A supermassive black hole in an ultra-compact dwarf galaxy - Nature
Quote:
Originally Posted by Rachel Feltman, Washington Post
A supermassive black hole has been spotted in the tiniest galaxy yet -- an ultracompact dwarf galaxy -- which suggests that black holes could be in places we haven't even thought to look yet.
The galaxy, named M60-UCD1 and reported in a new Nature study, is 0.2 percent the size of the Milky Way, but contains a black hole with the mass of 21 million suns. That's 15 percent of the galaxy's total mass, which is pretty staggering compared to the less than .01 percent taken up by the Milky Way's personal black hole.
Originally Posted by Seth et. al, Nature 18 Sep 2014
Ultra-compact dwarf galaxies are among the densest stellar systems in the Universe. These systems have masses of up to 2 × 10**8 solar masses, but half-light radii of just 3–50 parsecs. Dynamical mass estimates show that many such dwarfs are more massive than expected from their luminosity2. It remains unclear whether these high dynamical mass estimates arise because of the presence of supermassive black holes or result from a non-standard stellar initial mass function that causes the average stellar mass to be higher than expected. Here we report adaptive optics kinematic data of the ultra-compact dwarf galaxy M60-UCD1 that show a central velocity dispersion peak exceeding 100 kilometres per second and modest rotation. Dynamical modelling of these data reveals the presence of a supermassive black hole with a mass of 2.1 × 10**7 solar masses. This is 15 per cent of the object’s total mass. The high black hole mass and mass fraction suggest that M60-UCD1 is the stripped nucleus of a galaxy. Our analysis also shows that M60-UCD1’s stellar mass is consistent with its luminosity, implying a large population of previously unrecognized supermassive black holes in other ultra-compact dwarf galaxies.
