Everything in the universe moves, but you usually expect things to be in a certain place. Planets are mostly found around stars and supermassive black holes are at the center of galaxies. So when we discover objects outside these expectations, we know that something interesting is going on. Like in this case.
An international team of astronomers has discovered a very bright variable X-ray source, which has all the characteristics of a supermassive black hole. Surprisingly, it is not located at the center of its galaxy and the researchers think this could be a rare example of a wandering black hole.
The object, classified as XJ1417+52 and found in the galaxy GJ1417+52 4.5 billion light-years away, is estimated to be 100,000 times the mass of the Sun, right on the cusp between an intermediate-sized black hole and the monsters that live at the core of galaxies.
The team observed a special region of the galaxy between 2000 and 2015, called the Extended Groth Strip, using ESA’s XMM-Newton space observatory and NASA's Chandra space telescope. There they discovered a hyper-luminous X-ray source towards the galaxy's edge.
The object was brightest between 2000 to 2002, while in the latest observations it appeared to be at least 100 trillion times less luminous. The researchers suggest that the black hole might have encountered a star and ripped it apart. The debris from the star would then have been heated by the intense gravitational pull, shining brightly in X-rays.
GJ1417+52 is a lenticular galaxy, an object in-between a spiral and elliptical galaxy. It doesn’t appear particularly peculiar, but the researchers think that it might have experienced a minor merger event. A smaller galaxy might have gotten too close to GJ1417+52 and was eaten.
In their study, published in The Astrophysical Journal, the team suggests that XJ1417+52 might be the core of the eaten galaxy slowly moving through the larger one.
Regardless of its wandering nature, XJ1417+52 remains a remarkable object. It is between 10,000 and 100,000 times brighter in X-rays than stellar black holes, making this object 10 times more luminous and 10 times more distant than the previous wandering black hole record holder.