Spinning Black Holes

Spinning Black Holes

On November 22, 2014 a burst of x-rays was detected by ASASSN that’s the All Sky Automated Survey for Super Novae but this was no supernova the signal came from the center of a galaxy around 290 million light-years away and what we now belive happened was a star came too close to a supermassive black hole with a mass millions of times that of our Sun and it was eaten The black hole fed on the star and yes, this is the actual termenology astrophysicists use to describe it Events like these are thought to be rare occurring maybe once every 10,000 to 100,000 years in a galaxy they’re called Tidal Disruption Events, or Tidal Disruption Flares as the star approached the side closest to the black hole experienced a much gravitational pull than the other side, ripping the star to shreds matter spiraling into the black hole formed an accretion disk an annular ring of gas and dust that’s accelerating and heating up emitting visible light UV and X-rays observable from Earth Now what’s remarkable about this event is that it transformed a dormant or quiescent black hole one that wasn’t really feeding into one that we can observe thanks to the matter falling in from that star and is what it looked like Okay if you’re disappointed, check out these artists renditions of the same event but if you’re cynical you might say “Well how do we know that’s what really happened? what if the scientists are just making this up to get more grant funding or to inspire people to go into science” well I’ll explain how we know this is actually what went down but first things got wierder scientists trained three X-ray telescopes to observe this part of the sky for years after the event and what they found was a strong and regular pulse of X-rays brightening and dimming every 131 seconds and it shows up in the data from all three telescopes they observed periodically over 450 days but the pulse maintained this rhythm and didn’t get weaker in fact as time went on the relative strength of the pulse got stronger modulating the X-ray signal by around 40% and what was causing these periodic flashes of X-rays and what could it tell us about the black hole well let’s back up because black holes are some of the simplest objects in the Universe by that I just mean that they are characterized by only two attributes Mass and Spin Okay, there’s also charge but since black holes should essentially be neutral mass and spin are the two that count mass is relatively easy to determine far away from a black hole, you can even use Newtonian physics. By measuring the gravitational effects of the black hole on other bodies, you can estimate the mass of of the black hole this has been done and black holes been found with masses ranging from just few times our Sun, stellar-mass black holes, up to billions of solar masses — supermassive black holes it’s generally accepted that there is a supermassive black hole at the centers of most galaxies, including our own. But what about spin? since black holes form from collapsing stars and all known starts rotate, all black holes should also be rotating I mean, what are the chances that a bunch of matter just collapses into a point perfectly with no rotation? It’s just not going to happen. And then additional matter falling into the black hole contributes its angular momentum. So like a figure skater pulling their arms into a… point object, You can imagine black holes get spinning pretty fast. But spin is harder to measure because unlike mass, it only affects objects relatively close to the black hole. But there is a way to do it. Actually, 3 ways. To understand all of them, you have to understand isco. In Newtonian physics, around a compact mass, you can place an object in a circular object at any radius and it will be stable. It doesn’t matter how close you get. This is not the case according to general relativity. Here, there is an innermost stable circular orbit, With a radius know as r-isco. Closer than this, and no orbits are stable: they all fall into the black hole. So when you’re looking at a black hole that is feeding, the innermost edge of the accretion disk is at r-isco. What’s useful for our purposes is that r-isco depends on the spin of the black hole. The faster it’s spinning, the smaller r-isco becomes. Assuming it’s spinning in the same direction as the matter in the accretion disk. The rotation enables particles to orbit closer to the black hole, than they’d be able to for a non-spinning black hole. So you can kind of think of it as though the spin is supporting the particles against the relentless pull of gravity. Now spin is normally discussed in terms of a dimensionless parameter that ranges from 0, no spin, to 1, maximum spin. Though I guess you could also have spins down to -1 if the black hole is spinning in the opposite direction from the accretion disk. Now, as spin increases, r-isco decreases. by a factor of 6, shrinking down to the size of the event horizon. And this sets what many scientists think is the maximum spin a black hole can have. Because if the minimum stable orbit were the size of the event horizon, Then light could escape from the black hole, allowing us to see into the singularity. This is called a naked singularity, and it makes a lot of scientists uncomfortable. As yet, there isn’t a strong theoretical reason why a black hole can’t exceed this maximum spin, It’s just that we haven’t seen one, and the thought of an exposed singularity just kind of… feels wrong. Most suspect the maximum real-world spin parameter is around 0.998. So how can you use r-isco to measure the spin of a black hole? Well first, let’s think of how we measure the size of anything far away from us in deep space, like the radius of a star Most stars are so far away that they’re simply point objects in our telescopes. So how can you figure out their radii? Well, first, look at the spectrum of their light. By seeing how red-shifted absorption lines are, you can determine how far away the star is. The spectrum also tells you the temperature of the star — Because it should approximate a black-body curve. And now the power radiated per unit area is strongly dependent on its temperature. So if you know how bright the star appears from Earth, how far away it is, and how much power its radiating per unit area, Well, then you could work out its area and hence its radius. You can actually so something very similar for a black hole’s accretion disk. Just instead of estimating the radius of a glowing sphere, you’re estimating the radius of the dark circle, r-isco, in the middle of the glowing accretion disk. Then you can use r-isco to find the spin parameter. This has been done for a number of black holes, revealing spin parameters from around 0.1 up to close to the maximum. But this method only works if the radiation from the black hole is dominated by black-body radiation from the accretion disk. which, often, it’s not. Another approach involves looking at x-rays emitted by iron around a black hole. Some black holes show a distinct iron emission line. But instead of the single frequency you’d expect, the line is broadened by factors like the Doppler shift due to the high velocity of the iron in the accretion disk. and gravitational redshift, due to the extreme gravitational fields close to the black hole. By looking at the low-energy limit of the iron emission line, you can determine how close the black hole it was emitted. And hence, r-isco. But what if there is no bright iron emission line? Well, luckily, there is a third way. And that, is to look for periodic oscillations in the data. Like the repeated x-rays observed every 131 seconds. The thinking is, these cycles must be caused by clumps of matter orbiting the black hole. And at frequencies that high, they must be orbiting very close in, probably near r-isco. Even that close, they’d be going half the speed of light. But what kind of clumps or objects would these be? Well the study’s authors argue that the best candidate involves an unlikely scenario: Years before the tidal disruption event, they propose that there was a white dwarf start in orbit around this black hole. Now, it might be stable, orbiting in this way, for perhaps one or two hundred years. By itself it wouldn’t be visible from Earth. But then the other star wondered by, and was ripped apart in the tidal disruption event. Its mass fell in towards the black hole forming an accretion disk. With the addition of this stellar debris, the white dwarf was cloaked in glowing matter, creating an x-ray hotspot orbiting the black hole, and its period would directly relate to the spin of the black hole. In this case, the measured spin parameter turned out to be at least 0.7 and possibly as high as the theoretical maximum of 0.998, meaning objects in the accretion disk were going at least half the speed of light. This is the first measurement of spin made possible by a tidal disruption event. The implication is that this could provide a method for determining the spin of black holes. Particularly ones that have been dormant, which is about 95% of supermassive black holes. If they shred a star, we get insight into their spin. Now why is this important? Well, because it helps us understand the origins of black holes. If supermassive black holes grow in size mainly by feeding on a steady stream of matter from within their own galaxy, You’d expect their spins to be very large, because the angular momentum of that matter would be more or less aligned. so it would add up over time. But if instead, supermassive black holes grow predominantly by merging with other black holes, You might expect their spins to be lower, because the spins of two black holes are likely to be randomly oriented rather than aligned. As we are able to measure the spins of more black holes in different ways, farther out and therefore further back in time, We should be able to better understand their growth. And since supermassive black holes lie at the center of most galaxies, They also lie at the center of an understanding of how those galaxies have formed and evolved over billions of years.

