After the Big Bang came the Dark Ages, a period lasting hundreds of millions of years when the universe was largely without light. It ended in the epoch of reionization when neutral hydrogen atoms became charged for the first time and the first generation of stars started to form. The question that has perplexed astronomers is what caused the first hydrogen atoms to charge. A team of researchers have observed an early quasar that pumped out enormous amounts of x-ray radiation helping to drive the reionization. 

The universe began with the Big Bang around 13.8 billion years ago, starting as a hot, dense point that was infinitely small. In the first few minutes, light elements like hydrogen and helium formed, and a few hundred million years later – possibly as early as 380,000 years, the Cosmic Microwave Background (CMB) marked the end of the Dark Ages. Gravity then pulled matter together, forming the first stars and galaxies during the Epoch of Reionization. These early stars ionized hydrogen, making the universe transparent. Over billions of years, galaxies merged and structures formed, with our solar system emerging around 4.6 billion years ago. 

The transition between the Dark Age and the Reionization phase has been the subject of study by a team of astronomers from Yale University. They have detected intense periods of brightening and dimming of a quasar about 12 billion light years away. The observation sheds some light on the accelerated rate of growth experienced by some objects in the early universe.

The quasar identified by the team goes by the catchy title J1429+5447. It’s found in the constellation of Lyra and is so far away that its light takes 12 billion years to reach us, this means we see it now as it was just 1.6 billion years after the Big Bang. Studying it gives us a real insight into the early evolution of the universe. At its centre is a supermassive black hole which accretes matter and in the process emits intense amounts of radiation across the whole electromagnetic spectrum. The team announced their discovery on 14 January at a meeting of the American Astronomical Society. 

Using NuSTAR, an X-ray space telescope to study the quasar they compared their observations with previous studies 4 months earlier using the Chandra X-ray telescope. To their surprise, in just 4 months, the X-ray emissions from the quasar doubled! 

Meg Urry, Professor of Physics and Astronomy and co-author explained ‘The level fo X-ray variability in terms of intensity and rapidity is extreme.  It is almost certainly explained by a jet pointing toward — a cone in which particles are transported up to a million light years away from the central, supermassive black hole. Because the jet moves at nearly the speed of light, effects of Einstein’s theory of special relativity speed up and amplify the variability.”

The team believe these early quasars like J1429+5447 provided the energy to end the Dark Ages and herald in the Reionisation period. Their study has revealed how crucial quasars were to the early evolution of the universe.

Source : This quasar may have helped turn the lights on for the universe