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中子星合并引力波和伽马射线 – 译学馆
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中子星合并引力波和伽马射线

Neutron Star Merger Gravitational Waves and Gamma Rays

由于对引力波测量的
Due to the crazy technological challenges that had to be overcome
惊人技术突破
in order to detect gravitational waves,
有些人怀疑科学家有没有真的完成了这些突破
some people were skeptical that scientists had actually done it,
他们有没有真的从黑洞观察到引力波
that they’d actually seen gravitational waves from black holes
毕竟没有确证
after all, there was no corroboration
但在今天宣布的这次发现以后
But,after the discovery that’s being announced today,
就没有质疑声了
there can be no more doubt
因为科学家观察到了一千三百万年外
because scientists have detected the merging of two neutron stars
两个合并的中子星
a hundred and thirty million light years away.
这是第一次
This is the first ever detection of gravitational waves from in-spiraling neutron stars,
从内旋中子星观察到引力波
from in-spiraling neutron stars,
激动人心的是
and what’s really exciting about this detection is that
相同的活动也被电镜
the same event has been observed with telescopes
在所有电磁光谱范围检测到
in all areas of the electromagnetic spectrum.
故事从八月17日东部时间8:41开始
It all began on August 17th at 8:41 a.m.
当时LIGO检测到
Eastern Time when LIGO interferometers identified a clear
一个清晰的持续约100秒的引力波
a clear gravitational wave signal that lasted about a hundred seconds,
这比先前所有的观测
which is way longer than any previous detection
都要长得多
and it’s consistent with theoretical predictions for the signal
而且与理论对两个合并中子星的信号的预测一致
from two merging neutron stars. [“hear” the sound of two stars colliding ♪]
大约1.7秒之后 NASA的费米gamma线电子望远镜确定了一个gamma射线爆发
Around 1.7seconds later NASA’s Fermi gamma-ray telescope identified a burst of gamma rays.
几十年以来 伽马射线暴
For decades gamma-ray bursts have been thought to
被认为是来自中子星合并
come from neutron star mergers,
但缺乏证据
but the evidence has been lacking
要确认这些引力波和伽马射线发射
to know for sure that these gravitational waves and the gamma ray burst
来自于同一事件
came from the same event.
关键在于确定中子星合并的位置
The key was to locate where in the sky this neutron star merger occurred.
不同于黑洞合并
Unlike a merger of black holes neutron stars
中子星合并时发出光
emit light when they smash together and continue emitting electromagnetic radiation afterwards
并随后持续发射电磁辐射 费米伽马空间电子望远镜
The Fermi gamma-ray Space Telescope
观测一大片太空
identified a large patch of the sky
大约6000个满月大小
roughly the size of six thousand full moons.
用欧洲太空总署INTEGRAL卫星
Using the European Space Agency’s integral gamma-ray satellite,
可以缩小范围
they were able to narrow down that range.
现在被LIGO探测到的引力波
Now,the gravitational waves detected
可以用来检测空中两个长条区域
by LIGO allowed them to identify two long strips in the sky,
其中一个于现有研究范围有重叠
one of which overlapped with the existing search area
有趣的是 Virgo 它是最新的引力波检测器
Now,interestingly,Virgo,which is the newest gravitational wave detector
在意大利,那时开机
which is in Italy,it was online at the time,
应该可以很轻松的
and it should have easily
探测到这些引力波
been able to detect these gravitational waves
但是却什么都没观测到
and yet,it saw almost nothing,
那就是证据
and that was kind of a key clue
因为它表明引力波必须来自
because it indicated that the gravitational waves must be coming from
检测器的一个盲点
one of that detector’s blind spots.
每个干涉测量器都有一些盲点
Every interferometer has some blind spots
如果波从那个角度传来
but if the waves are coming at that angle
对于两臂对称的话 就无法被检测到
it’s symmetricwith respect to the two arms and so it just can’t be detected.
这样就进一步将搜索范围
So this helped further narrow the search area
缩小至大约
down to the size of about
144个满月大小
144 full moons
在那个范围里
Now,within that area,
约50个星系被确认和用光学望远镜研究
