How Black Holes Continue To Astound Us

NASA’S Chandra Catches Our Galaxy’s Giant Black Hole Rejecting Food

Our Early Ancestors May Have Seen The Milky Way’s Black Hole

Around two million years ago, the supermassive black hole at the center of our galaxy burst into life with a radiant glow. At that time, man was just beginning to walk upright. Our ancestors would have seen a moon-sized light in the southern sky that looked like a bright fuzz ball or smudge.

Our black hole, Sagittarius A*, is quiet now. But back then, it was believed to be an active galactic nucleus (AGN), the energy-producing compact center of a galaxy that greatly outshines the rest of it. 

A feeding black hole may be the source of an AGN as its gravitational pull attracts matter, forming a disk that heats up and glows. If the disk pulls in large amounts of matter, two bright jets of high-energy particles will be cast off from the black hole perpendicular to its spin.

Astronomers devised this AGN theory in 2010 after spotting two Fermi bubbles stretching 25,000 light-years above and below our galaxy. The scientists believe that AGN jets could have produced those bubbles between one and three million years ago. 

The black hole light show would have lasted a few thousand years for our ancestors. According to anthropologist Chris Stringer, “It was the beginning of the genus Homo. Stone toolmaking had already begun, but the brain was only beginning to enlarge.” If Sagittarius A* goes AGN again, we may be treated to our own amazing light show in the night sky.

 Not Every Cosmic Powerhouse Is A Black Hole

Galaxy Wars: M81 versus M82

For decades, many scientists believed that extremely bright X-ray sources, known as ultraluminous X-ray (ULX) sources, had to be caused by black holes eating stars or other matter. When the immense gravity of a black hole attracts the gas of a nearby star, that gas spirals down to form an accretion disk around the black hole.

Like water circling before it goes down the drain, the gas accelerates greatly, heating to extremely high temperatures that release bright X-ray light in every direction. The larger the feeding black hole, the more it consumes, and the brighter the light.

That was the theory. Then, in nearby galaxy M82, astronomers accidentally discovered a ULX source that pulsed, emitting a bright X-ray beam that swept past Earth every 1.37 seconds like a lighthouse beacon. The problem is, black holes don’t pulse. Pulsars pulse. 

A pulsar is a spinning neutron star (the remnant of a dying star that wasn’t big enough to become a black hole) that emits X-ray light from its magnetic poles like the lighthouse beacon just described. But the pulsar in the M82 galaxy is 100 times brighter than its mass should permit according to a physics guideline called the Eddington limit. It shouldn’t be a ULX source.

“You might think of this pulsar as the Mighty Mouse of stellar remnants,” said Fiona Harrison of the California Institute of Technology. “It has all the power of a black hole with much less mass. The pulsar appears to be eating the equivalent of a black hole diet.”

Astronomers now have to reexamine other ULX sources to see if they pulse. They can no longer assume that every ULX source, or cosmic powerhouse, is a black hole.

 More Gluttonous Than Imagined

NGC 7793

Until recently, scientists thought that the size of a black hole determined the top speed at which it could eat and produce light (the Eddington limit). Then they discovered P13, a black hole in the galaxy NGC7793, which rotates around a supergiant star while cannibalizing it. 

But P13 is gorging itself on its companion star’s gas 10 times faster than astronomers believed possible. P13 is believed to be 15 times smaller than our sun yet a million times brighter. It has the ability to devour its companion star in less than a million years, which is fast in cosmic time. This small black hole consumes matter with a weight equal to 100 billion billion hot dogs every minute.

“As hot dog–eating legend Takeru Kobayashi famously showed us, size does not always matter in the world of competitive eating, and even small black holes can eat gas at an exceptional rate,” said astronomer Dr. Roberto Soria. 

Like the M82 pulsar, P13 is an ultraluminous X-ray source that not only violates the Eddington limit—it knocks it out of the galaxy. Astronomers now realize that there may not be a strict limit on how much a black hole can eat.

Supermassive Black Holes May Be More Numerous Than We Thought

Overfed Black Holes Shut Down Galactic Star-Making

Black holes come in a variety of sizes, from primordial (which may be as small as one atom) to supermassive (with masses larger than one million suns packed into the size of a solar system). There may even be a rare extra-large size called ultramassive. 

At one time, only larger galaxies were believed to contain massive black holes. But in early 2014, astronomers revealed that over 100 small dwarf galaxies appear to have massive black holes at their centers. Compared to our Milky Way’s collection of 200–400 billion stars, a dwarf galaxy has only a few billion stars and far less mass.

Then, in September 2014, astronomers announced that they’d found a supermassive black hole in an ultracompact dwarf galaxy called M60-UCD1, the densest galaxy currently known.

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If you lived in M60-UCD1, you’d see at least one million stars in the night sky as opposed to the 4,000 stars we see from Earth with the naked eye. lthough the Milky Way’s central black hole has a mass of four million suns, it’s less than 0.01 percent of our galaxy’s total mass. By comparison, M60-UCD1′s central black hole is a monster, with a mass of 21 million suns that’s 15 percent of its galaxy’s total mass.

Based on these findings, some astronomers believe that many ultracompact dwarf galaxies may be the remains of larger galaxies that were torn apart when they collided with other galaxies. So there may be as many supermassive black holes in the centers of ultracompact dwarf galaxies as there are in larger galaxies

.Our Universe May Have Spawned From A 4-D Black Hole

Alpha Centauri A & B

One big problem with the big bang theory is that our scientifically predictable universe originates from a singularity, an infinitely dense point that doesn’t play by the same rules of physics. Physicists don’t understand singularities. They can’t explain what sparked the big bang.

Some physicists believe it’s unlikely that such a chaotic beginning would produce a universe with a largely uniform temperature. So three researchers from the Perimeter Institute have proposed a new theory that they insist is mathematically sound and testable.

They argue that our universe is the violently ejected outer material from the supernova death of a 4-D star whose inner layers collapsed into a black hole.

In our universe, a 3-D black hole has a 2-D event horizon, the boundary around the mouth of the black hole that represents the point of no return for anything that falls inside and gets trapped by gravity.

In a universe with four spatial dimensions, a 4-D black hole would have a 3-D event horizon. Our universe, the ejected material from the supernova, would form a 3-D membrane around the 3-D event horizon. That membrane’s growth is what we perceive as cosmic expansion. 

Our 3-D universe would have inherited the uniformity of the 4-D parent universe if that 4-D universe had existed for a long time. The researchers are still refining their model. If we consider their theory absurd, they argue that that’s simply because we don’t understand a 4-D universe. Our thinking is limited by a 3-D world that may represent only the tip of reality.