數以百萬計的高速黑洞，可能正在繞銀河系旋轉

數以百萬計的高速黑洞，可能正在繞銀河系旋轉

How are black holes born? Astrophysicists have theories, but we don't actually know for certain. It could be massive stars quietly imploding with a floompf, or perhaps black holes are born in the explosions of colossal supernovas. New observations now indicate it might indeed be the latter.

黑洞是如何誕生的?天體物理學家有理論，但我們并不確定。它可能是大質量恒星悄無聲息地爆發(fā)出一個floompf，也可能是黑洞在巨大的超新星爆炸中誕生?，F在，新的觀察結果表明，可能確實是后者。

In fact, the research suggests that those explosions are so powerful, they can kick the black holes across the galaxy at speeds greater than 70 kilometres per second (43 miles per second).

事實上，研究表明這些爆炸是如此強大，它們能以超過每秒70公里(43英里/秒)的速度將黑洞踢過星系。

"This work basically talks about the first observational evidence that you can actually see black holes moving with high velocities in the galaxy and associate it to the kick the black hole system received at birth," astronomer Pikky Atri of Curtin University and the International Centre for Radio Astronomy Research (ICRAR) told ScienceAlert.

“這項工作基本上談論第一個觀測證據,你可以看到在星系中黑洞高移動速度,并將它踢黑洞系統(tǒng)收到出生時,“科廷大學和國際射電天文學研究中心的天文學家派基·阿特里在接受Science Alert采訪時表示。

And it means there are potentially millions stellar-mass black holes zooming around the galaxy at high speed. The paper, currently available in pre-print, has been accepted into the Monthly Notices of the Royal Astronomical Society.

這意味著可能有數以百萬計的恒星質量黑洞以高速圍繞著銀河系旋轉。這篇論文目前已預先印刷，已被英國皇家天文學會的月報所接收。

The study was based on 16 black holes in binary systems. Unless they're actively feeding, we can't actually find black holes, since no detectable electromagnetic radiation can escape their insane gravity. But if they're in a binary pair and actively feeding on the other star, the matter swirling around the black hole gives off powerful X-rays and radio waves.

這項研究基于16個雙星系統(tǒng)中的黑洞。除非它們主動進食，否則我們實際上無法找到黑洞，因為任何可探測到的電磁輻射都無法逃脫它們瘋狂的引力。但如果它們是一對雙星，并且活躍地以另一顆恒星為食，圍繞黑洞旋轉的物質就會發(fā)出強大的x射線和無線電波。

Once we can see these black hole beacons, we can see how the black hole is behaving. The international team of researchers used this behaviour to try and reconstruct the black hole's history.

一旦我們能看到這些黑洞信標，我們就能看到黑洞的行為。國際研究小組利用這種行為試圖重建黑洞的歷史。

"We tracked how these systems were moving in our galaxy - so, figured out their velocities today, moved back in time, and tried to understand what the velocity was of the system when it was born, individually for each of these 16 systems," Atri explained.

阿特里解釋說：“我們追蹤了這些星系在銀河系中的運動情況，計算出它們今天的速度，回到過去，并試圖了解星系誕生時的速度，這16個星系中的每一個都有各自的速度。”

"Based on the velocities, you can actually find out if they were born with a supernova explosion, or if the stars just directly collapsed onto themselves without a supernova explosion."

“根據這些速度，你實際上可以知道它們是在超新星爆炸中誕生的，還是在沒有超新星爆炸的情況下直接坍縮的。”

We know that neutron stars can be violently punted out across space at high speeds by their own supernova explosions - this is called a Blaauw kick, or natal kick, and it happens when the supernova explosion is lopsided, resulting in a recoil.

我們知道，中子星可以被它們自己的超新星爆炸以高速猛烈地沖出太空，這被稱為布拉奧(blaauw)一腳，或稱為納塔爾(natal)一腳，這種情況發(fā)生在超新星爆炸不平衡時，產生后坐力。

It was unknown if black holes could be kicked in the same way. Hypothetically, they might - and indeed seven black hole x-ray binaries have been previously associated with natal kicks.

目前還不清楚黑洞是否也能以同樣的方式被踢出去。假設，它們可能——實際上，7個黑洞x射線雙星之前就與出生踢有關。

The new research has analysed these, as well as nine others, in greater detail, combining measured proper motions, systemic radial velocities, and distances to these systems for the most detailed analysis yet.

這項新研究對這些以及其他9個系統(tǒng)進行了更詳細的分析，結合了測量到的適當運動、系統(tǒng)徑向速度和到這些系統(tǒng)的距離，進行了迄今為止最詳細的分析。

The researchers found that 12 of these 16 black hole X-ray binaries did indeed have high velocities and trajectories that indicated a natal kick. That's 75 percent of the sample. If this scales up to the estimated 10 million black holes in the Milky Way, that might mean around 7.5 million high-speed black holes careening out there. And 10 million is a low estimate.

研究人員發(fā)現，在這16個黑洞x射線雙星中，有12個確實具有高速和軌跡，這表明了一種先天的撞擊。這是樣本的75%如果這個數字擴大到銀河系中估計有1000萬個黑洞，這可能意味著大約有750萬個高速黑洞在那里傾斜。1000萬是一個較低的估計。

In line with previous theories, these speeding black holes are slower than kicked neutron stars by a factor of about three or four, due to their higher mass. Interestingly, there seemed to be no correlation between black hole mass and velocity, which means we don't yet know if there's a correlation between progenitor star mass and the likelihood of a supernova.

與之前的理論一致，這些加速的黑洞比被踢出的中子星慢三到四倍，這是因為它們的質量更高。有趣的是，黑洞的質量和速度之間似乎沒有關聯(lián)，這意味著我們還不知道恒星的質量和超新星爆發(fā)的可能性之間是否有關聯(lián)。

This is a relatively small sample size of black holes, of course. But, according to Atri, it's a step towards building up a larger sample that can help us to understand how stars evolve and die, and give rise to black holes.

當然，這只是相對較小的黑洞樣本。但是，根據阿特里的說法，這是朝著建立一個更大的樣本邁出的一步，這個樣本可以幫助我們理解恒星是如何進化和死亡的，以及黑洞是如何產生的。

"Eventually, all of this will feed into how many black holes we expect in our galaxy, how many black holes that will actually merge to give those gravitational wave detections that LIGO finds," she added.

她補充說:“最終，所有這些都將進入我們所期望的銀河系中有多少黑洞，有多少黑洞會合并，從而實現LIGO所發(fā)現的引力波探測。”

To continue to build on the research, the team will keep watching the sky. These binary systems aren't always bright - they come and go, transient. So the researchers are hoping to find more of these binary systems to continue building a census of Milky Way black holes, whether speeding or not.

了繼續(xù)這項研究，研究小組將繼續(xù)觀察天空。這些雙星系統(tǒng)并不總是明亮的——它們來來去去，轉瞬即逝。因此，研究人員希望能找到更多這樣的雙星系統(tǒng)來繼續(xù)進行銀河系黑洞的普查，無論是否加速。

And, in case you're worried right now about a black hole cruising right into our Solar System, you don't really need to panic.

而且，如果你現在擔心一個黑洞正在進入我們的太陽系，你不需要驚慌。

"The closest black hole, we think it's two kiloparsecs away [6,523 light-years]," Atri said.

阿特里說：“最近的黑洞，離我們有6523光年遠。”

"It's very, very far away. So there's no chance that we're getting sucked up by any black hole any time soon."

“它非常、非常遙遠。所以我們不可能很快被任何黑洞吞沒。”