An article published in the journal “Nature” describes the discovery of one of the biggles black holes found so far. Using data collected from the Hubble Space Telescope and the Gemini North telescope in Hawaii, an international team of astronomers discovered a supermassive black hole with a mass estimated at around 17 billion times the Sun in the galaxy NGC 1600. It’s an extraordinary mass considering that it’s inside a galaxy very large but fairly isolated.

The galaxy NGC 1600, also known as MCG-01-12-017, H I-158, h 319, GC 866 and PGC 15406, is an elliptical galaxy about 200 million light years from Earth. It’s part of a small group that contains about twenty galaxies and that’s why it wasn’t expected to have such a massive black hole at its center. Put simply, astronomers expect to find very massive black holes at the center of galaxies that are part of galactic clusters,  where there are enough masses to form hundreds or even thousands of galaxies grouped together.

NGC 1600 is part of a small group in what was called a cosmic backwater of ​​the universe, so they expected that the materials that formed the supermassive black hole at its center didn’t have enough total mass to make it one of the most massive ever discovered. It’s about ten times more massive than astronomers expected according to a correlation between the mass of a galaxy and that of the supermassive black hole at its center that generally gives a good approximation.

For this reason, normally this type of research is focused on galaxy clusters. However, in this case the researchers worked within MASSIVE Survey, which aims to estimate the mass of stars, dark matter and black holes of 100 massive galaxies within 350 million light years from Earth.

Professor Chung-Pei Ma of UC Berkeley, one of the authors of the article on the galaxy NGC 1600 and at the head of the MASSIVE Survey, wondered if this galaxy is the tip of the iceberg. Actually, it’s not the first time that astronomers discover supermassive black holes larger than expected. In September 2015 an article was published describing another research on a case of this kind in the SAGE0536AGN galaxy.

Another interesting discovery emerged from this research is that the stars near the supermassive black hole appear to be moving as if there were two black holes. One explanation is that NGC 1600 is the result of a merger of two galaxies and the two supermassive black holes at their centers are getting closer and closer. The consequence is that the 17 billion solar masses are actually the sum of the masses of the two supermassive black holes.

It’s one of the cases in which more data are needed to try to understand what’s really at the center of the galaxy NGC 1600. This type of research is needed to help better understand how galaxies evolve after a merger and how supermassive black holes affect their evolution.