科學家發(fā)現(xiàn)了沒有任何暗物質(zhì)的神秘星系

科學家發(fā)現(xiàn)了沒有任何暗物質(zhì)的神秘星系

True to its name, dark matter has long been one of the universe's biggest mysteries. It is, after all, invisible, emitting no light whatsoever. And yet, we know it exists by the gravitational strings it pulls. Stars, literally, dance to the beat of dark matter.

正如其名，暗物質(zhì)一直是宇宙中最大的謎團之一。畢竟，它是看不見的，不發(fā)出任何光。然而，我們知道它是通過它所拉動的引力弦而存在的。毫不夸張地說，恒星會隨著暗物質(zhì)的節(jié)奏起舞。

We have never seen a speck of it, but scientists say the universe is oozing with dark matter. (Photo: pixelparticle/Shutterstock)

"Motions of the stars tell you how much matter there is," Yale University researcher Pieter van Dokkum noted in 2016. "They don't care what form the matter is, they just tell you that it's there."

2016年，耶魯大學研究員Pieter van Dokkum指出:“恒星的運動告訴你有多少物質(zhì)。”“他們不關(guān)心物質(zhì)的形式，他們只告訴你物質(zhì)就在那里。”

At the time, van Dokkum was hailing the discovery of a galaxy with unusually high levels of dark matter — a place that boasts 99.99 percent of the stuff. On average, dark matter is estimated to make up around 27 percent of the universe.

當時，范多克姆正在為發(fā)現(xiàn)一個暗物質(zhì)含量異常高的星系而歡呼——這個星系擁有99.99%的暗物質(zhì)。據(jù)估計，暗物質(zhì)平均占宇宙的27%左右。

But now researchers have made a discovery that could shatter our existing theory about how the universe is formed: No less than 19 galaxies seem to be missing dark matter altogether. Instead, dark matter's nemeses, called baryons, seem to dominate these dwarf galaxies.

但現(xiàn)在研究人員有了一項發(fā)現(xiàn)，可能會顛覆我們現(xiàn)有的關(guān)于宇宙形成的理論:至少有19個星系似乎完全沒有暗物質(zhì)。相反，暗物質(zhì)的對手——重子——似乎主宰著這些矮星系。

Baryonic matter, comprising protons and neutrons, is the stuff we're more accustomed to — the matter scientists can relatively easily detect and measure. These newly discovered galaxies may be entirely composed of ordinary, run-of-the-mill baryonic matter.

重子物質(zhì)，包括質(zhì)子和中子，是我們更熟悉的物質(zhì)——科學家可以相對容易地探測和測量這些物質(zhì)。這些新發(fā)現(xiàn)的星系可能完全由普通的，運行的重子物質(zhì)組成。

Dark matter is typically detected by the influence of its gravity on stars. (Photo: Vladimir Arndt/Shutterstock)

In the research paper, published in the journal Nature Astronomy, measured the swirl of 19 galaxies. That swirl factor tells scientists how much dark matter a galaxy contains. More specifically, they looked at the H1 rotation factor in these galaxies. That's the motion of hydrogen atoms as they're being swished around under dark matter's inexorable influence.

發(fā)表在《自然天文學》雜志上的研究論文測量了19個星系的旋渦。旋流因子告訴科學家星系中有多少暗物質(zhì)。更具體地說，他們研究了這些星系中H1旋轉(zhuǎn)因子。這是氫原子在暗物質(zhì)不可阻擋的影響下被甩來甩去的運動。

And to their surprise, they found those hydrogen atoms were completely free from dark matter's sway. How is it possible that an ingredient so essential in the formation of galaxies could be missing? (Dark matter pulls atoms of gas together to form stars.)

令他們驚訝的是，他們發(fā)現(xiàn)這些氫原子完全不受暗物質(zhì)的影響。星系形成中如此重要的成分怎么可能消失呢?(暗物質(zhì)將氣體原子聚集在一起形成恒星。)

Well, if their findings prove accurate, prevailing theories on how galaxies are formed from the interplay of dark and baryonic matter would need a complete reset.

好吧，如果他們的發(fā)現(xiàn)被證明是正確的，那么關(guān)于星系是如何由暗物質(zhì)和重子物質(zhì)相互作用而形成的流行理論將需要一個徹底的重置。

And it wouldn't be the first time scientists noted a galaxy seemingly bereft of dark matter. Last year, Yale researchers detected a similar phenomenon in a faraway galaxy known as NGC 1052–DF2.

這也不是科學家們第一次發(fā)現(xiàn)一個星系似乎沒有暗物質(zhì)。去年，耶魯大學的研究人員在一個名為NGC 1052-DF2的遙遠星系中發(fā)現(xiàn)了類似的現(xiàn)象。

What does it all mean for astrophysicists? There are still plenty of variables that may have thrown off their findings. For one thing, measuring the H1 rotation of a distant galaxy is easily skewed if its angle from Earth isn't calculated just right.

這對天體物理學家來說意味著什么?他們的研究結(jié)果仍然有很多變數(shù)。首先，測量一個遙遠星系的H1旋轉(zhuǎn)很容易發(fā)生偏斜，如果它與地球的角度計算不正確的話。

Another wildcard could be the presence of a supernova, which can have a profound effect on a galaxy's rotation. But if their findings are confirmed, then that ever-elusive material known as dark matter may have once again thrown science for a loop — and forced us to rethink how the universe came to be in the first place.

另一個未知因素可能是超新星的存在，它會對星系的旋轉(zhuǎn)產(chǎn)生深遠的影響。但如果他們的發(fā)現(xiàn)得到證實，那么被稱為暗物質(zhì)的難以捉摸的物質(zhì)可能會再次把科學拋入一個循環(huán)——并迫使我們重新思考宇宙最初是如何形成的。