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  1. Why is r-isco not the event horizon?

    Also, does the Earth have an r-isco (satellites orbiting too close get pulled in by gravity/atmosphere)? If so, we could tell Newtonian physics is wrong simply from objects orbiting too close to planets

  2. If the gravitational force of a black hole is so great that light can't escape, I wonder what the inside of one looks like.

  3. 3:16 – Oh so its not possible for matter to collapse perfectly and create a black hole without spin, but its possible for a "big bang" to line things up perfectly to form humans – extremely complicated organism…This is just outrageous and I call bs

  4. So black holes eat stars and that’s how galaxies are born…. looks like you guys kinda got this whole thing figured out. Pack up, the day is over.

  5. How much you wanna bet a black hole is dark matter and that black hole have you guys seen a white hole it's amazing

  6. 0:34
    I think it is not rare.
    Only for us with the limited sight.
    Our technology is not good enough to scan the whole univers at the same time.

  7. if dwarf star is rotating around black hole then intensity of light by the star should varying due to bending of light?

  8. I don't believe space is expanding.. or dark matter. Think about a firework going off or an explosion. The Big Bang was just an explosion and all matter is still moving in the direction it went to this day with almost nothing in space to stop it. When black holes get large.. so does their magnetic field. Eventually this magnetic field will encompass other stars and black holes and they will merge until there is one single black hole with all the matter in the universe. (Singularity).. Then it explodes again and does the same thing over and over for all of time.

