Giant ‘Cosmic tail’ Discovered in Galaxy NGC 3627, Potentially Left by Roaming Black Hole
A newly discovered, exceptionally long and well-defined trail of gas and dust in the galaxy NGC 3627 is sparking debate among astronomers, with a leading theory suggesting it was created by a supermassive black hole hurtling through the galactic disk. The structure, described as the clearest and longest ”contrail” ever found outside the Milky Way, stretches for an extraordinary distance and offers a rare glimpse into the dynamic processes shaping galaxies.
The trail appears as a thin, elongated line distinct from NGC 3627’s spiral arms. Researchers believe the phenomenon originated approximately 20 million years ago – a recent event on cosmic timescales, given the milky Way’s age of over 13 billion years. A theoretical model developed in 2021 by researcher Li proposes the trail formed when a dense object around 10 million times the mass of our sun, likely a black hole, traversed the galaxy at roughly 300 kilometers per second (186 miles per second). This high-speed passage would have compressed and swept out gas in its wake,creating the observed ”cosmic tail” and the turbulence detected within it.
“Its length is extraordinary, and its shape is very well defined compared to similar structures in other galaxies,” stated zhao, a researcher involved in the study.
While the black hole hypothesis is currently favored, scientists haven’t ruled out the possibility that the trail could be the remnant of a dense core from a dwarf galaxy passing near NGC 3627.Distinguishing between these scenarios remains challenging with current data. ”If the object is a faint dwarf galaxy, it is too far away to detect directly,” explained Zhao.
The research team, analyzing data from the PHANGS survey, intends to continue searching for similar structures in other galaxies. Thay hope these future discoveries will help map the population of massive, freely moving dark objects – including potentially wandering black holes – and provide new insights into galactic evolution and interactions. “Understanding how frequently enough phenomena like this occur can give us new insights into how galaxies evolve and interact with hidden objects in the universe,” Zhao added.
The findings are currently available as a pre-review publication on the arXiv server.