Venturing deep into the Great Attractor
Embedded Files
By Jyotiraditya Chatterjee, BS-MS 2020
The Great attractor seems to be a gravitational anomaly and an apparent central point of the Leniakea Supercluster. The anomaly is observable by its gravitational influence and the effect on motions of many galaxies and their associate clusters over hundreds and millions of light-years across the universe, showing that there might be a mass that is several million billion times the mass of our sun! We will look into what might be lying up there or we might even find something which we didn’t expect at all.
So the astronomers have long known that the Milky Way is moving toward the constellation Centaurus at a speed of 1.4 million mph, but the reason for the movement remained a topic of debate. Over 20 years ago, it was suggested that the motion was due to the gravitational pull of a nearby large concentration of matter dubbed the Great Attractor. The Great Attractor is what is known as a supercluster, that is, a group of clusters of galaxies, and was estimated to contain matter equal to more than 10 million billion times the mass of the sun!
Until now, efforts to find the Great Attractor were hampered by its location in the "zone of avoidance", an area behind the plane of the Milky Way where gas and dust within our galaxy block much of the visible light from objects outside it. The new survey, Clusters in the Zone of Avoidance (CIZA), is the first to search for the X-ray signatures of galaxy clusters behind the Milky Way and investigate the nature of the Great Attractor. Due to the difficulty of observing through the Milky Way, this region was the final portion of the sky in which the cluster population had yet to be mapped.
Since X-rays can penetrate even regions that are extremely obscured by gas and dust, and galaxy clusters are sources of X-rays. This is what prompted the scientists to attempt to map the distribution of galaxy clusters behind the plane of the Milky Way using X-ray observations.
During their study, Kocevski and collaborators report finding far fewer massive cluster systems near the Great Attractor than would be expected given the region's proposed mass. One of their goals was to uncover the true mass of the Great Attractor, but what they found was that it is not that “great” after all...
Instead, the CIZA team identified a significant concentration of galaxies behind the Great Attractor, near the Shapley Supercluster! which lies 500 million light-years away or four times the distance to the Great Attractor region. It contains the equivalent of nearly 10,000 Milky Ways or four times the amount of mass currently observed in the Great Attractor region itself!! This means that the astronomers found something even more massive than the Great attractor!!
Two-dimensional projection of the cluster population within 800 million light-years of the Milky Way.
After the mapping of the galaxy cluster population over the entire sky for the first time, scientists found that how all the clusters surrounding the Milky Way were being affected and found that only 44% of our galaxy's motion through space is due to the gravitational pull of galaxies in the nearby Great Attractor region… The remaining portion is the result of a large-scale flow in which much of the local Universe, including perhaps the Great Attractor itself, is being pulled towards the Shapley Supercluster!!
This means that the Milky Way's motion was influenced by Even more massive structures which were more distant than the Great Attractor! and this study was the first to reach this conclusion after having fully mapped the Great Attractor and regions behind it.
The finding resolves one of the long-standing problems associated with the Great Attractor. The presence of a massive overdensity relatively close to the Milky Way suggested that extreme mass concentrations such as the Great Attractor were fairly common in the Universe. This implied that the Universe contained much more matter than was measured by other means such as supernova Ia observations. The finding of a less massive Great Attractor and the large distance to the Shapley supercluster implies that extremely massive overdensities are rare in the Universe.
But this study just makes things more interesting for future studies in the field of astronomy, as we still need to find a better mapping of more of those extreme superclusters lying in the beyond, far away in the shadows of the cosmos…
For more information into the recent studies check out these research articles (link given below):
Page updated
Google Sites
Report abuse