Astronomers announced on Thursday (September 28) that they have captured for the first time the faint glow of the largest structure in the universe known as “The cosmic web“, a network of threads that connect galaxies across the universe. Images like these reveal valuable information about how galaxies form and evolve, and can also help track the location of the elusive dark matter that makes up about 80% of the mass of the universe. .
In 2014, astronomers Imaging the cosmic web For the first time using radiation from distant quasars, distant objects powered by black holes a billion times larger than our Sun that are believed to be the brightest objects in the universe. In 2019, other imaging efforts received help from young star-forming galaxies Illuminating the surrounding cosmic web. Now, astronomers have imaged its light directly in the darkest depths of space, between 10 billion and 12 billion light-years away.
“Before this latest discovery, we had seen filamentous structures under a lamppost,” said Christopher Martin, a professor of physics at Caltech and lead author of the new study. statement. “Now we can see them without a lamp.”
Related: Shock waves shaking the ‘cosmic web’ linking galaxies have been seen for the first time
according to Cosmic simulationmore than 60% of the hydrogen created by the great explosion About 13.8 billion years ago it collapsed to form a plate, then separated to form the network of cosmic threads we see today. These threads are connected Galaxies And feeding them with the gas necessary for growth and star formation. Although circumstantial, previous research has also suggested that galaxies form where the paths of these filaments intersect.
To capture the latest image of these intersecting filaments, Martin and his team used the Keck Cosmic Web Imager at the Keck Observatory atop Mauna Kea in Hawaii. The device was set to track emissions from hydrogen gas, the main component of the cosmic web. The 2D images produced by the instrument were later compiled to form a 3D map based on where the emissions were detected when they emerged from the cosmic web, according to the new study.
“We are essentially creating a 3D map of the cosmic web,” Martin said in the same statement. “We take spectra of every point in the image [a] A set of wavelengths, and wavelengths translate into distance.”
To detect those faint emissions, his team first had to confront a local problem: light pollution. The faint light coming from the cosmic web can easily be confused with the light filtering through the Hawaiian sky, airglow, and even the light coming from our own Milky Way Galaxy.
So the team decided to take pictures of two different spots of the sky where the cosmic web was considered at different distances. The team then took the background light from one image and subtracted it from the other, and vice versa. The result left behind only the stringy web of the web, as predicted by simulations in 2019, according to the new study, giving astronomers “an entirely new way to study the universe,” Martin said.
Scientists say images like the one taken by the new study can help them better understand how galaxies form and evolve over the ages.
This research is described in A paper It was published on Thursday (September 28) in the journal Nature.