  9. Wow, if there will be any possibility to this white dwarf to get free from gravitation of black hole, it would be a so deadly bullet… Just imagine a star core, that moves in space with 0.5 speed of light. It will rip a starts like a butter and just go forward.

  10. That "White" dwarf is about the size of Earths moon but weights a million times more than our Sun. According to this video, this dwarf is spinning around the black hole at half the speed of light😮😮😮😧

  11. 3:46 for Indian " you have to understand isko " mean " your have to understand this " isko ( इसको ) = This !! 😋

  12. 6:01 but i learned before that , redshift only tell how fast star moving away from us ! So what your mean ??

  13. you're going to explain how we "know" a spinning black hole ate a star? you're supposed to be veritasium … many elements of TRUTH! You're repeating a bunch of theory which is unproven. Does the math work? yes, according to those (who understand) the math. Does that mean we should call it truth? No, it's theory. … it's not just one theory, it's a stack of theory. for example, when "these scientists" discover a black hole (by an instrument with way too much signal to noise) which shouldn't exist… they scratch their heads and Make up sh1t (like e.g. Dark Matter) to explain how their stack of theories can be created! Wow, this isn't science. Science is a theory/model which Can be Falsified by Experiments… Anybody doing experiments to Falsify Black Hole theory???? Nope! they, like you, are all bought in! too stupid! … oh the other star wandered by making the black hole light up which is Why the black holes aren't dark… wow, too stupid! :-p

  14. A naked singularity… BWAHAHAHAHAHAHAHA if a black hole was spinning fast enough to become naked it would be shooting out omg particles and gamma rays like mad, And it would be rather rare. Coughs, Thats what i would consider to be hawking radiation, Perhaps its a spin state.

  15. Oye…. you speak waaay to fast for me…. Me is a mortal my frend….. no understand astrofisics easy…. No, seriously, I know Americans have lead us to watch a lot faster movies and videos over the decades for some reason, but this is astrophysics man! please have mercy on us and try and explain as if we were some 6 year olds okay? Ok, I have some questions….. 1. If it is a black HOLE, why does it have a mass???? I mean, I know the outer "space" is no such a thing, it´s rather like a tissue of space-time…. that I understand…. But talking about black holes, Why? Why is there a mass in something that we call a "hole"? I mean, what is this mass made off? black matter?2… wait…. let me watch again…

  16. 2. R ISCO decreases by a factor of 6? 6 what? Where did that number come from? 3. They think a maximum spin in a black hole is equal to its event horizon? Can you please explain?

  17. Thank You for a great video, big fan of this channel. I do have a question though and I apologize for potential ridiculousness of it as astro-physics or or really any physics is very far from being my daily subjects of involvement but are much of personal curiosity. So if the massive star that got eaten by the black hole actually got consumed while passing by the black hole then wouldn't it's trajectory have to intersect with the actual event horizon of the black hole in order to be effected or is the animation just not correct? Also wouldn't the mass of the star that got eaten have to be smaller than that or the dwarf star that is apparently circling the black hole emitting those x-rays in order to experience effect of the gravity since the dwarf star manages to circle around without the experience of the same effect? and lastly how come there is any light or debris left circling the black hole? by my logic if the large massive start got engulfed while passing by then there really shouldn't be anything left from it and only hawking radiation would get emitted according to some earlier videos from this channel. Greatly appreciate any potential relative responses 🙂

  18. So if a small black hole (newly formed out of a collapsing sun) spins faster than a bigger one, isn´t thar just an indicator that we haven´t really reached a singularity on the inside of the black hole, because there is still stuff spinning around. Thus less spin should be an indicator for a "denser" black hole coming closer to a true singularity, while the shape tha we see becomes larger. This would provoce the question: Should something truely being infinite dense (so a singularity) should be not be spinning at all and be infintly large at the same time consuming everything/ the whole universe?
    Like relativly speaking.. the more it consumes and denser it becomes, it appears bigger because it has just consumed more mass.
    Like if you would blow up a ballon, fill it up with a little but of something floating around (e.g. dust) and let that represent suff floating around in our universe.
    Poke a hole in the ballon and stuff will be blown out. But if you were on the inside living on the "dust" it would appear as stuff was sucked in that hole. Stuff would be even spinning and twerling around that hole. But the hole wouldn´t really become bigger but seen from the inside it has sucked up so much of your observable space it relativly appears larger from your point of view. At the same time the more stuff it has sucked out the less stuff is of course on the inside and twerling around that hole. Until the point there is nothing more left in that ballon and it's totally empty ( a state you can't really achive with a ballon). At this point the hole would make up the whole abservable space as well as kinda not excisting at all.

