Massive black hole in a satellite galaxy; Know about galaxies that orbit Milky Way

An unusually massive black hole has been discovered at the center of one of the Milky Way's many satellite galaxies, according to a new study. The astronomers from the University of Texas (UT) at Austin’s McDonald Observatory found that this black hole is has a mass equivalent to the one at the heart of our galaxy. Located in the galaxy called Leo I, the black hole could redefine our understanding of how the building blocks of the universe, meaning the galaxies, evolve over time. 

It's not the dark matter, but a black hole...

The galaxy Leo I was the center of attraction for the study as it has some very peculiar features. For confirming the presence of a black hole at the galaxy's center, the experts measured Leo I’s dark matter profile and noted that it does not contain much dark matter, unlike other satellite galaxies. A dark matter profile shows how the density of dark matter changes from the outer edges of the galaxy all the way into its center. To get an update on the profile, the researchers measured the gravitational pull on the stars to find out whether the density of dark matter increases towards the galactic center.

Karl Gebhardt, a research team member said as per UT, "The models are screaming that you need a black hole at the center; you don’t really need a lot of dark matter. You have a very small galaxy that is falling into the Milky Way, and its black hole is about as massive as the Milky Way’s. The mass ratio is absolutely huge. The Milky Way is dominant; the Leo I black hole is almost comparable". In simple words, scientists found that the influence on the stars cannot be something created by dark matter and only by a black hole.

Here are some of the satellite galaxies that orbit the Milky Way

To learn about satellite galaxies, it is important to understand what satellite galaxies are in the first place. The suffix satellite is given to those galaxies that are less massive, have their own collection of stars and all orbit their own center. However, these galaxies in turn orbit a massive galaxy just like the planets on our solar system orbit the Sun.

Our galaxy, the Milky Way has a number of satellite galaxies however, some of them are some that are the most talked about. Among the popular ones is the Large Magellanic Cloud which is about 163,000 light-years away and around 1/100th the size of the Milky Way. It has been observed to have a distorted shape as scientists believe that it is being pulled and warped by the influence of the host galaxy. Another is the Sagittarius Dwarf Spheroidal Galaxy which is around 50,000 light-years away from the Milky Way center and orbits over the top and down below the disk of our galaxy. The list also includes the Canis Major Dwarf Galaxy which is closer to our Milky Way than the previous one. Located about 25,000 light-years away, this galaxy is almost at the edge of the Milky Way and is closer to our solar system than the galactic center.

(Image: University of Texas)