Astronomers have observed three Supermassive Black Hole (SMBHs) at the center of three colliding galaxies one billion light-years away from Earth. This is unusual in itself, but three black holes can also be seen in X-ray emission.
This is evidence that all three are active galactic nuclei (AGN), which collide and glow. This discovery may shed some light on the “final parser problem”, a long-standing problem in astrophysics and black hole mergers.
Astronomers have found three SBES in data from several telescopes, including the Sloan Digital Sky Survey (SDSS), the Chandra X-ray Observatory, and the Wide-field Infrared Survey Explorer (WISE).
Three black holes have been seen almost wrapped in a unique phenomenon, the merger of three galaxies. These triple mergers can play an important role, such as how massive black holes evolve over time. Astronomers were not expecting to find three black holes at the center of the triple-galaxy merger.
Ryan Pfiffle of George Mason University in Fairfax, Virginia (the first author of a new paper describing the results of these astrophysical journals) said that we were only looking for this pair of black holes, and then through our selection technique, We have been able to find this amazing system.
This is the strongest evidence found for such a triple system of actively blossoming supermassive black holes.
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Triple black hole systems are difficult to find because there is so much going on around them. They are surrounded by gas and dust which makes it challenging to see. In this study, several telescopes were operated in different parts of the electromagnetic spectrum to uncover the three holes, and some local civilian scientists were also assisted in this discovery.
This was not only difficult to spot, but also rare. “Dual and triple black holes are extremely rare,” said George Mason co-author Shobita Satyapal, “but such a system is actually a natural result of galaxy mergers that give us an idea of how the galaxy evolves.”
The SDSS was the first to place this triple-merger in visible light, but it was only through the citizen science project Galaxy Xu from which the galaxies collided as a system.
WISE then noticed that this system was shining in the infrared, indicating that it was in a phase of galaxy merger when more than one black hole was expected to feed.
The Sloan and WISE data were only detecting clues, and astronomers used Chandra observations and large telescope telescopes (LBTs) for further confirmation. Chandra’s data showed that there were bright X-ray sources in the center of each galaxy. Exactly where scientists hope to find SMBH.
More evidence is showing that SBAS came from Chandra and NASA’s Nuclear Spectroscopic Telescope Array (NuSTAR) satellite. They found evidence of large amounts of gas and dust near one of the black holes, which is expected to dissolve the black hole. Other optical light data from SDSS and LBT provided spectral evidence, characteristic of three SMBH feeding.
Optical spectra contain a wealth of information about a galaxy, said co-author Cristina Manzano-King of the University of California, Riverside – they are commonly used to actively identify supermassive black holes and the galaxies they May reflect the effect they inhabit.
With this work, the team of astronomers has developed a way to discover more of these triple black hole systems.
“Through the use of these major observatories, we have identified a new way of identifying triple supermassive black holes. Each telescope gives us a different clue as to what is going on in these systems”. “We hope to expand our work to find more triples using the same technology.” They may have shed some light on the final parser problem.
Last parsec problem
The final parsec problem is central to our understanding of binary black hole mergers. This is a theoretical problem that states that when two black holes contact each other, their excessive orbital energy prevents them from merging. They can then obtain the merger process stall within a few light-years.
When two black holes initially contact each other, their hyperbolic trajectories take them past each other. Over time, as both interact with the stars around them, they gravitate the stars, transferring their orbital energy a few times to a star. The emission of gravitational waves also decreases the energy of a black hole.
Simulation of merger of two black holes and gravitational radiation
Eventually the two black holes shed enough orbital energy to get closer to each other and slowly get closer to each other. The problem here is that as they close the distance, more and more matter is removed from their surroundings through sling-shooting. This means that there is nothing else to interact with a black hole with more orbital energy. At that point, the merging process stalls or it should be.
Yet astronomers know that black holes merge because they have seen powerful gravitational waves. In fact, LIGO (Laser Interferometry Gravitational-Wave Observatory) is exploring black hole mergers once a week. How they merge with each other in the end is called the final parse problem.
The team behind this study feel that they may have an answer. They feel that a third black hole, as they have observed in this system, may provide the necessary boost to merge the two holes.
As a pair of black holes in a sacral system approach each other, the third can influence them to close and merge the final pars.
According to computer simulations, about 16% of the supermassive black holes in colliding galaxies would have interacted with a third supermassive black hole before merging.
They will produce merged gravitational waves, but the problem is that the detection of those waves will be too low a frequency for the LIGO or VIRGO observatory.
Gravitational wave spectrum
To detect them, scientists may have to rely on future observatories like LISA, ESA / NASA’s Laser Interferometer Space Antennas. LISA will observe gravitational waves of lower frequency than LIGO or VIRGO and will be better equipped for super-massive black hole mergers. The paper presenting these results is titled “A Triple AGN in a Mid-Infrared Selected Late Stage Galaxy Merger.”