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  • kind of a neat piece of physics.

  • It ends up with a truly enormously, ridiculously big number.

  • But mainly I want to talk about it cause it gives me an excuse to show you this.

  • This is a composite of an optical picture.

  • So the kind of the grey bits of stars on a radio picture.

  • So the pinky stuff is what you see.

  • If you had radio eyes and the gray stuff, it's what you see with normal optical eyes.

  • And as you say, there was this kind of tight jet of material coming out and you see, so this is a whole galaxy large galaxy in the middle, and you could see the radio mission is way, way bigger, that even the whole extent of the galaxy's enormous scale.

  • What's going on here?

  • In fact, you can trace back because you can see these that lines where it's coming from.

  • It actually originates clearly near the middle of the galaxy.

  • And as we know strange things, look at the center of Galaxies and therefore it's probably even though it's on an enormous scale, it's probably somehow intimately tied to what's going on right in the middle of the Galaxy.

  • This must be a different galaxy to live in.

  • That were something this dynamics coming out of the center, like if something like that was coming at the center of our galaxy, that feels like would be a game changer.

  • It's an interesting question.

  • I'm not sure it would, unless you happen to be unlucky and getting right in the way of where these Jets are headed because it's so tightly column ated.

  • Actually, it doesn't have much impact on most of what's going on in the Galaxy.

  • It really is only if you're unlucky enough to get in the way.

  • But 11 interesting question, and the thing that we're gonna be able to answer with this synchrotron minimum energy stuff is, how important is it in the center?

  • Is this just kind of big and showy, or is there actually a lot of energy associated with a lot of energetic processes on?

  • Is it really kind of something we have to worry about in terms of how it interacts with the galaxy, the effect it might have on the galaxy?

  • We have to talk about where these over this mission comes from, what causes it on?

  • Then that will allow us to then unpack the how much energy there is packed away in these radio jets, and hence whether it's actually an important scratcher or just something that looks pretty.

  • So the process that amidst these radio waves is a process called synchrotron emission, which is where you have a magnetic field on a bunch of charged particles.

  • And when you got a magnetic field and a bunch of charged particles, the charged particles interact with the magnetic field.

  • They sort of spiral around it.

  • And because they're now not travelling in a straight line anymore, that means they're being accelerated.

  • And whenever you take a charged particle and accelerate, it emits radiation.

  • And in this particular case, it's the energies of the particles that sexy little omit that radiation in the radio part of the spectrum.

  • So the physical process that's leading to this mission is just basically got the magnetic fields.

  • Associating somehow with the structures and charged particle was in the combination of the two.

  • The charged particles traveling around orbiting around the magnetic field lines, then produced this synchrotron emission.

  • In this particular case, what's the source of magnetic field?

  • And what's the source of charged particles.

  • So almost certainly both you can trace back again, just following the line back to the middle.

  • It's something to do that what's going on in the middle here on whatever it is, is tangling up magnetic field lines, which will create stronger and stronger magnetic fields.

  • But also producing these particles, which then get accelerated out on the synchrotron, just means the reason they're.

  • So there's another kind of radio emission you get from electrons travelling of magnetic fields called cyclotron.

  • The difference between synchrotron cyclotron is it's called synchrotron when the electrons are traveling at relativistic speeds.

  • So we know these electrons are being shot along at incredibly high speeds.

  • I'm producing these radio emission because of that.

  • Initially you were saying charged particles.

  • Now you're saying electrons.

  • They are electrons.

  • I mean, they have to be protons as well, because you can't have.

  • You have to have a kind of charge balance in this process of protons being shot along as well.

  • But the electrons are the one that gave their presence away by producing the strong radio waves that we see fundamentally.

  • We don't know why you see this phenomenon in some Galaxies in other Galaxies, you tend to see these kind of big radio jets.

  • Where is a big elliptical galaxy, for example?

  • But no.

  • All large elliptical Galaxies produced these radio jets, so there's something that makes some Galaxies produce them and others know, or that maybe all Galaxies do it.

  • But they just switch on a switch.

  • Often, we kept some in the ANC, but so it was obviously a very strong magnetic field far away from this galaxy.

  • Actually, it turns out it's not strong at all.

  • It's actually a very weak magnetic field, but it's very, very large.

  • That's the thing.

  • There's a lot of magnetic field there, but actually, the fuel strength at any given place is actually quite small.

  • So it turns out when you calculate it, it's actually a very tiny magnetic field.

  • What would be creating around So the whole of space is permeated with magnetic fields.

  • It's kind of primordial magnetic field out there in space, and presumably what's happening here is that some processes sort of concentrating that many fields are making it stronger.

  • It's still very weak, but actually stronger than it used to be.

  • Some again, something to do with the black hole in the middle, pulling materially and strength, pulling the magnetic field lines in and creating a stronger magnetic field.

  • Now we have to get to the crux of the matter is, Does it matter?

  • Is it just all for show, or is there actually much energy associated with this?

  • And so we have to worry about it on Astrophysical scale on this takes us back to the 19 fifties, when this was first figured out by a guy called Jeffrey Burbage, who came up with a very elegant way of showing quite how much energy that has to be associated with these jets.

  • We know there are relativistic particles in the Jets, and that's clearly this energy associated with the relativistic particles, because that's kind of the kinetic energy of the particles themselves.

  • And we sought have some handle on how much energy that actually is because we can see how much radio mission there is.

  • Obviously, the Maur rapidly moving particles there are the more radio emission will see.

  • So the maths goes.

  • Something like Luminosity, you see, is proportional to the energy stored in the electrons, times the magnetic field strengths to the rearmed power.

