Halo Around Milky Way Is Far Hotter Than Astronomers Thought

(CN) — Researchers have determined that the dark and mysterious halo that encircles the Milky Way is far hotter — potentially by a factor of 10 — than previous estimates suggested.

Of the countless features of our galaxy, one of the most fascinating that researchers have long puzzled over is the massive and dusty halo that wraps around the entire Milky Way.

While numerous facts surrounding the halo continue to elude astronomers, researchers believe that it contains the largest amount of mass in the entire galaxy and houses some of the Milky Way’s most ancient stars.

Researchers also say that this hazy and foggy halo contains notable amount of dark matter, a special variety of matter that does not reflect or emit light. It is theorized that dark matter may make up the vast majority of all matter in the universe, with many researchers suggesting that some of the greatest cosmic secrets scientists have yet to uncover may be learned through a deeper understand of dark matter itself.

While countless questions continue to dog researchers over the Milky Way’s halo and what rests inside, scientists report that they may have found a new piece to the puzzle.

During this week’s annual meeting of the American Astronomical Society, held online due to the ongoing Covid-19 crisis, astronomers at Ohio State University revealed that the massive halo around our galaxy may be much hotter than was previously believed — potentially by up to at least 10 times the previous estimates.

This new estimate, researchers say, would put the halo’s temperature at around 18 million degrees Fahrenheit.

Scientists point out that this massive increase in temperature was already previously reported in a previous research study, but that such findings were specific to include only certain areas of the galaxy’s halo. This new research, however, suggests that those massive temperatures could be found throughout the entire halo.

Smita Mathur, professor of astronomy at Ohio State and senior researcher on the studies presented, said that while these findings are not definitive yet, the possibilities are no less exciting.

“We can’t say for sure that it is everywhere, because we have not analyzed the entire halo,” Mathur said with the release of the study. “But we know now that the temperatures we saw in the first study definitely are not unique, and that is very exciting.”

Astronomers made these series of findings through studying data taken from the XMM-Newton telescope, an X-ray observatory telescope operated by the European Space Agency. This telescope is specifically able to extract data on this issue given that it operates on an X-ray spectrum and can pick up information that would otherwise be blocked by the Earth’s atmosphere.

Data from this telescope offered the first suggestion that Milky Way’s halo was so exceptionally warm.

This telescope only points in a single direction however, forcing scientists to wonder if the results they were seeing were unique to just that one direction.

“It showed us that the halo was much hotter than we had known, but it didn’t show us whether that was the case throughout the galaxy, or if the telescope had picked up an aberration caused by an unknown force coming from the direction where the telescope was pointed,” Mathur said.

This led scientists to widen their search. Anjali Gupta, an astronomy researcher visiting Ohio State, went on to analyze data taken from a different telescope known as Suzaku. This Japanese telescope also operates on an X-ray spectrum, but unlike the first telescope, it collected data on the halo from four different directions.

A breakdown of this data revealed that not only were the original findings on the increased temperatures of the halo correct, but that such temperatures are likely to be consistent across the entire halo.

These results help astronomers attain a better understanding of a cosmic feature they could be crucial to understanding galaxies.

Given that these halos serve as the final bridge between a galaxy and the greater universe beyond, not to mention that unique properties and amounts of dark matter they possess, researchers say that the learning more about these halos could help us better understand how galaxies have formed and changed throughout the universe’s lifetime.

“We are trying to learn about the elements that form these halos, and about the temperatures there,” Mathur said. “Knowing those things can help us understand more about how galaxies connect with the rest of the universe, and how they formed and where elements might have come from.”

Further adding to the intrigue is the fact that our galaxy is not the only one with a mysterious halo. A previous study analyzed data from a galaxy some 200 million light years away, one that bears a striking resemblance to the Milky Way. Data suggests that the distant galaxy also wears a massive halo around it, and that its halo is just as shockingly hot as ours.

Astronomers are hopeful these newly discovered connections and crucial commonalities could hold the key to a far richer understanding of our universe and the greater cosmos itself.

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