There was a time when the entire universe was shrouded in thick fog. Then the veil was lifted. Thanks to the stars that shone in the cores of the first galaxies, the data returned by the James Webb Space Telescope show today.
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First, there was the Big Bang. And in those early moments, our universe bore little resemblance to the universe we know today. It was filled with incredibly thick and hot gas. A gas that took hundreds of millions of years to cool. Then it was completely opaque. Then, as if ” Somebody “ Press the button “repeat”, the gas began to heat up again. ionize. Finally it became transparent.
For a long time, researchers wondered who it could be. ” Somebody “ who pressed the button “repeat”. Now, new data returned from the James Webb Space Telescope (JWST) is shedding light on this mysterious period that astronomers call the era of reionization.
to trace the offender, researchers from’Swiss Federal Institute of Technology Zurich (ETH, Switzerland) targeted a moment in the life of the universe just before the end of this reionization epoch. A moment when it wasn’t completely transparent yet, but it wasn’t completely opaque either. By pointing the JWST at a distant quasar, they got information about the gas between us and this super-bright active supermassive black hole that acts like a giant flashlight. Its light is sometimes absorbed by an opaque gas, sometimes transmitted through a transparent gas. This provided the researchers with detailed information about the composition and state of the gas in question.
An incredible quasar to illuminate
In a second step, astronomers once again relied on the James Webb Space Telescope to identify galaxies close to their line of sight. And they weren’t disappointed. Where they were hoping to find a few dozen, they finally turned up close to 120! Galaxies that were turbulent and actively forming stars. Which, for the most part, were surrounded by transparent regions with a radius of about two million light-years – roughly the distance separating our own Milky Way from the nearest galaxy, Andromeda. As if they had literally given way to the space around them at the end of the reionization era.
Thus, it appears that the first relatively small galaxies in the universe and the stars they contain were those which, by emitting quantities of light and heat, “press the repeat button” To drive reionization, release “bubbles” transparent around them. The bubbles continued to expand over the ensuing millions of years, until they merged and made our universe completely transparent. A scenario that astronomers hope to confirm soon by studying five more regions, each illuminated by a different quasar.
But in the meantime, the ETH team reports another result obtained using JWST data. Confirmation of the quasar’s massive mass allowed them to reach these conclusions. This body is not less than ten billion times the weight of our sun. This makes it the largest known black hole in the early universe. Another puzzle. Because astronomers are unable to determine the date to explain how quasars could have become so large early in our history.