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Adaptive optics help correct the blurring effect created by the Earth's atmosphere on light. The laser-guided star-adaptive optical system (LGS AO) of the W. M. Keck Observatory uses a laser to create an artificial star to measure atmospheric distortions. The result is sharp, high-resolution images that allow astronomers to see celestial objects, such as fusions of hidden galaxies, in extremely fine detail. PC: Billy Doaner / WM Keck Observatory.
Astronomers recently captured the best views to date of two supermassive black holes on a collision course at the center of molten galaxies. This discovery could help scientists understand how supermassive black holes become so big.
"Seeing the pairs of molten galaxy nuclei associated with" huge "black holes so close to each other was rather astonishing," said lead author Michael Koss, from Eureka Scientific Inc., Kirkland, Washington State. "The images are quite powerful because they are ten times sharper than the images of normal ground telescopes. It's like going from blind vision (20/200 vision) to perfect 20/20 vision when you wear your glasses. In our study, we see two galaxy nuclei just at the moment the images were taken. You can not argue with her; it is a very clear result that does not rest on an interpretation. "
The results of the study were published online November 7, 2018 in the journal Nature.
Koss and his team of researchers made this discovery after completing the largest systematic study of neighboring galaxies using high resolution images taken with the Adaptive Optics System (AO). and the near infrared camera (NIRC2) of the observatory WM Keck. archive images of the Hubble Space Telescope. With the help of data collected by this comprehensive study, astronomers can identify the types of galaxies most likely to house tight pairs of supermassive black holes.
"This is the first major systematic survey of 500 galaxies that really isolated these mergers of late-stage dark holes, very obscured and very bright," said Koss. "This is the first time this population has really been discovered. We have found a surprising number of supermassive black holes that grow and develop more rapidly in the later stages of galaxy fusion. "
These images reveal the final stage of a union between pairs of galactic nuclei in the messy nuclei of colliding galaxies. The image at the top left, taken by Hubble's wide-field camera 3, shows the fused galaxy NGC 6240. A close-up of the two bright hearts of this galactic union is shown at the top right. This sight, taken in infrared light, pierces the dense cloud of dust and gas that envelops the two colliding galaxies and reveals the active cores. The heavy black holes in these nuclei grow rapidly while they feast on gas pushed by the fusion of the galaxy. The rapid growth of black holes occurs during the 10 to 20 million years of fusion. The NGC 6240 images show images of four other colliding galaxies, as well as close-up views of their coalescing nuclei in bright nuclei. Images of the bright nuclei were taken under infrared light by the WM Keck Observatory of Hawaii, using adaptive optics to refine the view. The reference images (left) of the fusing galaxies were taken by the pan-lift telescope and the pan-STARRS. The two cores in the Hubble and Keck observatories are only about 3,000 light-years apart – an almost cosmic embrace. If there are pairs of black holes, they will likely merge in the next 10 million years to form a more massive black hole. These observations are part of the largest survey ever conducted on the hearts of neighboring galaxies with the help of high resolution images in infrared light taken by the Hubble and Keck observatories. The average distance of galaxies studied is 330 million light-years from Earth. CREDIT: NASA / ESA / M. KOSS (EUREKA SCIENTIFIC, INC.) / STARS / W. KECK'S OBSERVATORY
Scientists theorize that each large galaxy hosts a supermassive black hole in its center. When the galaxies fuse, their respective black holes do the same. This process takes billions of years, but ends in seconds. At present, a supermassive black hole fusion has never been observed directly.
It is difficult to find galactic nuclei so close to each other, because the latent stages of a fusion of galaxies attract a lot of gas and dust, especially in the last stages, the most violent, masking the view. Astronomers have been unable to observe this type of event up to now.
"The nuclei of very darkened galaxies do not have a brilliant point source in the center, unlike many bright, unmasked supermassive black holes," Koss said. "But we were able to detect them with the Burst Alert telescope (BAT) X-ray data. We then used the superior laser capability of the Keck Observatory AO system to perform high-resolution near-infrared imaging to distinctly distinguish a dual core through gas and dust and reveal hidden fusions. "
The findings of Koss and his team support the hypothesis that galaxy fusions explain how some supermassive black holes can become so huge.
"There are competing ideas. One idea is that you have a pile of gas in the galaxy that is slowly feeding the supermassive black hole. The other idea is that you need galaxy fusions to trigger significant growth. Our data shows that, for the second case, these galaxy fusions are really essential to fuel the growth of supermassive black holes, "Koss said.
The survey can also help astronomers to observe for the first time a fusion of black holes.
Koss and his team focused on galaxies located at an average distance of 330 million light-years from Earth. Most galaxies are similar in size to the Milky Way. The images suggest what will probably happen in about a billion years when our own galaxy will merge with the neighboring galaxy of Andromeda.
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