The galaxies are a component of group of galaxies more than 2 billion light – years from the Earth. The near encounter, millions of years ago, released the smaller galaxy of closely all its gas and stars. What remainare its black hole and a tiny galactic remnant just about 3,000 light – years across. For comparison, our Milky Way Galaxy is only 100,000 light – years across.
The study was made as a component of a program to identify supermassive black holes, billions or millions of times bigger than the Sun that are not just at the centres of galaxies. Supermassive black – holes rest at the centres of most galaxies. Big galaxies are considered to grow by devouring smaller companions. In such situations, the black holes of both are considered to revolve each other, ultimately merging.
“We were searching for orbiting pairs of supermassive black holes, with single offset from the centre of a galaxy, as telltale evidence of a previous galaxy merger,” says James Condon of the National Radio Astronomy Observatory. “Instead, we identified this black hole fleeing from the bigger galaxy and leaving a trail of dust behind it,” he added.
The astronomers started their quest by utilizing the VLBA to prepare very high resolution images of more than 1,200 galaxies witnessed by large-scale sky surveys done with infrared and radio telescopes. Their VLBA observations revealed that the supermassive black holes of all these galaxies were at the centres of the galaxies.
However, one object, in a group of galaxies called XZwcL8193, did not fit well into the pattern. Further studies revealed that such object, known as B3 17175+425, is a giant black hole encompassed by a galaxy much smaller and fainter than would be considered. In addition to this, the object is speeding away from the core of a much bigger galaxy, leaving a wake of ionized gas behind it.
The researchers concluded that the remained or unfit hole is ‘nearly naked’ supermassive black hole. The speeding remnant, the researchers says, probably will lose more mass and cease creating novel stars. “In a billion of years or so, it would be invisible,” Condon says. That implies, he pointed out, that there could be much more such objects left over from previous garlic encounters that astronomers cannot identify.
The researchers will keep searching, however. They are identifying more objects, in a long-term project with the VLBA. Since their project is not time – critical, Condon explains, they utilize ‘filler time’ when the telescope is not in use for other analysis.
“The information we obtained from the VLBA is very high – quality. We get the positions of the supermassive black holed to be extremely good accuracy. Our limiting factor is the accuracy of the galaxy positions seen at the other wavelengths that we utilize for comparison,” says Condon.
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