Black holes are the universe’s most unusual entities. The mysterious objects are areas of spacetime exhibiting such strong gravitational acceleration that nothing – even light – can escape. But although black holes are among the most massive objects in existence, there are now known to be more diminutive variations of the impossibly powerful spacetime regions.
A team of astronomers set out to measure the black hole at dwarf galaxy NGC 4395’s centre and were shocked to learn the black hole was 40 times smaller than previously calculated.
This adds a new member to the family of black holes we have information about
Professor Elena Gallo
But despite being so tiny, this particular black hole is still 10,000 times the mass of the Sun.
Measuring this shockingly small black hole is important to astronomers, as it adds to our understanding of what occurs in smaller galaxies.
The current theory is that a supermassive black hole sits at the centre of all galaxy as big or larger than our solar system, the Milky Way.
Professor Elena Gallo, an University of Michigan astronomer said: “This regime of dwarf galaxies is largely unexplored when it comes to the properties of their nuclear black holes.
“We don’t even know if every galaxy has a black hole.
“This adds a new member to the family of black holes we have information about.”
Professor Gallo is co-author of a paper detailing the shock findings that was published on yesterday in the journal Nature Astronomy.
The astronomer says having data on the size of smaller black holes will also help explain the mystery of how some supermassive black holes seem to have an outsized effect on their galaxies.
These somehow make their presence “known” beyond the reach of their gravitational pull.
She added: “There is no reason why stars that live at orders of magnitude larger than the area where black hole gravity dominates should even know that there’s a black hole in their galaxy, but somehow they do.”
Seeing if this phenomenon happens with smaller galaxies and their black holes may help unravel the mystery.
In order to work out the mass of the black hole, the scientists used a method known as “reverberation mapping.”
This involves measuring the radiation emitted from a ring of matter surrounding the black holes known as an “accretion disk.”
Intriguingly, this black hole is the smallest ever found using this technique.
According to the researchers, the latest findings expand our knowledge of black holes and their companion galaxies, especially when it comes to understanding the relationship between the two.
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