Astronomers have found a long-missing component of a galactic collision involving the Perseus galaxy cluster, positioned 240 million light-years from Earth.
This component, a newly detected “subcluster,” is 1.4 million light-years to the west of NGC 1275, the central galaxy of the Perseus cluster. These two parts appear to be linked by a faint “bridge” of fabric.
The structural spine of this bridge is darkish matter, the universe’s most mysterious “stuff.” Darkish matter stays successfully invisible by not interacting with gentle, however its interplay with gravity has helped to form galactic constructions.
“That is the lacking piece we have been in search of,” staff member James Jee mentioned in an announcement. “All of the odd shapes and swirling gasoline noticed within the Perseus cluster now make sense throughout the context of a serious merger.”
Galaxy clusters are a few of the largest constructions within the identified universe, consisting of hundreds of galaxies sure collectively by gravity.
Scientists have lengthy believed that these clusters develop by means of high-energy mergers that might be a few of the strongest occasions within the cosmos since the Large Bang.
With a mass equal to round 600 trillion suns the Perseus cluster has lengthy been thought-about to be the “poster baby” for galaxy clusters. Nonetheless, this mannequin galaxy cluster has been missing is the telltale signatures that time towards its development by way of merger.
That was, till now.
The poster-child for galaxy clusters has a violent historical past
To sort out this thriller, Jee and colleagues used the Subaru Telescope and its Hyper Suprime-Cam to probe deeper into the Perseus than ever earlier than.
This investigation hinged on a phenomenon referred to as “gravitational lensing,” first predicted by Albert Einstein in his 1915 magnum opus concept of gravity often known as “normal relativity.“
Normal relativity states that objects with mass trigger the very cloth of spacetime (the 4D unification of area and time) to warp, with gravity arising from this curvature.
When gentle from a background object passes by means of spacetime warped by a large physique, like a cluster of galaxies, its path is curved. This may trigger the sunshine to be amplified, thus magnifying that background physique, therefore the time period “lensing.”
This impact may also reveal issues in regards to the lensing physique, together with its construction. And since darkish matter has mass and due to this fact warps area and diverts gentle by means of its gravitational affect, lensing may also reveal the distribution of a gravitational lens’ darkish matter content material.
On this case, that course of revealed the presence of a large “clump” of darkish matter within the Perseus cluster weighing in at 200 trillion photo voltaic lots. This clump is linked to the core of the Perseus cluster by a a lot lighter however vital darkish matter bridge.
The staff carried out simulations of the Perseus cluster, which revealed that this clump collided with the cluster round 5 billion years in the past. What stays of this cluster is nonetheless sculpting the Perseus cluster at this time.
“This breakthrough was made doable by combining deep imaging knowledge from the Subaru Telescope with superior gravitational lensing strategies we developed — demonstrating the facility of lensing to unveil the hidden dynamics of the universe’s most large constructions,” Jee concluded.
The staff’s analysis was printed on Wednesday (April 16) within the journal Nature Astronomy.
