The brightest galaxies in our universe are fuelled by what their gravity sucks in, not through explosive mergers of star systems as scientists previously argued, researchers said Wednesday.
In what may be the most complete explanation yet of how these enormous collections of stars and dust came to be, scientists found the galaxies pulled in hydrogen gas and then used it to pump out the equivalent of up to 2,000 Suns per year, according to a study in Nature.
By comparison, our own galaxy — the Milky Way — turns out stars at the rate of about one “Sun” per year.
The brilliant light put off by these so-called submillimetre galaxies (SMGs) — named for the part of the electromagnetic spectrum they use — is all but invisible to the naked eye.
“The massive galaxy grows via [pulling in] gas from intergalactic space and forms stars at a steady but large rate for nearly a billion years,” study co-author Desika Narayanan of Haverford College in the United States told AFP.
These galaxies date from the early days of our roughly 14-billion-year-old universe, but researchers have only known about them for a couple of decades.
Their brightness, which gives off 1,000 times the light of the Milky Way, is due mostly to their prolific output of stars.
Scientists disagree on how the SMGs were born, but one of the favoured explanations is that they result from massive galaxies slamming together and exploding into an intense burst of star-making.
But Narayanan says this theory can’t account for all the qualities of super bright galaxies, especially their relatively large sizes, since mergers tend to make rather compact galaxies.
– Enigmatic galaxy –
To test their own gravity-based explanation, Narayanan and colleagues used super computers to simulate the creation of an SMG.
They found that the galaxies grew by pulling in gas that was then used to make stars which — because they were new — radiated exceptional amounts of light.
Mergers did not have a significant impact, even if SMGs can include clusters of galaxies which bump up their brightness, the study concluded.
“The galaxies collectively contribute to the local luminosity and render the system extremely bright,” Narayanan said.
The simulations were so complex that it took thousands of networked computers more than a month to do only a part of the calculations.
The team also ran models to track how light would move through these newly-created galaxies to see if the simulated outcome would resemble the real thing.
“These results provide one of the most viable models thus far for one of the most enigmatic (features of space) that we know about,” Narayanan said.
The researchers were astounded to discover that, according to their calculations, submillimetre galaxies remain super bright for almost a billion years.
Usually, intensely luminous phenomena in the universe burn out relatively quickly — a mere tens of millions of years.
Walmart pulls guns from sales floors, citing civil unrest
Walmart plans to remove guns and ammunition from its sales floors in the US following unrest in Philadelphia this week, a spokeswoman said Thursday.
The retail giant will continue to sell the items to consumers who request them, but will pull them from displays. Guns and ammunition are sold at about half of US stores, primarily in locations where hunting is popular, a company spokeswoman said.
"We have seen some isolated civil unrest and as we have done on several occasions over the last few years, we have moved our firearms and ammunition off the sales floor as a precaution for the safety of our associates and customers," a Walmart spokeswoman said. "These items do remain available for purchase by customers."
‘Signs of a coming conflict are everywhere’: Why a 2nd Civil War would be quite different from the 1st
In 2020, the United States has been rocked by everything from a deadly pandemic and a brutal recession to civil unrest in a long list of cities to fears that violent conflicts will occur either on Election Day or after the election. Journalist Matthew Gault, in an article published by Vice this week, wonders if the political divisions in the United States run so deep that the country is headed for another civil war.
Describing the unrest that has occurred this year, Gault writes, "People are marching in the streets, aligned with two ideologically distinct factions. Many of them, overwhelmingly from one side, are armed, and violence and death has resulted when these two sides have clashed. The signs of a coming conflict are everywhere."
‘#PerdueIsChicken’: Internet mocks ‘coward’ GOP senator for canceling debate after Ossoff destroyed him in viral video
Democratic Senate hopeful Jon Ossoff destroyed his Republican incumbent opponent so thoroughly Wednesday evening that Georgia Senator David Perdue has just canceled the third and final debate.
“It’s not just that you’re a crook, Senator, it’s that you’re attacking the health of the people that you represent,” Ossoff told Perdue, who had little to say in response. The viral video had been watched 5 million times by Thursday morning. It's now been viewed 9.3 million times, nearly as many times as the number of people in the entire state of Georgia.