Researchers solve mystery of runaway black hole leaving behind trail of newborn stars

The NASA/ESA Hubble Space Telescope recently spotted a possible runaway supermassive black hole leaving behind a mysterious 200,000-light-year-long contrail of newborn stars - twice the diameter of our home galaxy. Researchers at the Instituto de Astrofísica de Canarias (IAC) have now concluded that the unusually thin structure of stars could be a galaxy without a bulge seen edge-on.

This finding goes against the original interpretation that the speedy black hole is plowing into gas in front of it to trigger new star formation along a narrow corridor.

"The motions, the size, and the quantity of stars fits what has been seen in galaxies within the local universe. It's a relief to have found the solution to this mystery, the new proposed scenario is much simpler. In one sense it is also a pity, because the existence of fleeing black holes is expected, and this could have been the first one to be observed," said Jorge Sanchez Almeida, an IAC researcher who is the first author of this study.

To support this new hypothesis, the team compared the mysterious structure with a well-known local galaxy without a bulge, IC5249. This intergalactic skyrocket and IC5249 turned out to be extremely similar in all their physical parameters, supporting the idea that the unusual structure is really an edge-on galaxy.

According to IAC researchers, these types of galaxies, also called thin, or flat galaxies, are relatively common in the Universe.

"We also looked at the relation between the mass of the assumed galaxy and its maximum velocity of rotation, and discovered that indeed it is a galaxy which behaves like a galaxy," said Ignacio Trujillo, an IAC researcher who took part in the study.

The team has published their findings in the journal Astronomy and Astrophysics Letters. More details can be found here.