When Three's A Crowd

 A billion light-years from Earth, a rare and exotic "dance of death" is being performed by a trio of supermassive black holes, doomed to merge along with their host galaxies that are on a collision course. Supermassive black holes, that weigh-in at an incredible millions to billions of times solar-mass, are thought to lurk hungrily in the hearts of perhaps every large galaxy in the observable Universe--including our own barred-spiral Milky Way. When galaxies collide, their supermassive hearts of darkness meet-up as well, and become a single, solitary gravitational beast that weighs-in at the combined masses of the merging black holes that created them. In September 2019, a team of astronomers announced that they have discovered a rare system composed of three galaxies colliding--and taking their resident dark hearts along with them for the ride. Several observatories, including NASA's Chandra X-ray Observatory, as well as other NASA spacetelescopes, discovered this exotic system as a result of scientific serendipity.

"We were only looking for pairs of black holes at the time, and yet through our selection technique, we stumbled upon this amazing system. This is the strongest evidence yet found for such a triple system of activity feeding supermassive black holes," noted Dr. Ryan Pfeifle in a September 26, 2019 Chandra Observatory Press Release. Dr. Pfeifle, who is of George Mason University in Fairfax, Virginia, is the first author of a new paper published in The Astrophysical Journal describing these results.

The unusual system is dubbed SDSS J084905.51+111447 2--SDSS J0849+1114 for short.

Danse Macabre

Because they lurk in the secretive hearts of perhaps every large galaxy in the observable Universe, supermassive hearts of darkness are common denizens of the Cosmos. Indeed, our own Milky Way Galaxy has its own resident supermassive black hole. The Milky Way's central gravitational monster is currently dormant, and it is a relative lightweight--at least as far as supermassive black holes go--weighing-in at mere millions (as opposed to billions) of solar masses.

Our Milky Way's secretive dark heart has been dubbed Sagittarius A* (Sgr A*, for short), and it is on a collision course with another large galaxy. In about 4 billion years or so, our Galaxy is predicted to suffer a titantic collision with the Andromeda galaxy, which is another spiral galaxy of similar size. When this catastrophe occurs, the two supermassive black holes situated in the centers of both galaxies, will also merge. The resulting beast, born from this collision, will weigh-in at the combined mass of the two separate entities that merged to create it.

Our Cosmos is not a peaceful place. Supermassive dark hearts lurk hungrily within their host galaxies, waiting for a feast to come tumbling into their powerful and irresistible gravitational snatching claws. Anything luckless enough to wander too close to one of these frumious bandersnatches of the Universe will become its dinner. Captured victims cannot free themselves from the incredibly powerful gravitational embrace of the predatory black hole. Even light cannot liberate itself if it passes the terrible point of no return called the event horizon.

Doomed stars and clouds of unfortunate gas are some of the tidbits snared by the galactic hearts of darkness. These tragic objects swirl down, down, down as they tumble into the maelstrom of the relentless vortex surrounding the beast--and they will never, never, never return to the outside once they reach the event horizon. As the material travels towards its inevitable end, it creates a ferocious storm composed of glaring matter encircling the black hole--the massive, brilliant accretion disk. In the primordial Universe, these glaring disks dazzled Spacetime in the form of quasars. It is believed that Sgr A* (pronounced saj-a-star) experienced a brilliant quasar stage billions of years ago, when both it, and the Universe itself, were young.

The glaring material that makes up the accretion disk grows ever hotter, as it triggers a raging storm of radiation--especially as it swirls ever closer to the terrible event horizon. The event horizon is located at the innermost portion of the accretion disk.

Although supermassive black holes hide in the hearts of large galaxies, they are not the only members of their bizarre kind. Indeed, black holes come in different sizes. Squeeze enough mass into a small enough space and a black hole will form every time. Smaller black holes of stellar mass are born when an especially massive star runs out of its necessary supply of nuclear-fusing fuel and blasts itself to smithereens in a brilliant core-collapse (Type II) supernova explosion. Intermediate size black holes are also thought to be denizens of the Cosmos and, perhaps, when these middle-weights merge, their supermassive counterparts are born.

In the 18th century, the English scientist John Michell (1724-1793) and the French physicist Pierre-Simon Laplace (1749-1827) proposed that strange beasts like black holes could really lurk in the Universe. Decades later, Albert Einstein, in his Theory of General Relativity (1915), predicted the true existence of such objects. However, at the time, the idea that entities possessing gravitational fields so powerful that nothing could escape from their clutches, seemed so preposterous that Einstein rejected the concept--even though his own calculations suggested otherwise.