Hubble spots a black hole that should not exist

Conventional wisdom dictates that most large galaxies have supermassive black holes at their center. Scientists also believe that only "active" galaxies should have a visible material accumulation disk, but the Hubble Space Telescope has found one around a black hole with unusual brightness. This galaxy may be a bit of a departure from the rules, but it offers an opportunity to study how the theory of relativity applies in the real world.

NGC 3147 is a large spiral galaxy a little smaller than our own Milky Way. It's about 120 million light-years away – you've probably seen some pictures because it's pretty amazing. Active galaxies such as quasars are easy to spot. The material that falls there produces emissions over the entire electromagnetic spectrum, and the accretion disks are well visible. Everyone thought that NGC 3147 was way too dark to have its own record, but a new analysis from an international team suggests the opposite.

Hubble has collected data on the central black hole of NGC 3147, which is about 250 million times larger than our sun. The object turns out to have a thin disk of material similar to what you have found around an active galactic core. Hubble's observations show that the disk rotates at about 10% of the speed of light. Researcher Stefano Bianchi of Università degli Studi Roma Tre in Italy explains that this discovery indicates that current models of low-light galaxies have "clearly failed".

This discovery could have profound effects on how we model galaxies and black holes, but could also provide a better understanding of the physics behind supermassive objects. The fast disk associated with the apparent low luminosity of the NGC 3147 could test both general relativity and special relativity.

General relativity deals with the mechanisms of gravity in the universe and the special relativity describes the relationship between space and time. Since NGC 3147 is weaker than a typical active galaxy, we can distinguish much better the accretion disk that surrounds it. The disc lies within the powerful gravity field of the black hole, where scientists can study the effects of light.

According to the findings of NGC 3147, astronomers could now go in search of other weakly active galaxies. Some may even be closer to Earth where we can make even more accurate measurements to test Einstein's theories.

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