Black hole collisions are among the most extreme events in the Universe, including those occurring in the galaxies closest to Earth. The merger usually results in the formation of a single supermassive black hole, like Sagittarius A*, which is located at the center of the Milky Way. Astrophysicists study these events using space telescopes and ground-based observatories. For example, the first ever image of a black hole located in the galaxy M87 was obtained in 2019 by a team of the world's largest gravitational wave detectors – LIGO and Virgo. Since then, research in this area has continued. Scientists recently discovered a galaxy called MCG-03-34-64, in which several supermassive black holes are about to collide.
Black hole collisions also occur when galaxies near the Milky Way merge. Image: scientificamerican.com
Contents
- 1 Cosmic catastrophe
- 2 Future Collision
- 3 Evolution of Galaxies
- 4 New Generation of Telescopes
Cosmic Catastrophe
Using the Hubble Space Telescope (HST), astrophysicists have discovered three bright, visible, and light “hot spots” inside a pair of galaxies that will collide in the very near future. The distance from them to our planet is approximately 800 million light years, which is relatively small in cosmic terms.
Scientists also noted that two of the three “hot spots” are only about 300 light years apart, but the distance to the third “hot spot” could not be determined. It should be noted that the Hubble Space Telescope, a bit of a retiree, recorded the future collision of the galaxy MCG-03-34-64 using an advanced camera.
Astronomers have discovered supermassive black holes near our galaxy that are on the verge of colliding. Image: earth.com
When we looked at MCG-03-34-64 in X-rays, we saw two separate, powerful sources of high-energy radiation, matching the bright optical points of light observed by Hubble. Putting these fragments together, we concluded that we are most likely dealing with two closely spaced supermassive black holes, the astronomers wrote.
The observations showed that stars from two galaxies that had previously collided had mixed, forming two huge black holes. These objects then merged into a single supermassive black hole and formed an entirely new galaxy.
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A research team from the Harvard Center for Astrophysics and the Smithsonian Institution in Cambridge (USA) notes that they did not expect to see something like this: “This type of supermassive black hole is extremely rare in the observable Universe and indicates that something else is happening inside the galaxy MCG-03-34-64,” they concluded.
Future collision
There is no doubt that supermassive black holes discovered on the verge of collision really exist – observations of these objects have been preserved in the archives of the Chandra radio telescope and the Karl G. Jansky Very Large Telescope. Powerful radio emissions from black holes have proven that the objects are approaching each other.
After Hubble's Advanced Camera for Space Telescopes detected three optical diffraction spikes (aka “hot spots”) in the center of MCG-03-34-64, astrophysicists were able to predict that the collision would occur in almost a hundred million years.
Two of the three bright spots are active sources of light and X-rays in the nuclei of galaxies. They point to two supermassive black holes located about 300 light-years apart. Image: NASA/ESA/Anna Trindade Falcão/CfA
Since each of the black holes is located at the center of a separate galaxy, their interaction will occur as they approach each other. Eventually, they will merge, emitting gravitational waves, the authors of the discovery explained.
Astrophysicists have suggested (using simulations and observations) that merging galaxies with supermassive black holes is the cause of intense cosmic activity, with interstellar gas rushing toward the centers of galaxies. This interstellar gas, the researchers note, is also compressed in other regions, leading to bursts of star formation.
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Let us recall that the mergers in question constantly occur in the Universe: models of galaxy evolution, combined with observational data, suggest that many supermassive black holes located in galactic centers undergo this process. Understanding these processes opens up unique opportunities for better understanding the formation and evolution of both galaxies and their enormous “hearts”.
Evolution of galaxies
Although we cannot observe the entire process of cosmic collisions, since they take millions of years to complete, astronomers continue to search for these catastrophic events. The fact is that black hole mergers play a key role in the formation and evolution of galaxies, affecting their rotation speed, the activity of central black holes, and the distribution of stars.
It should be noted that in galaxies with a high density of stars, such as elliptical galaxies, the probability of black hole collisions is higher, and studying the frequency and distribution of mergers of these “space monsters” helps to estimate the age of the Universe and understand the processes of its expansion. And although direct radiation from black hole collisions is difficult to detect, accompanying phenomena (for example, radiation from accretion disks) provide astrophysicists with additional data.
The universe is expanding at an accelerating rate, but the exact reasons why are unknown. Image: scientificamerican.com
It is also important that black hole collisions allow us to test Einstein's general theory of relativity (GTR) under extreme conditions, and the discovery of new types of gravitational waves may even lead to a revolution in understanding fundamental physical laws.
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A new generation of telescopes
Despite the technical difficulties associated with detecting and studying the collision of galaxies and black holes, progress in creating new astronomical instruments opens up new opportunities for scientists. With their help, it will be possible to obtain much more information about the formation of galaxies and other mysteries of the Universe.
For example, the Einstein Telescope is a new generation of instruments and has increased sensitivity. Its work is based on the successes of the Virgo and LIGO laser interferometer detectors.
Another new product, the LISA telescope, will allow recording gravitational waves in a range inaccessible to ground-based detectors. The launch of this project is scheduled for 2034. The instrument will allow detailed study of the centers of galaxies, black holes, and massive stars.
Laser Interferometer Space Antenna — a project to detect gravitational waves in space. Image: lisa.nasa.gov
Also intriguing is the launch of the Roman telescope (aka WFIRST), scheduled for 2027. This successor to the James Webb telescope will focus on studying dark energy and dark matter, as its wide-band cameras allow for large-scale studies of cosmic structures.
Roman will take about 100,000 images per year. The field of view of this instrument is significantly larger than that of Hubble and Webb, – report researchers from the Goddard Center (NASA).
In addition, in 2023, the European Space Agency (ESA) launched the Euclid observatory into low-Earth orbit, whose primary mission is to study the nature of dark energy and dark matter by precisely measuring the distribution of galaxies and weak gravitational lensing.
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The LUVOIR spectral telescope is also under development, the capabilities of which are predicted to surpass all modern analogues. The fact is that this large ultraviolet optical infrared telescope will be able to examine the atmospheric layers of exoplanets, which is important for searching for signs of life outside the Solar System. Its scientific tasks also include the study of Solar System objects, stars, galaxies and the history of the Universe.
NASA's Ultraviolet, Optical, and Infrared Space Telescope Project. Image: asd.gsfc.nasa.gov
In addition to the astronomical instruments mentioned above, other telescopes are also in development to search for exoplanets and study their atmospheres. All of these innovative new products will greatly expand our understanding of space and the Universe, as well as open up new areas of research in astronomy and astrophysics. We can't wait!