数以百万计的高速黑洞，可能正在绕银河系旋转

数以百万计的高速黑洞，可能正在绕银河系旋转

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.

黑洞是如何诞生的?天体物理学家有理论，但我们并不确定。它可能是大质量恒星悄无声息地爆发出一个floompf，也可能是黑洞在巨大的超新星爆炸中诞生。现在，新的观察结果表明，可能确实是后者。

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).

事实上，研究表明这些爆炸是如此强大，它们能以超过每秒70公里(43英里/秒)的速度将黑洞踢过星系。

"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.

“这项工作基本上谈论第一个观测证据,你可以看到在星系中黑洞高移动速度,并将它踢黑洞系统收到出生时,“科廷大学和国际射电天文学研究中心的天文学家派基·阿特里在接受Science Alert采访时表示。

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.

这意味着可能有数以百万计的恒星质量黑洞以高速围绕着银河系旋转。这篇论文目前已预先印刷，已被英国皇家天文学会的月报所接收。

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.

这项研究基于16个双星系统中的黑洞。除非它们主动进食，否则我们实际上无法找到黑洞，因为任何可探测到的电磁辐射都无法逃脱它们疯狂的引力。但如果它们是一对双星，并且活跃地以另一颗恒星为食，围绕黑洞旋转的物质就会发出强大的x射线和无线电波。

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.

一旦我们能看到这些黑洞信标，我们就能看到黑洞的行为。国际研究小组利用这种行为试图重建黑洞的历史。

"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.

阿特里解释说：“我们追踪了这些星系在银河系中的运动情况，计算出它们今天的速度，回到过去，并试图了解星系诞生时的速度，这16个星系中的每一个都有各自的速度。”

"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."

“根据这些速度，你实际上可以知道它们是在超新星爆炸中诞生的，还是在没有超新星爆炸的情况下直接坍缩的。”

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.

我们知道，中子星可以被它们自己的超新星爆炸以高速猛烈地冲出太空，这被称为布拉奥(blaauw)一脚，或称为纳塔尔(natal)一脚，这种情况发生在超新星爆炸不平衡时，产生后坐力。

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.

目前还不清楚黑洞是否也能以同样的方式被踢出去。假设，它们可能——实际上，7个黑洞x射线双星之前就与出生踢有关。

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.

这项新研究对这些以及其他9个系统进行了更详细的分析，结合了测量到的适当运动、系统径向速度和到这些系统的距离，进行了迄今为止最详细的分析。

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.

研究人员发现，在这16个黑洞x射线双星中，有12个确实具有高速和轨迹，这表明了一种先天的撞击。这是样本的75%如果这个数字扩大到银河系中估计有1000万个黑洞，这可能意味着大约有750万个高速黑洞在那里倾斜。1000万是一个较低的估计。

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.

与之前的理论一致，这些加速的黑洞比被踢出的中子星慢三到四倍，这是因为它们的质量更高。有趣的是，黑洞的质量和速度之间似乎没有关联，这意味着我们还不知道恒星的质量和超新星爆发的可能性之间是否有关联。

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.

当然，这只是相对较小的黑洞样本。但是，根据阿特里的说法，这是朝着建立一个更大的样本迈出的一步，这个样本可以帮助我们理解恒星是如何进化和死亡的，以及黑洞是如何产生的。

"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.

她补充说:“最终，所有这些都将进入我们所期望的银河系中有多少黑洞，有多少黑洞会合并，从而实现LIGO所发现的引力波探测。”

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.

了继续这项研究，研究小组将继续观察天空。这些双星系统并不总是明亮的——它们来来去去，转瞬即逝。因此，研究人员希望能找到更多这样的双星系统来继续进行银河系黑洞的普查，无论是否加速。

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，如果你现在担心一个黑洞正在进入我们的太阳系，你不需要惊慌。

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

阿特里说：“最近的黑洞，离我们有6523光年远。”

"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、非常遥远。所以我们不可能很快被任何黑洞吞没。”