Researchers uncover chemical origins of the Perseus cluster of galaxies

An international team of researchers has developed new stellar and supernova models to explain the mysterious elemental abundance patterns left by billions of supernova explosions around the Perseus constellation, which have been difficult to explain with conventional theoretical models, reports three recent studies published in The Astrophysical Journal.

Deep within the Perseus Constellation lies one of the most massive structures known to science: The Perseus Cluster. A titan of the cosmos, it anchors over a thousand galaxies within a sea of superheated gas known as the Intracluster Medium (ICM). This gas, glowing fiercely in X-rays, acts as a celestial ledger, recording the chemical "fingerprints" left behind by billions of supernova explosions over billions of years.

However, data from the HITOMI (Astro-H) space telescope revealed a profound mystery. Long-standing theoretical models by researchers need important corrections. 

The observations showed levels of silicon, sulphur, argon, and calcium that simply did not match well to researchers' understanding of how massive stars at least ten times the mass of the Sun live and die. This discrepancy signaled a need to significantly rebuild the models of stellar evolution from the ground up.

A team of researchers, including The University of Tokyo Professor Emeritus and Kavli Institute for the Physics and Mathematics of the Universe (Kavli IPMU, WPI) Visiting Senior Scientist Ken'ichi Nomoto, Kavli IPMU Visiting Associate Scientist Shing-Chi Leung, and Netherlands Institute for Space Research Professor and Kavli IPMU Visiting Scientist Aurora Simionescu, has been working on the chemical abundances of Perseus Cluster measured by the X-ray Satellite HITOMI.

They published a sequence of papers in The Astrophysical Journal. The comprehensive multi-stage study first developed new models for massive stars that finally aligned with the specific chemical abundances (Si, S, Ar, and Ca) observed in the Perseus Cluster. 

Then, the team expanded this work, creating a massive catalog of star models spanning a wide range of masses (15 to 60 solar masses) and "metallicities", the initial chemical makeup of a star dictated by its age in the universe. By processing this catalog through a galactic chemical evolution pipeline, they were able to reconstruct an over 10-billion-year history of how supernova feedback has shaped the chemical patterns we see today.

In the third paper, the team considered the extreme case where a supernova explodes in a bipolar jet form. This happens when the stars are rotating, which results in a rapidly rotating black hole (aka Collapsar) or neutron stars. The accretion disk around the compact remnants is subject to magneto-rotational instability, which results in a very energetic jet firing towards the remaining stellar envelope. 

The team performed multi-dimensional simulations to trace how the jet triggered an outbreak and subsequent explosion. They discovered that its pronounced Zinc production could be the smoking gun for telling the fraction of these extreme events occurring in the past universe. 

The team will continue to study how the models affect the chemical evolution of the Milky Way galaxy across history, from which they can further study the supernova demography and stellar population. The team is also interested in studying the upcoming data release from XRISM on various galactic clusters.