  19. So is a Galaxy not just a giant accretion disk? Just instead of near by gravity affect, it attracted further and further out, allowing the close objects to attract some further away and so on till a galaxy is formed?

  20. Just want to have a cool conversation about the coolest topic of science right now… SPACE TRAVEL… but I'm not a Scientist…

    Have you guys considered that the negative energy needed in the warp drive could be the same energy that civilizations 3 tier from the KARDASHEV Scale would harvest from black holes? since planets and stars have mass and mass creates Positive Energy + Time and Gravity in the Plain Field right?
    the accretion disc is a + in the math of the black hole with the mass of the other…

    Again, sorry, I'm no scientist, but if black holes harvest energy from the positive universe it may transform in negative energy when it goes in, but with time it may let the negative energy out if they are like wormholes right? and that's what I'm thinking what if black holes do let this energy come out and there are like billions of black holes out there and they make the expansion slowly but getting faster because of the energy they pull in making them bigger… making the process of acceleration of the universe faster because of this energy that comes back…

    And if this would be possible to happen we would need some kind of harvest machine for it… something that doesn't get pulled inside the horizon of events but it's all around it to harvest that energy that comes out of it…

  21. i thought the faster you move, the closer circle you can make, so it wouldnt have anything to do with the black hole spinning, but how fast the stuff around it is moving

  22. what if a black hole is just some sort of advanced cloaking device by a very advanced alien race and they are out harvesting stars for power.

  23. No black holes have been seen. only very fast rotations of stars. AKA plazmoid. Universe is ELECTRIC period.. VERY out dated information.. but i like you. get up with walace thornhill.. You will do a lot better!

  24. Okay so, this sounds like a dumb set of questions. Is there a range within the orbit of a black hole where life can be sustainably formed and maintained? Like a Goldilocks zone present in stellar orbits for solar systems? Is there a point where the amount of radiation is such that life can exist without being heavily impacted by said radiation?

  25. When I was young, black holes were sc-fi …. then what happened? I ment by that when did it became so real??? Few years back when we captée a quantum wave??

  26. Not even light can escape a black hole, except when it does, and stuff can just float around it. Look at this picture we took. Such fiction.

  27. I have a question about how time behaves inside a black hole, reggarding the spin. If for a distant observer time seems to go slower the closer you are to the singularity, does this mean that at the singularity there's no time for any observer outside the event horizon? If so, how can the accretion disk's r isco be affected by a spin that is not actually happening outside the zero dimensional singularity because of the infinitely slow time? In simple words, how can a singularity spin if there is no time?

  28. Note to viewers: This is all nonsense, I'm brainwashed and socially inept so I still believe in the "space" deception. I do this of course for views and to keep the satanic lies dispelling the truth alive. I am an minion and even realize there are no pics of Earth from "space" but I'm to hardened to use logic. Burn in hell!

  29. i would be interested in time scales for cosmic events, obviously animation runs at a speed that lets us see the action, real time could take weeks or be gone in a flash, but it's hard to get a grasp of cosmic events, some do take seconds, some take days and others take years, but black holes, galaxies, exploding stars, all these things are a bit hazy to me time-scale wise, stuff might be flying off a star near the speed of light, but it could still be years before a jet of gas, or a cloud of dust can be detected. i'll look, but are there any vids that talk about how long different cosmic events take? thanks.

  30. I would like to know on what timescales those events take place, like the shredding of a star by a black hole. Is it hundreds of years of millions of years? Or even just a few years?

  31. Sorry mate, been loving your videos and find your very insightful. But black holes are fiction. A theoretical result of an equation. Not observable and not provable. What is provable is that they are not possible and the maths will prove that Einstein manipulates figures and reality to serve his purpose. As a lot of mathemagicians like to do. Watch this brilliant mathematician and decide for yourself if what you thought is right, is still right. 🙂



  33. See this makes me wonder how scientists can be sure there is a maximum spin speed. Part of, or maybe all the reason as to how/why/what black holes are could be down to the speed at which they spin. The speed observed in the horizon could just be when it starts to pick up.

  34. God told us about the (black hole)night comer 1500 hundred years ago
    وَالسَّمَاءِ وَالطَّارِقِ * وَمَا أَدْرَاكَ مَا الطَّارِقُ * النَّجْمُ الثَّاقِبُ

    Oh the space & the night comer do you know what’s the night comer it’s the star the piercing with a strong gravitational field

    السماء. Oh the sky ,Space; welkin
    و الطارق night comer ; night visitor
    و ما ادراك did you realize, understand
    ما الطارق What is the night comer
    النجم The star, Origin
    الثاقب the piercing, Crevice

    (Astronomy) is a very small area of ​​space with a strong gravitational field that does not allow light to pass through

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