around fifty galaxies were identified to be studied with optical telescopes
仅仅在初次观测的11小时后
and just 11 hours after the initial detection astronomers
天文学家定位了
located a bright spot in the galaxy NGC 4993.
一个位于NGC4993的亮点
You are seeing here pictures of the light
这里展示的是一亿三千万年前
from two neutron stars that merged
两个中子星合并发出的光
130 million years ago.
请看碰撞之后光的颜色和亮度是怎么变化的
Watch how the color and brightness changes in the aftermath of the collision.
中子星是什么
So what are neutron stars?
它们是大恒星爆炸后
Well,they’re the leftover cores of big stars that have exploded –
留下的超新星的残余核
they’ve gone supernova
这些残余核被引力压缩
Now,those remaining cores are squeezed down by gravity
如果太大
and if they’re too big,
比如说大于两三个太阳质量
say larger than two or three solar masses
它们会不断坍缩
well,they will keep on getting crushed until they collapse
直到变成黑洞
until they collapse in on themselves forever and become a black hole.
如果那些核小一些
But if those cores are a little smaller
比如1.1或1.6个太阳质量
say 1.1 and 1.6 times the mass of our Sun,
它们还是被挤压
as they were in this case
导致电子和质子碰撞
well,then they get squeezed still
而形成中子和中微子
and so electrons merge with protons to form neutrons
中微子发射
and neutrinos and the neutrinos take off
中子会留在
and the neutrons are left
一个十分紧密的星体内
in a really really densely packed star.
中子不会互相结合的原因
And the only reason the neutrons don’t
是泡利发现的
don’t ‘combine with each other is because of a quantum principle,
泡利不相容原理
the Pauli exclusion principle
简单来说你不能
that basically says you can’t put two of these particles
将这些粒子互相叠加
right on top of each other,
而实际上那是中子星存在的原因
and that’s actually the only thing holding that neutron star up
如果有两个中子星
So if you have two of these neutron stars
互相旋转
of these neutron stars and they are orbiting each other, well,
它们就会以引力波的形式释放一些能量
then they emit some of their energy as gravitational waves,
与此同时
and as they do that
它们因为消耗能量而越来越近
they lose energy, meaning they spiral
当它们足够靠近
in closer to each other and when they get really close
到只有几百公里的时候
you’ll see a few hundred kilometers apart,
引力波开始变强
the gravitational waves become intense,
让我们能在几亿光年意外也能探测到
allowing us to detect them hundreds of millions of light years away.
中子星碰撞释放残骸到太空中
The collision of neutron stars creates a kilonova which spews debris out into space.
这些残骸发出光
This is debris that glows,
可以让我们观察什么被创造出来了
allowing us to observe what’s been created
实际上有了新的证据
and in fact, the new observations with light telescopes
表明重元素如金、铂、铅
have shown that heavy elements
是在这一过程中产生的
like gold,lead and platinum were made in this event, and that
也让我们明白我们宇宙的重元素
and that helps us understand where a lot of the heavy elements
从哪里来
in our universe come from.
在我看来 这一事件向我们展示
In my view, this event really shows us
我们正处在天文学的一个新时代
that we’re ‘in a new age of astronomy.
我们不仅可以从黑洞
We can detect gravitational waves, not just from black holes,
也可以从中子星探测引力波
but now from neutron stars,
我们可以用这一信息去定位
we can use that information to locate places
引力波的产生位置
in the sky where that occurred and we can validate
我们还可以用其他电子望远镜观测所有电磁波谱
that with our other telescopes looking in all parts of the electromagnetic spectrum
现在我们有更多的工具去理解我们的宇宙
So,now we really have more tools to understand our universe
我已经等不及想知道
and I just can’t wait for the questions
我们下一个能解释的问题了
that we’re going to address next and all of the different things
以及引力波天文观测台的不断优化
we’re going to be able to study as the gravitational wave
带给我们更多的研究可能
observatories get better and better.
现在是研究宇宙的伟大时代
It’s a phenomenal time to be studying the universe.
【末尾音乐】
[Outro signal]

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