Seeds of life spread across the universe

Elements important for life on Earth are available in similar relative proportions throughout the bulk of the universe, a new survey of hot, X-ray-emitting gas in the Virgo galaxy cluster shows.
The elements needed to make stars, planets and people were evenly distributed across millions of light-years early in cosmic history, more than 10 billion years ago, researchers said.
The Virgo cluster, located about 54 million light-years away, is the nearest galaxy cluster and the second brightest in X-rays.
The cluster is home to more than 2,000 galaxies, and the space between them is filled with a diffuse gas so hot it glows in X-rays.

Using Japan's Suzaku X-ray satellite, a team led by Aurora Simionescu, an astrophysicist at the Japan Aerospace Exploration Agency (JAXA) in Sagamihara, acquired observations of the cluster along four arms extending up to 5 million light-years from its centre.
Different classes of supernovae produce different chemical compositions. Core-collapse supernovae mostly scatter elements ranging from oxygen to silicon, while white dwarf explosions release predominantly heavier elements, such as iron and nickel.

Once the chemical elements made by supernovae are scattered and mixed into interstellar space, they become incorporated into later generations of stars.
In an earlier study led by Norbert Werner, from the Kavli Institute for Particle Astrophysics and Cosmology (KIPAC) at Stanford University, Suzaku data showed that iron was distributed uniformly throughout the Perseus Galaxy Cluster, but information about lighter elements mainly produced by core-collapse supernovae was unavailable.

The Virgo Cluster observations supply the missing ingredients.
Simionescu and her colleagues showed they detect iron, magnesium, silicon and sulphur all the way across a galaxy cluster for the first time.
The elemental ratios are constant throughout the entire volume of the cluster and roughly consistent with the composition of the Sun and most of the stars in our own galaxy, researchers said.
The study shows that the chemical elements in the cosmos are well mixed, showing little variation on the largest scales.
The same ratio of supernova types - the same recipe - thought to be responsible for the solar system's makeup was at work throughout the universe.

"This means that elements so important to life on Earth are available, on average, in similar relative proportions throughout the bulk of the universe," said Simionescu.
The findings appear in The Astrophysical Journal Letters.