black hole
September 5, 2017

Have astronomers found the ‘missing link’ of black hole evolution?

Astronomers believe that they have discovered an enormous new black hole thought to be nearly 100,000 more massive than the sun near the center of the Milky Way, and it may be the first ever actual detection of a long-hypothesized-but-never-proven type of space-time phenomena.

Writing in the journal Nature Astronomy, a team of researchers led by Tomoharu Oka of Japan’s Keio University explained that they were analyzing a cloud of molecular gas located close to the center of the galaxy when they noticed that the gases were exhibiting unusual behavior.

According to Time and Newsweek, those gases (which moved at different speeds and included molecules such as carbon monoxide and hydrogen cyanide) appeared to be moved by powerful gravitational forces. So, using computer-based simulations, they determined that the most likely cause would be a “gravitational kick” caused by an object similar to a black hole.

Specifically, they found that the molecules were being influenced by an “invisible compact object with a mass of about 105 solar masses,” which would be indicative of an intermediate-mass black hole (IMBH) – a hypothetical class of black hole in the 100 to 1 million solar mass range which would fall in between stellar black holes and their supermassive siblings.

If their discovery can be confirmed, it would be the first ever evidence of an IMBH, which have long been viewed as the “missing link” in the evolution of these massive objects. Their findings could help explain exactly how supermassive black holes actually form, The Guardian noted.

Additional research needed to verify the discovery

The smallest black holes, stellar black holes, form when certain types of stars explode at the end of their life cycles, but scientists are unsure how supermassive black holes form. One theory, The Guardian said, is that smaller black holes eventually merge together to form larger ones.

The problem with that theory is that while astronomers have discovered many, many stellar and supermassive black holes, they had never been able to locate even a lone intermediate-mass one. The newly-detected signal, Time said, may be coming from the core of a one-time dwarf galaxy that was consumed by the Milky Way. If so, that would seem to support the merger-based theory of supermassive black hole formation, but confirmation will require additional analysis.

In an interview with The Guardian, Brooke Simmons of the University of California, San Diego Center for Astrophysics and Space Sciences said, “We know that smaller black holes form when some stars die, which makes them fairly common... [and] we think some of those black holes are the seeds from which the much larger supermassive black holes grow.”

“That growth should happen in part by mergers with other black holes and in part by accretion of material from the part of the galaxy that surrounds the black hole,” added Simmons, who was not involved in the new study. “Astrophysicists have been collecting observational evidence for both stellar mass black holes and supermassive black holes for decades, but even though we think the largest ones grow from the smallest ones, we’ve never really had clear evidence for a black hole with a mass in between those extremes.”

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