Astronomers have found hydrogen from the early Universe

The early Universe was thought to be filled with vast reserves of hydrogen gas, but until now, astronomers have found only a handful of these essential structures.

Using data from HETDEX (Hobby–Eberly Telescope Dark Energy Experiment), a team of astronomers discovered tens of thousands of gigantic halos of hydrogen gas, which are named “nebulous Lyman-alpha“, which surrounded galaxies 10 to 12 billion years old.

Known as “cosmic noon“, this is a time in the early Universe when galaxies grew at the fastest rate.

To drive this growth, they would have needed access to vast reserves of gaseous hydrogena fundamental element for the formation of stars.

However, until recently, astronomers had found only a handful of these essential structures.

A new one, published in the magazine The Astrophysical Journalnow the number of hydrogen halos has increased by ten times: from around 3000 to more than 33,000. This confirms suspicions that These are not rare curiosities.

The study also expands the range of known sizesproviding a more representative sample for astronomers to study as they continue to unravel the origin and evolution of the first galaxies.

“We have been analyzing the same handful of objects for the last 20 years,” Erin Mentuch Cooperdata manager at HETDEX and lead author of the study. “HETDEX is allowing us to find many more of these halos and measure their shapes and sizes. It has really allowed us to create an incredible statistical catalogue.”

Hydrogen gas is notoriously difficult to detect because it does not emit light own. However, if you are close to an object that emits a lot of energy, for example, a galaxy or group of galaxies full of UV-emitting stars, that energy can make hydrogen glow.

To detect this, a lot of time needs to be spent on precision instruments, which are often in high demand.

Although previous studies have found some of these halostheir instruments could only capture the brightest and most extreme examples.

Furthermore, observations directed at early galaxies are typically so magnified that exclude all but the smallest halos. As a result, everything between the small and the giant remained undetected.

HETDEX observations are starting to fill this gap.

Using the Hobby-Eberly Telescope at the McDonald Observatory, HETDEX is map the position of more than a million galaxies in his quest to understand dark energy.

“We captured almost half a petabyte of data not only about these galaxies, but also about the regions between them,” he said. Karl GebhardtHETDEX principal investigator, chair of the astronomy department at the University of Texas at Austin and co-author of the scientific paper. “Our observations cover a region of the sky with more than 2000 Full Moons. The scope is enormous and unprecedented.”

“The Hobby-Eberly Telescope is one of the largest in the world”, notes Dustin DavisUT Austin researcher, HETDEX scientist and study co-author. “And the instrument used by HETDEX produces 100,000 spectra in each observation. So we have enormous amounts of data and there are all kinds of interesting, fun and strange things waiting to be discovered.”

The newly revealed halos measure from tens to hundreds of thousands of light years in diameter. Some are as simple as a football-shaped cloud surrounding a single galaxy. Others are irregular, sprawling patches that contain multiple galaxies. “These are the most fun“, said Mentuch Cooper. “They look like giant amoebas with tentacles stretching through space.”

To find them, the team selected the 70,000 brighter of the more than 1.6 million early galaxies that have been identified by HETDEX so far.

With the help of supercomputers from TACC (Texas Advanced Computing Center), they sought to see how many showed signs of a surrounding halo: a compact central region of hydrogen and a thinner cloud that extends beyond it.

Almost half had. Furthermore, this fraction is likely an underestimate, explained Mentuch Cooper. “We suspect that the faintest systems are simply not bright enough to fully reveal their size.”

The team hopes their discovery will help others study the early Universe: how their structures evolved, the distribution of matterthe movement of objects and much more. With 33,000 halos to study, the problem will no longer be where to find them, but rather which one to choose.

“There are several models for galaxies at this time that largely work and seem to make sense, but there are gaps and flaws,” Davis explained. “Now we can focus on individual halos and see in greater detail the physics and mechanics of what is happening. And then we can correct or discard the models and try again.”