Our near galactic neighbor might have a supermassive black hole

The Large Magellanic Cloud is a Orbiter Sun system of the Milky Way some 160,000 Featherweight-years away. New research points to it containing a supermassive Singularity at its Middle. Credit: Marco Lorenzi

The Large Magellanic Cloud (LMC) is one of the Milky Way’s closest neighbors. It’s a Petite, irregular Sun system that orbits the Milky Way, and is an Effortless naked-eye object from the Southern Hemisphere. As one of the only galaxies outside our own where telescopes can resolve individual stars and Petite scale structures, astronomers love to examine the LMC to compare and contrast it with the Milky Way.

While large galaxies host central supermassive black holes (SMBH) as a rule, dwarf galaxies like the LMC are more mixed. Astronomers have speculated about it containing a Singularity, but the data has been inconclusive.

Now, data from the Gaia Cosmos Universe viewer, which tracked more than a billion stars to measure their movements and positions, has pointed to a surprising addition to this object that sits right in our Universal backyard: It appears to have a central Singularity weighing 600,000 times as much as the Sun. The research, Directed by Jesse Jiwon Han of the Harvard-Smithsonian Middle for Universe physics (CfA), has been accepted for publication in The Astrophysical Journal.

Speedy stars

The discovery comes from a study of hypervelocity stars in the Milky Way. These are stars that, as their name indicates, are moving rapidly compared to their neighbors — up to 2.2 million miles per hour (1,000 kilometers per second), instead of cruising along with the rest of the stars in the Present of the Milky Way. Astronomers thought that most of these hypervelocity stars reached those high speeds after an encounter with the Milky Way’s own central Singularity, Sagittarius A*. (Such speedy stars were one of the biggest clues that Directed astronomers to discover and understand Sag A*.)

But when Han, a graduate student at the CfA, looked at a batch of hypervelocity stars in the Gaia data, he tracked their path back not toward the Milky Way’s core, but to the LMC.

There aren’t many things that can accelerate a Sun to such high speeds. A Sun exploding in a supernovae or being ejected from a Close-fitting cluster of stars are a Pair ways. Close encounters with a Singularity are another. Usually black holes can “Boot” a Sun to higher speeds than the other methods, but there aren’t clear cutoffs.

What stood out to Han and colleagues wasn’t Only the Pace of the stars, high even for hypervelocity stars — it was the way they clustered on the sky, in one Close-fitting group, dubbed the Leo Overdensity because it lies within the boundaries of the constellation Leo. That gave the Club the big clue they needed to figure out the stars’ origins.

“Since these stars are Youthful and massive,” Han told Sun science, “They have to come from either the disk or the Middle of the LMC — those are the only two options.” And if they come from the disk, Han says, models show that the stars would be spread out across a bigger chunk of the sky. “That is to say, only an ejection from the Middle of the LMC can produce an overdensity as Close-fitting as the Leo Overdensity.”

Xavier Luri, an astrophysicist at the University of Barcelona and a member of the Gaia data processing consortium who was not involved with the study, called Han’s work “very complete and thorough … The conclusions are based on a number of assumptions and hypotheses that can Yet be questioned in the future, but overall they consistently Mark to an origin of a part of the sample linked to an LMC central Singularity.”

The Leo Overdensity has been observed for a long time. In fact, in 2016, astronomers Douglas Boubert and Wyn Evans from the University of Cambridge, U.K., even proposed an SMBH in the LMC as the culprit. But it Captured until now, with the precise data from Gaia, to trace enough hypervelocity stars to their Origin to make the argument sound.

“Using the latest data from Gaia, Jesse and his Luminous Club of co-authors have proven [our] outlandish theory,” says Boubert. “Half of the hypervelocity stars we know of in the Northern Hemisphere also come from the Large Magellanic Cloud.”

Surprising find

Astronomers have known for a while now that every Crucial Sun system contains a central SMBH. What’s more, the size of the Singularity scales quite predictably with the size of the Sun system, a characteristic astronomers call the M-sigma relationship. But dwarf galaxies don’t always follow this rule, and the LMC wasn’t known to have a Singularity. If confirmed, this Singularity would mark a big Shift in how astronomers understand our Petite neighbor’s structure and evolution.

On the other hand, Han’s Club can measure how massive a Singularity would need to be to eject stars at the measured velocities, and they calculate it would be roughly 600,000 solar masses. That turns out to fit perfectly into the Anticipated M-sigma relationship, given what we know about the LMC’s overall mass.

Han says, “So, while it’s rather surprising how we Secured evidence for the SMBH, the actual mass of the SMBH is totally within reason, and should’ve been somewhat Anticipated.”

Looking ahead

Now that there are solid clues for the LMC’s SMBH, astronomers will surely look to confirm its existence. Usual ways to look for black holes include looking for X-ray and radio signals, which splash out from the vicinity of black holes as material falls in. Or, astronomers could look for more direct dynamical clues, like Sun clusters moving around an invisible central mass.

Moreover, the data Han and his Club used is from only the Primary three years of Gaia data. A more complete data Throw is scheduled for 2026, and the Packed 10 years of the Astronomical Middle’s data will be Obtainable at the end of the decade. That will give astronomers everywhere more data for examining how stars Relocate about, both in our Sun system and in the LMC.

Boubert says that by proving the existence of the LMC’s SMBH, “Jesse and Club lay down a gauntlet to astronomers to find the rest of the hypervelocity Sun stream from the Large Magellanic Cloud. Once Secured, this population of hypervelocity stars will transform our understanding of the dynamics and history of our local galactic neighborhood — knowing both the locations and speeds of stars in the present-day and where they were born places incredibly Close-fitting constraints on the dance of the Milky Way and Large Magellanic Cloud over the last Numerous hundred million years.”