Black hole surprises
What are black holes?
Black holes are formed when a star dies. But it must be a heavy star, 5-10 times heavier than our own star – the sun. Such a big star like this explodes when the nuclear energy source runs out. Half of it explodes outwards. The other half implodes and compressing gravity forces are so strong that it crushes the star’s atoms into infinitely dense matter – no more protons or neutrons or electrons. This is called a singularity by physicists.
Second, the gravity is so strong that particles or energy such as light cannot escape from the black hole and are trapped below a certain radius called the event horizon. Light can’t escape, and that’s why the star appears black. If another star or patch of interstellar gas passes too close, it can be sucked into the black hole in a long-tail swirling motion (Figure 2). Before it gets sucked all the way in it can emit light and can be seen by telescopes like the Hubble or the James Webb.
Third, a black hole can slowly extinguish itself. Or it can grow by accretion if it rips apart another star or by colliding and merging with another black hole.
So a black hole can be just the remnant of a single star, or it can be a massive monster that has devoured many other stars or black holes. An enormous black hole exists at the heart of our own galaxy, the Milky Way, and it’s as big as 6 million of our suns. Supermassive black holes lie at the center of virtually all large galaxies.
New discoveries are being made all the time about black holes. Here are a few from last year – 2022. The following words were adapted from an article called “15 times black holes surprised us in 2022”, by Charles Q. Choi.
Fastest growing black hole.
Astronomers have detected the fastest-growing black hole ever seen, devouring the equivalent of one Earth per second… or 95 sun masses per year. The behemoth currently has a mass 3 billion times that of the sun, making it 500 times bigger than the supermassive black hole at the heart of the Milky Way…
The rush of matter onto the surface of the black hole has resulted in a quasar — an extraordinarily bright heart of a galaxy — blasting out enough energy to make it 7,000 times brighter than the light from every star in the Milky Way. This quasar is one of the most luminous ones known…
“Now, we want to know why this one is different — did something catastrophic happen?” lead researcher Christopher Onken, a researcher at … the Australian National University (ANU), said. “Perhaps two big galaxies crashed into each other, funneling a whole lot of material onto the black hole to feed it.”
Black hole blasts leftovers at earth.
In November, 2022, astronomers found the most remote known example yet of a black hole tearing a star apart, all because of a jet of stellar “leftovers” it blasted directly at Earth (Figure 3).
This event occurred about 8.5 billion light-years away… The researchers estimated the black hole was eating about half the sun’s mass per year…
Tidal disruption events (TDEs) occur when stars wander too close to black holes. The black hole tears apart the star with incredibly powerful tidal forces created by its gravitational influence.
In about 1% of these instances of violent destruction, the black hole blasts out jets of plasma and radiation from its poles. This radiation, light, X-rays, and gamma rays, was observed by 20 other detectors at earth.
The event was 100 times brighter than any other event ever seen in gamma rays. The TDE jet must have been aimed almost directly at earth.
“We have only seen a handful of these jetted-TDEs and they remain very exotic and poorly understood events,” Nial Tanvir, an astronomer at the University of Leicester in the U.K.
Post-script: I worked in Los Alamos Scientific Laboratory in 1972, and was there when gamma ray bursts were discovered. They were found by detectors on spacecraft that were sent up into orbit to monitor potential nuclear bomb blasts by the Russians. Other detectors on the same spacecraft were able to detect cosmic rays (protons and electrons) emitted by the sun, and I spent one full year and a few summers later trying to decipher how these particles traveled from the sun to the earth.
How many black holes in the universe?
By analyzing the evolution of stars in the universe, researchers estimated how often the stars, either on their own or paired into binary systems, would transform into stellar-mass black holes — those with masses 5 to 10 times that of the sun.
Their answer: 40 quintillion black holes each about the mass of a star that altogether make up 1% of the universe’s normal matter, astronomers announced in January. That’s 40,000,000,000,000,000,000.
Since black holes are just 1% of stars, the total number of stars in the universe is 100 times this amount.
While this number is very hard to comprehend, it does show that the universe is gargantuan. The total number of stars, not just black holes, is about 10,000 times more than the number of sand grains in the whole earth.
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The Gray Nomad ….. This is truly mind-blowing information – I cant get my mind around an infinitely dense blob of material that actually exists.
I will bless you richly and I will give you countless descendants, as many as the stars in the sky and as the grains of sand on the seashore. They will conquer their enemies’ cities. [Genesis, Chapter 22].