, for that much iron to have been released and to have had the force to drive it out of the galaxies, according to the researchers.

Steven Allen, a KIPAC associate professor and head of the research team, said that the study findings indicate that the Perseus cluster is probably not unique and that iron and other heavy elements are evenly spread throughout all massive galaxy clusters.

"You are older than you think – or at least, some of the iron in your blood is older, formed in galaxies millions of light years away and billions of years ago," Simionescu said.

The team is continuing their research by looking for iron in other clusters and are eagerly awaiting a mission capable of measuring the concentrations of elements in the hot gas with greater accuracy.

"With measurements like these, the Suzaku satellite is having a profound impact on our understanding of how the largest structures in our universe grow," Allen said. "We're really looking forward to what further data can tell us."