With new imagery from the Hubble space telescope, astronomers have found a supermassive black hole at the center of one of the universe’s smallest known dwarf galaxies, raising questions about some of our theories of how the universe was formed.
The supermassive black form at the center of the dwarf galaxy is about four times larger than the black hole that our own Milky Way revolves around – but surprisingly, the dwarf galaxy is five hundred times smaller than the Milky Way, with a diameter of just 300 light years.
“We don’t know of any other way you could make a black hole so big in an object this small,” says Anil Seth, lead author of the new research.
— NASA (@NASA) September 17, 2014
Dwarf galaxy M60-UCD1 consists of about 140 million stars, smashed into a space that’s just 300 light years across. By comparison, our own Milky Way is over 100,000 light years across and consists of about 200 billion stars. According to NASA, if you looked up at the night sky from within the dwarf galaxy you would be able to view at least 1 million stars. On Earth, you can see just a few thousand. The image above features an artist’s rendering of what the night sky might look like in the dwarf galaxy – the galaxy is 50 million light years away and thus too far for Hubble to capture such detail.
While M60-UCD1 is undoubtedly very tiny, it isn’t its diminutive size that makes it notable – it’s the huge supermassive black hole in the middle that has astronomers confused. It’s not unusual for a galaxy to have a supermassive black hole at its center – but it wasn’t thought to be possible for a dwarf galaxy to harbor one. The black hole at the center of the Milky Way has a mass of around four million Suns, or about 0.01% of the galaxy’s entire mass. The M60-UCD1 black hole has the mass of 21 million Suns, or in other words about 15% of the galaxy’s total mass.
“That is pretty amazing, given that the Milky Way is 500 times larger and more than 1,000 times heavier than the dwarf galaxy M60-UCD1,” Seth says.