  • It turns out this is just basically saying that the way that the you get stronger luminosity coming out, if even more high energy particles, or if that's more magnetic field.

  • So we could rearrange this because we can measure the luminosity, anything we want to know.

  • How much energy is that stored in there?

  • We could rearrange this to say that Thean gee restore is proportional to that luminosity.

  • There's over B to the three hours power.

  • That means that we measure the luminosity, and so we want to know what this energy stored in the electrons is.

  • But unfortunately, you know what the man in the field is, We can guess, but we don't actually know what it is, but we can say, OK, so we don't actually know what it is.

  • But we could plot how much energy there is stored if we just allow that made it feel to change, Okay?

  • And so I was like mine.

  • It feel goes up, the energy stored goes down, but that's in the denominator.

  • So it's going to do something like but and we know we're somewhere on that curve.

  • We don't know what the magnetic field is but we know, you know, if the magnetic field with this value, then that would be what the energy was thought.

  • But it turns out that's not the only source of energy in the Jets, because there's also energy stored in the magnetic fields themselves.

  • Have you ever taken two magnets and tried to push their poles together?

  • You know that they push each other apart.

  • Actually, when you push them together, you've stored some energy, so the stronger you make a magnetic field.

  • The Maur energy there is actually stored in the man in that field itself.

  • So it's a second term.

  • We need to worry about energy stored in the magnetic field, and it turns out of that's proportional to the magnitude field squared as you crank up the magnetic field.

  • That's amore amore energy stored in the magnetic field.

  • Similar as you push two minutes closer, close together.

  • There's more and more energy store because you've got stronger and stronger magnetic field.

  • So if we were to plot this contribution, that one goes the other way right, there actually isn't be increases that made it if the energy stored on a magnetic field goes up, so it's gonna do something like that.

  • Of course, the total energy is just that some of these two terms, it's the sum of the energy stored in the electrons that relativistic particles, which goes down with magnetic field and the energy stored in the magnetic field itself, which goes up to the minute field on the total energy is just to some of the two, which is gonna do something like that when we had the two together.

  • So again, we still don't know what the answer is because actually, we don't know what the magnetic field is still, and we just know that tells us that the total energy lies somewhere along that line way.

  • Have a minimum indeed.

  • So we know that the energy has to be stalked the store.

  • Then there has to be at least that much.

  • We know that there's some minimum energy stores when you go through the calculations, which is what Burbage first did in the 19 fifties.

  • It turns out the amount of energy is a ridiculously huge amount of energy.

  • I mean, this is a galaxy.

  • Almost everything's okay.

  • This even by galaxy standards, this is huge.

  • So the amount of energy you typically get for a galaxy like this system like this.

  • It works out that the energy stored in these radio jets of the minimum energy, remember girl was more than that is about 10 to the 52 jewels.

  • That's one with 52 zeros after it, Jules.

  • And again you write every numbers begin astronomy.

  • So let's put that in a little bit of perspective.

  • The sun gives out quite a lot of energy and one of the things that people will think about in terms of very advanced civilizations.

  • This his idea of these things called Dyson spheres.

  • What, You could actually take away the energy of the sun and use it, bend it to your will, do what you want with it.

  • So if we were to build a Dyson sphere around the sun and in fact, if we were to build a Dyson sphere around every star in the Milky Way, then if we wanted to get that much energy, the amount of energy stored in these radios would have to take away the energy from a ll the stars in the Milky Way for hundreds of millions of years and that really use a beauty, Chrisley, large amount of energy, and it tells you immediately that actually, this is a very energetic process that's going on in.

  • These jets were always told energy can't be created or destroyed.

  • Yeah, like this energy that's living in this lobes, which is lying our minds didn't just, like, come from nowhere.

  • It started some rose.

  • Where did it come from?

  • So they said, Well, there's the clue right that you could see where the Jets come from.

  • They come from right in the middle of the galaxy, and we know at the center of every galaxy that's a supermassive black hole.

  • And we know that one of the most efficient ways the res of liberating energy is the drop things into a black hole.

  • You remember that if you got some mass M, the total amount of energy associating with it is violence.

  • Stein's famous equation E M.

  • C.

  • Squared.

  • It turns out you actually, if you drop something of mass came into a black hole, you liberate some large fraction of M C squared in the process, so it's an immensely efficient way off liberating energy.

  • And if you were to power these radio lobes by dropping matter into the black hole in the middle, it works out.

  • You'd have to drop about 100,000 times the mass of the sun into that black hole, which is sounds like a big number, but actually, the black hole's probably several 100 million.

  • Solar masses in size actually is a small fraction of the total mass of that black hole.

  • But by feeding the black hole in the middle, you can generate these huge amounts of energy you need to create these radio.

  • If you'd like to see even Maur about synchrotron radiation in particular, how it's used by scientists here on Earth.

  • Well, I've made a lot of really hurts about that.

  • You can check them out.

  • I put links on the screen and in the video description.

  • And if just huge objects in space like this galaxy fascinate you, you really need to be checking out Deep Sky Videos, which is our dedicated astronomy channel.

  • And each video is about a different galaxy or cluster of stars telling you amazing things about them.

  • It's really worth checking out again.

  • Links on the screen and the description also a reminder.

kind of a neat piece of physics.

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銀河輻射(一個 "巨大得令人髮指 "的能量)--60個符號。 (Galaxy Radiation (A "Ridiculously Huge" Amount of Energy) - Sixty Symbols)

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    林宜悉 發佈於 2021 年 01 月 14 日
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