The gravitational waves found last year were short compared with the monster waves that could be turned up by what’s called Pulsar Timing Arrays.

脉冲星计时阵列(pulsar timing array, PTA)发现的超长引力波比去年发现的引力波更长。

撰文/播音：史蒂夫·米尔斯基（Steve Mirsky）

翻译：郭鑫鹏

审校：丁可含

In 2016 the Laser Interferometer Gravitational-Wave Observatory, LIGO, made the first accepted detection of gravitational waves.

2016年，引力波激光干涉仪天文台，LIGO，第一次探测到了被认可的引力波。

“So any time you move a mass it produces a gravitational wave…so black holes, like the ones LIGO detected, these are stellar mass black holes, about 10 times the mass of the sun. When they’re in orbit they’re accelerating constantly, so constantly producing gravitational waves.”

“无论何时你移动一个有质量的东西，它会产生引力波……黑洞也是这样，就像LIGO探测到的，这些黑洞极其庞大，大约为太阳的十倍大小。当它们在轨道上运行时它们不断地加速，因此也不断辐射引力波。”

Sarah Burke Spolaor, of the National Radio Astronomy Observatory in New Mexico, at the annual meeting of the American Association for the Advancement of Science in Boston on February 18th.

位于新墨西哥州的国家射电天文台的莎拉伯克-施波拉尔，在2月18日波士顿开展的美国科学促进协会的年度会议上说。

For gravitational waves produced by the acceleration of even bigger masses, we’re going to need what’s called the Laser Interferometer Space Antenna, or LISA.

对于那些更大质量天体加速产生的引力波，我们需要被称为空间天线式激光干涉仪（the Laser Interferometer Space Antenna , LISA）。

“Now if you think of much bigger masses, something like a million times the mass of the sun, these things are moving much more slowly, much more far apart, and they’re producing lower frequency gravitational waves. And this is what LISA can detect. So LIGO, which is operating at these very fast orbits, fast frequencies, is unable to detect these things that are moving much more slowly and are on a much bigger scale.”

“现在如果你考虑更大质量物体，比如有一百万倍太阳质量的物体，这些物体移动得更慢，相互之间离得更远，它们发射低频引力波。这就是LISA能探测的。LIGO适用于快速绕行，高频，并不能检测那些更大尺寸动得更慢的物体。”

And for even bigger masses, you get to what Burke Spolaor is working on: Pulsar Timing Arrays.

对于那些更大质量物体，你需要伯克施波拉尔工作中使用的脉冲星计时阵。

“What we do with this technique is use radio telescopes to observe pulsars, which are neutron stars that are rotating very rapidly and sending their beams of emission across Earth, several hundred times per second…and the idea is of course if a gravitational wave is passing through Earth, the gravitational wave is stretching and squeezing our space time. And the tick that we see from these very, very regularly spinning pulsars is speeding up and slowing down.

“我们这个技术使用射电望远镜来观测脉冲星，那些是旋转特别快的中子星，它们的辐射波穿透地球，每秒几百次……毫无疑问，如果引力波穿过地球，它会拉伸和挤压我们的时空。而即使是最规律最稳定的脉冲星，其脉冲速度也会有上下浮动。

“Just like we can scale the stellar mass black holes that LIGO can detect, to very, very intermediate mass very large black holes that LISA can detect, Pulsar Timing Arrays will probe the very massive end of this distribution and the most massive, so the billion to even 10 billion solar mass binary black holes in the universe. So every time you get a galaxy merger you can get a binary supermassive black hole, which then will contribute signal to our Pulsar Timing Arrays by propagating through the galaxy.

“就像我们可以测量LIGO能够检测的恒星质量黑洞，一直到LISA能够检测的中等质量大黑洞，而脉冲星计时阵可以监测宇宙中最大质量分类，十亿到一百亿太阳质量黑洞双星。所以在每一次星系合并时你都能发现一对超大质量的黑洞双星，它们的信号穿过星系时便被我们的脉冲星计时阵检测到。

“Of course, gravitational waves does not stop at detection. What we really want to do is astrophysics with gravitational waves. And use it as a new tool to observe the universe and understand our place in it.”

“当然，引力波研究并不会止于检测。我们真正想做的事情是发展引力波的天体物理学。然后使用它作为观测宇宙和理解我们自身所在的新工具。”

-Steve Mirsky

https://www.scientificamerican.com/podcast/episode/how-to-find-loooong-gravitational-waves/