Latest news with #AndraStroe
Gizmodo
7 hours ago
- Science
- Gizmodo
These Two Galaxy Clusters Are About to Smash Into Each Other—Again
Roughly 2.8 billion light-years from Earth, two galaxy clusters are engaged in a cosmic tussle. These enormous structures last collided about a billion years ago, but now, it appears they're going back for round two. The galaxy clusters involved in this scuffle are part of a larger system—a 'combined' galaxy cluster—called PSZ2 G181. In a study published in The Astrophysical Journal in April, researchers analyzed new observations of PSZ2 G181 that suggest its constituent clusters are poised to smash into each other for a second time. Major collisions between galaxy clusters are generally considered rare, according to the European Space Agency (ESA), but repeated collisions are decidedly more unusual. What's more, PSZ2 G181's total mass is uncharacteristically low compared to other combined galaxy clusters that have resulted from collisions, adding another layer of peculiarity to the findings. Astronomers know the individual galaxy clusters that make up PSZ2 G181 crashed into each other once before thanks to previous radio observations, according to a NASA statement. That work revealed parentheses-shaped regions of diffuse radio emissions on the outskirts of the system. These structures most likely formed as a result of the initial collision a billion years ago. This new study, led by Andra Stroe, a postdoctoral fellow at the Harvard & Smithsonian Center for Astrophysics, further validates the idea that a previous collision occurred. The researchers analyzed new observations of PSZ2 G181 from two X-ray observatories—NASA's Chandra and the European Space Agency's XMM-Newton. Their study identified a bridge of cool gas connecting the two clusters, which probably resulted from gas stripping during the first collision, according to their report. Over the last billion years, the two clusters have drifted apart and now sit roughly 11 million light-years away from each other. This is the largest separation between these kinds of structures that astronomers have ever seen, according to NASA's statement. But Stroe and her colleagues found evidence to suggest these galaxy clusters are now on a collision course again. The team uncovered three more shock fronts aligned with the previous axis of collision—a potential early sign of a second, oncoming crash. The discovery of this rare event provides new insight into the dynamics of merging galaxy clusters—particularly those involving low-mass systems, which are underexplored. As the researchers note, finding radio emissions from low-mass clusters like PSZ2 G181 is challenging, but 'with the advent of new-generation radio telescopes and surveys, we may be uncovering the 'tip of the iceberg,' they state in their report.
NDTV
a day ago
- Science
- NDTV
Two Galaxy Clusters That Collided Previously Are All Set To Smash Again
Two galaxy clusters that previously collided are now heading for another round of cosmic headbutt, NASA's Chandra X-ray Observatory and other telescopes have found. Located 2.8 billion light years from Earth, each of the two galaxy clusters contain thousands of galaxies, vast quantities of dark matter and superheated gas. The two colliding clusters, together known as PSZ2 G181, resemble an irregular violet peanut shell with bulbous ends linked by a tapered middle. A composite image of the cosmic event shows crescent-shaped structures surrounding the system. As per the astronomers, these are likely shock fronts, described as massive, sonic-boom disturbances, often located near a dense core remnant. The shock fronts created from the initial impact have since moved apart and are now about 11 million light-years away from each other - the widest separation ever recorded. This suggests just how massive and long-lasting the effects of galaxy collisions can be. "Bracketing the combined galaxy cluster, these shock fronts were caused by the initial collision about a billion years ago. They are currently separated by 11 million light-years," NASA stated. Despite their enormous distance, the galaxy clusters are gravitationally bound and slowly turning back for another high-speed impact. "Now, data from NASA's Chandra and ESA's XMM-Newton is providing evidence that PSZ2 G181 is poised for another collision. Having a first pass at ramming each other, the two clusters have slowed down and begun heading back toward a second crash." As per Andra Stroe, the lead author of the study, the second encounter offers scientists the chance to observe a lower-mass system undergoing the kind of large-scale violence typically seen in more massive clusters. Additionally, the collision could provide more insights into the mysterious unseen substance known as dark matter, as well as the evolution of the universe.
