天文学家发现星系中有3个超大质量黑洞

天文学家发现星系中有3个超大质量黑洞

While supermassive black holes at the heart of galaxies are thought by astronomers to be fairly ubiquitous throughout the universe, researchers studying one nearby example have discovered not one, but three of these cosmic giants.

虽然天文学家认为星系中心的超大质量黑洞在整个宇宙中相当普遍，但研究附近一个例子的研究人员发现了不止一个，而是三个这样的宇宙巨人。

Astronomers probing the center of the galaxy NGC 6240 have discovered three supermassive black holes caught in an elaborate (and doomed) dance around each other. (Photo: ESA/Hubble [CC by 4.0]/Wikimedia Commons)

The galaxy in question, labelled NGC 6240, is actually an amalgamation of smaller galaxies on a collision course with one another. Owing to its irregular butterfly shape, it was initially thought the merger underway was between only two galaxies. Instead, after new observations by the European Southern Observatory's Very Large Telescope (VLT) in Chile, the international team research team was surprised to discover the presence of three supermassive blackholes in tight proximity to one another.

这个被称为NGC 6240的星系实际上是一些小星系相互碰撞的融合体。由于其不规则的蝴蝶形状，它最初被认为只有两个星系在合并。相反，在智利的欧洲南方天文台的甚大望远镜进行了新的观测之后，国际研究小组惊奇地发现了三个紧挨在一起的超大质量黑洞。

"Up until now, such a concentration of three supermassive black holes had never been discovered in the universe," Dr. Peter Weilbacher of the Leibniz Institute for Astrophysics Potsdam (AIP) and co-author of a paper published in the journal Astronomy & Astrophysics said in a statement. "The present case provides evidence of a simultaneous merging process of three galaxies along with their central black holes."

波茨坦莱布尼茨天体物理研究所(AIP)的彼得·威尔巴赫博士在一份声明中说:“到目前为止，在宇宙中还从未发现过三个如此密集的超大质量黑洞。”“目前的情况提供了三个星系及其中心黑洞同时合并过程的证据。”

A cosmic tango of epic proportions

史诗般的宇宙探戈

The irregular galaxy NGC 6240. The northern black hole (N) is active and was known before. The zoomed-in new high-spatial resolution image shows that the southern component consists of two supermassive black holes (S1 and S2). (Photo: P Weilbacher (AIP), NASA, ESA, the Hubble Heritage (STScI/AURA)-ESA/Hubble Collaboration, and A Evans (University of Virginia, Charlottesville/NRAO/Stony Brook University))

New insights into NGC 6240 come courtesy of the VLT's 3D MUSE Spectrograph, an advanced instrument that operates in the visible wavelength range and allowed researchers to peer deep into the galaxy's dusty heart some 300 million light-years away from Earth. Each of the supermassive black holes has a mass of more than 90 million suns and resides in a region of space less than 3000 light-years across. For comparison, the supermassive black hole at the center of our own Milky Way, Sagittarius A*, has a mass of "only" 4 million suns.

VLT的3D MUSE光谱仪提供了对NGC 6240的新见解，这是一种先进的仪器，可以在可见波长范围内工作，使研究人员能够深入观察距离地球约3亿光年的星系尘埃中心。每一个超大质量黑洞的质量都超过9000万个太阳，它们所处的空间跨度不到3000光年。相比之下，银河系中心的超大质量黑洞人马座A*的质量“只有”400万个太阳。

Based on the close quarters of the three supermassive black holes, it's estimated the trio will eventually merge into one sometime over the next several hundred million years.

根据三个超大质量黑洞的近距离，估计这三个黑洞最终会在未来几亿年内合并成一个。

The research team says discoveries such as this one are crucial to understanding the evolution of galaxies over time. Up until now, it was regarded as a bit of a mystery as to how some of the largest galaxies observed, such as the six million light-year-wide giant IC 1101, could have possibly formed over only 14 billion years of the universe's existence.

研究小组表示，像这样的发现对于理解星系随时间的演化是至关重要的。到目前为止，对于一些被观测到的最大的星系，比如600万光年宽的巨型星系IC 1101，是如何可能在宇宙存在的140亿年里形成的，这还被认为是一个谜。

"If, however, simultaneous merging processes of several galaxies took place, then the largest galaxies with their central supermassive black holes were able to evolve much faster," Weilbacher adds. "Our observations provide the first indication of this scenario."

“然而，如果同时发生几个星系的合并过程，那么最大的星系和它们的中心超大质量黑洞能够进化得更快，”Weilbacher补充说。“我们的观察为这种情况提供了第一个迹象。”