A colossal eruption of X-rays observed in 2006 was suspected to be the spill of a black hole of intermediate mass – 50,000 times the mass of the Sun – as it tore and devoured a star. By eliminating a major competing hypothesis, researchers are now confident that they are on the right track, and that is a big problem.
Black holes are mysterious at best. Because they do not emit light, we cannot see them, and we must measure their properties according to the effect they have on the objects around them – whether they are objects in orbit or objects they accrete, a process that generates a lot of heat and light.
But black holes of intermediate mass go up the ante mystery. Because although we have found black holes of really titchy stellar mass (up to 100 times the mass of the Sun) and supermassive black holes really chonky (more than 100,000 times the mass of the Sun, although they can become much larger), the weight the class between the two has proven to be extremely difficult to achieve.
We have had indications that black holes of intermediate mass exist, but nothing conclusive. This new article, according to its authors, is the best evidence to date.
This proof is based on a huge X-ray rocket called 3XMM J215022.4−055108 (or J2150−0551 for short). While the light show had been going on for three years already, the flare was first detected in 2006 by two powerful space X-ray telescopes – NASA’s Chandra X-ray Observatory and the multi-mirror mission to European Space Agency (XMM-Newton) X-rays. ).
In 2018, physicist and astronomer Dacheng Lin of the University of New Hampshire and his colleagues published an article based on the observations of these telescopes. The rocket, they concluded, was probably blown radiation as a black hole of intermediate mass devoured a star.
Now Lin and his team have obtained and analyzed new multi-wavelength observations from XMM Newton and the Hubble Space Telescope. And they are safer than ever that is what caused the push.
“Intermediate mass black holes are very elusive objects, so it is essential to examine them carefully and rule out other explanations for each candidate,” said Lin. “This is what Hubble allowed us to do for our candidate. “
One of the curious things about J2150−0551 was its location – not in the center of a galaxy, where you would normally find large black holes ripping apart the stars. In fact, it appeared to come from a star cluster on the outskirts of a lenticular galaxy 800 million light years away.
This is consistent with one of the training models for intermediate mass black holes which also explains why they are so difficult to find.
A 2004 article suggested that the gravity of a dense star cluster could cause the stars to fall inward toward the center of the cluster, forming a star as massive as thousands of suns. This would then collapse under its own weight, forming a black hole of intermediate mass.
But, as it is extremely difficult to resolve individual stars outside the Milky Way, let alone tracking their orbits, black holes outside the Milky Way are only detectable when material, like a star or a cloud of gas actively falls into it.
By the time one of these star clusters has created a black hole, it would have cleaned the area within its gravitational range, which means that there is no more material nearby to devour, except of the rare and occasional star. This is what astronomers think J2150−0551 was caused by.
And there was always a possibility that J2150−0551 was something else – a neutron star inside the Milky Way that cools after being heated during an accretion explosion – melting material from another star . An accretion explosion large enough to cause this warming in a neutron star had not been detected in an all-sky study that should have detected it, but we needed a more conclusive decision.
Hubble was pointed at the part of the sky in which J2150−0551 was seen to obtain deep and high resolution imagery to confirm its location. These observations confirmed that the X-ray glow did not emanate from the Milky Way, but the star cluster 800 million light years away.
Meanwhile, XMM Newton has obtained more X-ray observations.
“The addition of new X-ray observations has allowed us to understand total energy production,” said astronomer Natalie Webb of the University of Toulouse in France. “It helps us understand the type of star that has been disturbed by the black hole. “
These observations led the researchers to conclude that the eruption was caused by a black hole of intermediate mass while it captured, shredded and lashed a small star of main sequence around a third of the mass of our Sun and about 40% of its size.
They also found that the star cluster itself could be the heart of a dwarf galaxy, stripped of most of its material due to gravitational interactions with the largest galaxy it borders.
Above all, the discovery reaffirms that star clusters orbiting more massive galaxies could be a prime location for finding these elusive intermediate mass black holes.
The research was published in The Astrophysical Journal Letters.