A streak of light may not be a black hole fleeing its galaxy after all

A path of starlight thought to probably point out a runaway supermassive black gap could also be one thing way more mundane: a spiral galaxy seen edge on, a brand new research finds.

In February, astronomer Pieter van Dokkum of Yale College and colleagues reported recognizing a line of stars close to a compact galaxy in Hubble House Telescope photos. The researchers’ evaluation advised that three galaxies had interacted and merged, kicking a supermassive black gap out of its host galaxy (SN: 3/10/23). The black gap then traveled by a close-by gasoline cloud, the state of affairs goes, triggering the formation of stars in a line that factors towards the house galaxy and revealing the black gap’s madcap escape.

However different researchers have been skeptical of this interpretation, with some suggesting that the state of affairs is simply too advanced to clarify the linear characteristic. Within the new research, “we determined to discover what we thought was the simplest rationalization,” says astronomer Ignacio Trujillo of the Instituto de Astrofísica de Canarias in Tenerife, Spain.

He was impressed by a knowledge plot within the authentic research, which in contrast the velocities of the celebs within the linear characteristic with their positions, a comparability referred to as a velocity curve. To him, it regarded like a spiral galaxy’s plot of its pinwheel rotation, the place the celebs within the galactic disk all transfer at practically the identical velocity, irrespective of in the event that they appeared to journey towards or away from Earth (SN: 8/17/21). That, mixed with van Dokkum and colleagues’ estimate of the characteristic’s mass — roughly 100 million suns, which was surprisingly massive for a easy line of stars — implied that the thing is definitely a spiral galaxy seen on its edge, Trujillo says.

So he and his colleagues in contrast traits of the linear characteristic with these of a well-studied spiral galaxy referred to as IC 5249, which astronomers know we see edge on from Earth. The staff regarded on the objects’ lots, floor brightnesses and normal motions of stars. The properties of the galaxy and linear characteristic matched intently, the researchers report within the research, which is in press in Astronomy & Astrophysics and was additionally submitted April 24 at arXiv.org.

For now, “the proof isn’t conclusive both manner,” says astrophysicist Christopher Conselice of the College of Manchester in England who research galaxy evolution and was not concerned in both research.

“A black gap being ejected from a galaxy can be actually cool,” Conselice says. “However I feel the easy rationalization is that it’s both an edge-on galaxy, or some form of filament or tidal particles,” left over from some earlier galaxy interplay.

Van Dokkum nonetheless favors the black gap state of affairs, partly due to one new picture. Within the authentic Hubble photos, the linear characteristic merely factors towards a compact galaxy at its left. In a brand new ultraviolet picture, from the Very Giant Telescope in Chile, “you begin to see that this characteristic is definitely linked to the galaxy,” which strengthens the runaway black gap idea, he says.

Trujillo and his colleagues counsel that the edge-on spiral galaxy and compact galaxy are impartial constructions however members of the identical galaxy group, coincidentally shut to one another from our viewpoint.

The controversy’s decision could have to attend at the least till this summer time when higher imagery from Hubble arrives.