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Mapping the Universe through Quasars
An extensive map of the universe was constructed through the positions of nearly 1.3 million quasars, with some of them existing just 1.5 billion years after the Big Bang. By comparing this newly formed map with the cosmic microwave background (CMB), scientists have been able to approximately confirm the distribution and density of matter in the universe. This comparison offers valuable insights into how large-scale structures in the universe have evolved over cosmic history.
The map, named “Quaia,” is derived from a catalog of 1,295,502 quasars positions and redshifts and is a blend of “quasar” and “Gaia,” referencing the European Space Agency’s Gaia astrometric space mission. The primary goal of Gaia is to map the positions and motions of up to a billion stars within our Milky Way galaxy. However, the mission has also observed millions of background galaxies and quasars in the process.
Quasars as Cosmological Guides
Quasars serve as remarkable guides in drawing cosmological maps. These cosmic entities represent the core of active galaxies where supermassive black holes voraciously consume vast amounts of matter. While light cannot escape the black hole itself, the accretion disk formed by infalling matter spirals around the black hole, reaching extreme densities and temperatures, emitting powerful jets of charged particles. The remarkable luminosity of a quasar makes them easily visible even at significant cosmological distances, serving as useful tools in cosmological research.
Moreover, quasars are typically situated within the densest clusters of dark matter in the universe. This phenomenon corresponds to the gravitational pull of the surrounding dark matter halo, directing materials towards the quasar to fuel the black hole. Mapping these profoundly bright celestial bodies enables scientists to also unveil the enigmatic nature of invisible dark matter scattered throughout the universe.
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