Much of the Universe appears to be unchanged during the course of a human lifetime. But that’s a fallacy; things are constantly shifting, and as a result, galaxies and the clusters they reside in can become quite chaotic environments as a result of mergers and collisions.
Some galaxy clusters, nevertheless, appear to be considerably calmer than others.
Massive structures known as galaxy clusters can house hundreds of individual galaxies, enormous gas clouds, and tremendous amounts of dark matter. The Virgo Supercluster, which has more than 100 galaxy groupings and clusters, includes our Milky Way galaxy. Additionally, the Laniakea Supercluster includes the Virgo Supercluster. There will always be Matryoshka Doll comparisons with these stacked arrangements.
Through the merger of individual galaxies, groups, and even other clusters, galaxy clusters expand over time. The emerging clusters bear the scars of this tumultuous process.
However, some clusters are regarded as “relaxed,” which means they don’t exhibit symptoms of mergers. Recently, researchers discovered SPT2215, the most remote relaxed cluster to date. Astronomers are viewing it as it was when the Universe was only 5.3 billion years old. It is located about 8.4 billion light years away. Although relaxed galaxy clusters had previously been discovered, they have never been this remote or this old.
The primary author of a report on the cluster, Michael Calzadilla of the Massachusetts Institute of Technology (MIT), said, “Until now, we have not seen a relaxed galaxy cluster as distant as SPT2215.” The discovery and many critical aspects of the cluster and neighboring clusters are covered in three papers, with that one being the most recent.
The three papers are:
SPT-CL J2215-3537: A Massive Starburst at the Center of the Most Distant Relaxed Galaxy ClusterThe SPTpol Extended Cluster Survey
Cosmological constraints from gas mass fractions of massive, relaxed galaxy clusters
The fact that SPT2215 has only one galaxy at its center is another one of its peculiar characteristics. Within 600,000 light-years, there are no additional elongated or brilliant galaxies. This provides fresh proof that, at least during the previous billion years, the cluster hasn’t undergone any recent mergers.
The fact that this cluster is so massive, so early in the universe, suggests a really exciting, fast formation history.
Lindsey Bleem, U.S. Department of Energy’s Argonne National Laboratory
High-evolved massive elliptical galaxy SPT2215’s central galaxy is isolated. It is often referred to as a BCG, or brightest cluster galaxy. They are the most prominent galaxy in a group of galaxies. BCGs are some of the most massive and brightest galaxies in our time period. Its presence and properties also suggest that the cluster is unhurried and that the majority of its growth occurred during the early phases of the universe’s evolution.
“The high mass of this cluster, coupled with the fact that it is dynamically relaxed with a highly isolated BCG, suggests that it is an exceptionally rare system that must have formed very rapidly in the early universe,” the authors write in their research.
Leaving aside the strange nature of the cluster, astronomers can learn something from it about a persistent problem in astrophysics: the contribution of black hole feedback to star formation.
An active galactic nucleus is a supermassive black hole that is actively accreting matter and ejecting strong energy jets. Astrophysicists do not fully comprehend the jets of energy, nor do they know how the accretion is initiated or stopped. Illustris TNG simulations indicate that a large portion of the hot material can cool quite quickly and allow stars to form, but they are not definitive.
Gas filaments can be seen extending from the BCG in the Hubble image in the upper panel to a distance of around 20 kiloparsecs. Deeper observations will show their full scope, which may extend even beyond. In essence, these filaments are extended nebulae where newborn stars are illuminating the gas with intense radiation. They provide compelling evidence of high rates of star creation. The authors write in their research, “Filamentary nebulae like these typically signal regions of ionization by young stars and can be seen in many other strong cooling clusters.”
The size of the cluster itself is the discovery’s biggest selling point, though. For it to be that large and at ease, it must have quickly formed.
“The fact that this cluster is so massive, so early in the universe, suggests a really exciting, fast formation history,” said Lindsey Bleem of the Argonne National Laboratory of the U.S. Department of Energy. In the first of the three new studies, published in 2020, Bleem and colleagues initially described identifying the cluster. “However, the fact that it is relaxed hints at the contrary. It would be like coming home to a clean kitchen after dinner rush.
The James Webb Space Telescope’s observations and these new observations are complementary. The JWST discovered that the early galaxies of the universe were significantly more thoroughly formed than previously believed. One researcher hypothesized that the Universe is twice as ancient as previously believed as a result of these JWST discoveries, yet the study making this claim hasn’t received much attention.
We’ve somehow been misinformed about how quickly galaxies develop and evolve, and how they, along with the clusters they belong to, become so big. We are now even more uncertain about our understanding as a result of SPT2215’s observations.
Another contribution to our understanding of the universe comes from relaxed clusters. They serve as markers and gauges for the Universe’s expansion and its underlying source of dark energy.
According to Adam Mantz of Stanford University, who discovered SPT2215’s relaxed status using Chandra data in 2022, “Relaxed clusters like SPT2215 are one of the signposts that have been used to measure the expansion of the universe.” We are able to more precisely constrain the rapidity of the cosmic expansion and the characteristics of the dark energy that powers it by include far-off objects like these in our sample of relaxed clusters.
More:
- Press Release: Unexpectedly Calm and Remote Galaxy Cluster Discovered
- New Research: SPT-CL J2215?3537: A Massive Starburst at the Center of the Most Distant Relaxed Galaxy Cluster
- Universe Today: Protogalaxy Cluster Found When the Cosmic Fog Was Starting to Clear, When the Universe Was Just 750 Million Years Old
