Astronomers just found a clump of quasars which constitutes the largest structure so far observed in our universe. Astronomers named it Huge-LQG (Huge Large Quasar Group). It is elongated in shape and its largest dimension is 4 billion light-years long (meaning it would take light 4 billion years to traverse it longitudinally!) and 1.63 billion light-years across. The size of this LQG challenges the assumption of homogeneity in the cosmological principle. According to the principle of homogeneity, the same observational evidence should be available to observers at different locations in the universe, meaning that from planet Earth, what we can observe is a fair sample or a fair representation of the universe, and thus, the universe is homogeneous, no matter in which direction we look. The authors of the research paper describing the Huge-LQG say that its dimensions would indicate that there is more dark matter in some directions than in others. Not that i understand how they reached these conclusions, but I still find something of this scale mind boggling. For comparison, most galaxies are 10 million light-years across.
If you are interested, the original article, published in the Monthly Notices of the Royal Astronomical Society, can be found here.
London: Astronomers have discovered the largest known structure in the universe - a cluster of galaxies that spans an astonishing four billion light years.
It looks roach like in shape
A multinational team of astronomers led by the University of Central Lancashire has detected a large group of quasars that may be the largest known structure in the Universe.
Quasars are the nuclei of galaxies from the early days of the Universe that undergo brief periods of extremely high brightness that make them visible across huge distances. Astronomers know that quasars tend to group together in clumps of surprisingly large sizes, forming large quasar groups (LQGs).
The newly discovered structure, named the Huge-LQG, is a group of 73 quasars located in the constellation Leo. It is so large that it would take a vehicle traveling at the speed of light some 4 billion years to cross it.
According to the astronomers, the discovery also challenges the Cosmological Principle – the assumption that the Universe, when viewed at a sufficiently large scale, looks the same no matter where you are observing it from.
The modern theory of cosmology is based on the work of Albert Einstein, and depends on the assumption of the Cosmological Principle. The Principle is assumed but has never been demonstrated observationally beyond reasonable doubt.
To give some sense of scale, whole clusters of galaxies can be 2-3 Megaparsecs across, but LQGs can be 200 Megaparsecs or more across. Based on the Cosmological Principle and the modern theory of cosmology, calculations suggest that scientists should not be able to find a structure larger than 370 Megaparsecs.
The Huge-LQG however has a typical dimension of 500 Megaparsecs. But because it is elongated, its longest dimension is 1200 Megaparsecs – some 1600 times larger than the distance from the Milky Way to Andromeda.