Astronomers detect moving supermassive black hole – unusual movement so far unexplained

Scientists have long speculated that supermassive black holes can roam space – but catching them red-handed has proven difficult.

Now researchers at the Center for Astrophysics | Harvard & Smithsonian have identified the clearest case to date of a supermassive black hole moving. Their results are published today (March 12, 2021) in The astrophysical journal.

“We don’t expect the majority of supermassive black holes to move; they usually just sit there, ”says Dominic Pesce, an astronomer at the Center for Astrophysics who led the study. “They are so heavy that it is difficult to move them forward. Consider how harder it is to throw a moving bowling ball than it is to hit a soccer ball – knowing that in this case, the “ bowling ball ” is several million times the mass of our Sun. It’s going to require a pretty powerful kick.

Pesce and his collaborators have worked to observe this rare event for the past five years by comparing the speeds of supermassive black holes and galaxies.

“We asked: are the speeds of black holes the same as the speeds of the galaxies in which they reside?” he explains. “We expect them to have the same speed. If not, it means the black hole has been disturbed.

For their research, the team first studied 10 distant galaxies and supermassive black holes at their nuclei. They specifically studied black holes that contained water in their accretion discs – the spiral structures that turn inward toward the black hole.

As the water revolves around the black hole, it produces a laser-like beam of radio light called a maser. When studied with a combined array of radio antennas using a technique known as very long base interferometry (VLBI), masers can help measure the speed of a hole very accurately. black, explains Pesce.

The technique helped the team determine that nine of the 10 supermassive black holes were at rest – but one stood out and appeared to be in motion.

Located 230 million light years from Earth, the black hole is at the center of a galaxy named J0437 + 2456. Its mass is about three million times that of our Sun.

Using follow-up observations with the Arecibo and Gemini observatories, the team has now confirmed its first results. The supermassive black hole is moving at a speed of about 110,000 miles per hour inside the galaxy J0437 + 2456.

But the cause of the movement is not known. The team suspects that there are two possibilities.

“We may be observing the consequences of the merger of two supermassive black holes,” said Jim Condon, a radio astronomer at the National Radio Astronomical Observatory who participated in the study. “The result of such a merger can push back the newborn black hole, and we can watch it recede or as it re-establishes itself.”

But there is another possibility, perhaps even more exciting: the black hole may be part of a binary system.

“Despite all the expectations that they really should be out there in some abundance, scientists have struggled to identify clear examples of binary supermassive black holes,” Pesce says. “What we might see in the galaxy J0437 + 2456 is one such pair of black holes, the other remaining hidden from our radio observations due to its lack of maser emission.”

However, further observations will ultimately be needed to identify the true cause of the unusual movement of this supermassive black hole.

Reference: “A Restless Supermassive Black Hole in the Galaxy J0437 + 2456” by Dominic W. Pesce, Anil C. Seth, Jenny E. Greene, James A. Braatz, James J. Condon, Brian R. Kent and Davor Krajnović, March 12, 2021, The astrophysical journal.
DOI: 10.3847 / 1538-4357 / abde3d

Co-authors of the new study are Anil Seth of the University of Utah; Jenny Greene from Princeton University; Jim Braatz, Jim Condon and Brian Kent of the National Radio Astronomical Observatory; and Davor Krajnović of the Leibniz Institute of Astrophysics in Potsdam, Germany.