The 10 wildest things we learned about black holes in 2021

Faster rotating black hole
Even the best-studied black holes still provide surprises. In February, physicists revised their estimates of the properties of the cosmic monster at the heart of the Cygnus X-1 system, which is also the first confirmed black hole to exist. Originally discovered almost 60 years ago, the Cygnus X-1 black hole was found to be 50% more massive than previously thought, making it 21 times the mass of the sun and rotating very close to the speed of light. , setting a new record for black. hole rotation. The black hole in Cygnus X-1 is about 7,200 light-years away and is slowly consuming a blue supergiant companion star, providing researchers with new insights into such processes.

Spaghetti star seen and simulated
When a star gets too close to the edge of a black hole, gravitational forces pull it apart into long strands that are sucked into the black hole’s jaws. This process, known as “spaghettiification,” produces light as stellar material heats up through friction, allowing astronomers to capture the eerie act in all its glory. In May, researchers first saw a star being crushed and eaten in this way by a black hole that weighed 30 million times the mass of the Sun and was located at the center of a galaxy 750 million light-years away. Earth. In addition to capturing important data on spaghetti, the observations helped scientists create an incredible visualization of stellar ingestion.

LIGO proves Hawking is right

In June, researchers at the Laser Interferometer Gravitational Wave Observatory (LIGO) observed two gigantic black holes merge into a single entity and analyzed ripples in the space-weather fabric called gravitational waves created when black holes spiraled toward each other. another at high speed. They found that the surface area of ​​the resulting black hole was larger than the first two combined. As well as providing astonishing data, the findings help prove a 1971 conjecture by British astrophysicist Stephen Hawking known as the black hole area theorem. The theorem states that it is impossible for the surface area of ​​a black hole to decrease with time, a law that Hawking derived using Einstein’s theory of relativity as well as his understanding of entropy. While the results were a win for Hawking, they leave physicists with a head scratch. According to quantum mechanics, black holes should be able to shrink and evaporate, so it’s unclear how to square that with Hawking’s law that their surface area must also always increase.

Black hole and neutron star merger
LIGO had a slew of black hole finds to deliver in June, when researchers working with the facility announced that, for the first time, they were sure they had seen black holes merging with compact entities called neutron stars. Along with black holes, neutron stars are a possible end result of the death of a massive star, when the star explodes as a supernova and leaves behind a remnant. While LIGO had seen hints of possible neutron star and black hole mergers, it was not until this year that two signals conclusively demonstrated that such mergers were occurring. Both detections occurred in January 2020, approximately 10 days apart. The first involved a black hole with approximately six times the mass of the sun devouring a neutron star one and a half times the mass of the sun, while the second involved a black hole approximately nine times the mass of the sun and a neutron star approximately twice as massive as the sun. Sun.

The early black hole blows a storm

Almost all known galaxies have a supermassive black hole at their center, suggesting that there is a close relationship between the two cosmic entities. But scientists still don’t understand how a black hole affects its galactic host. Research published in June showed high-speed winds coming from a 13-billion-year-old galaxy, one almost as old as the universe itself. This is the first detected example of a galactic wind, blowing out of supermassive black holes as they consume the surrounding gas and dust. In addition, the powerful winds, traveling at about 1.1 million mph (1.8 million km / h), are moving fast enough to propel material across the galaxy and likely hamper star formation. This suggests that the galaxies and their black holes have an ancient and very close link.

Light Echoes Prove Einstein Right
Stephen Hawking wasn’t the only one to rack up black hole victories this year. In July, astronomers captured X-ray flares from a supermassive black hole at the center of a spiral galaxy called Zwicky, which is 1.8 billion light-years away. The researchers not only detected light coming from the front of the black hole, but they also managed to find strange light echoes that they could not initially locate. It turned out that these originated at the back of the black hole, meaning that the mammoth entity was warping the structure of space-time so much that light was being drawn from one side of the black hole to the other. This process is exactly what you would expect from Einstein’s theory of general relativity but, until now, it has not been definitively detected.

Aliens could be using the power of a black hole

Scientists are not above speculating, as long as their guesses are based on relevant data. In August, a team of astronomers in Taiwan suggested that technological aliens could be harvesting energy from black holes using hypothetical megastructures known as Dyson spheres that surround a star. Despite being considered dark, black holes emit large amounts of energy by feeding on surrounding material, which heats up and radiates light. Astronomers wondered if an alien species could place orbiting platforms coated with something like solar panels around a black hole to absorb its energetic blasts. Since black holes are smaller than stars, this would allow aliens to save on building materials and potentially allow them to accumulate incredible amounts of energy.

Wandering black holes could settle in our galaxy

Roughly 12 huge invisible black holes could lurk on the outskirts of the Milky Way. That was the conclusion in August, when the researchers published the results of a new galaxy collision simulation. During such monumental events, gravitational forces could cause supermassive black holes, which weigh millions or billions of times more than the sun, to fly off and roam the dark depths of the cosmos. Some of these may later settle in the halos of galaxies like ours, and a galaxy the size of the Milky Way is expected to host around 12 on average. Astronomers hope to discover how to search for these lost giants to see if their simulations are correct.

The closest pair of black holes is seen

In December, telescopes captured evidence of the closest pair of black holes to our own planet, a duo orbiting each other about 89 million light-years from Earth in the constellation Aquarius. The previous pair of black holes that have records are five times farther away than this one, which means that scientists have the opportunity to study such systems in greater detail than before. Both members of the duo are heavyweights: the largest has a mass of almost 154 million suns, while the smallest is 6.3 million times more massive than our star. They orbit each other a mere 1,600 light-years apart, a pittance in cosmic terms and another record high, indicating that they will merge into a giant black hole 250 million years from now.

A black hole too big for its galaxy.

A small galaxy orbiting our own at a distance of about 820,000 light-years appears to contain a rarity. The dwarf galaxy Leo I, which is 50 times smaller than the Milky Way, is home to a large black hole, one with almost the same mass as the black hole at the center of the Milky Way. Astronomers are puzzled at how such a large black hole came to reside in such a small galaxy. “There is no explanation for this type of black hole in dwarf spheroidal galaxies,” said María José Bustamante, an astronomy graduate from the University of Texas at Austin, in a statement. Finding out precisely what this means for both the black hole and galactic evolution will have to wait for years to come.