Scary Barbie - Den hitills största explosionen och den ljusaste händelsen

Scary Barbie (skumt namn jag vet men Anton Petrov förklarar varför i länken nedan) är den hittills största explosionen och den ljusstarkaste händelsen som observerats i vårt universum. Det som ytterligare gör den unik är att den pågått över tre år.

Forskare är oeniga i vad som ligger bakom och det är unikt då det troliga svarta hålet inte ligger i en verifierad galax. Detta kan bero på att händelsen är för ljusstark för att kunna observera en galax men man vet inte.

Vad tror ni ligger bakom? Är det ett svart hål på "rymmen" efter en tidigare galaktisk kollision eller finns det en galax där? Är det en stjärna som kommit för nära och slitits sönder i ett TDE "tidal disruption event" eller är det stora gasmoln som har kommit för nära eller kan det vara något helt annat?

Är det bara jag som finner detta otroligt spännande och intressant?

Vilket som så kommer jag följa detta framåt för att se vad man kommer fram till då detta i skrivande stund är en unik observation.

https://eu.usatoday.com/story/news/n...e/70212322007/
'Terrifying': Why the universe's largest cosmic explosion is called 'Scary Barbie'
MIKE SNIDER USA TODAY
They call it "Scary Barbie." But it's not a new toy, it's a cosmic event astronomers agree is the largest explosion and brightest event ever witnessed in the universe.

But two teams of researchers have arrived at different explanations for the explosion, the brilliance of which has lasted for more than three years.

https://www.youtube.com/watch?v=QlnAMEWRIyw
No Theory Can Explain Terrifying Cosmic Explosion Called Scary Barbie -Anton Petrov

Om man ska tro på dem som räknat på detta enligt videon skulle det räcka med att ett svart hål som är tio gånger större än det i Vintergatans centrum (inte omöjligt) svalde en stjärna med massa 14 gånger Solens (inte heller ovanligt).

Att det inte syns någon galax beror sannolikt på att händelsen (vars strålning är mycket starkare än från en hel galax) ägde rum så långt borta. Förhoppningsvis kan Webbteleskopet skapa klarhet kring detta.

Det som är mysko är dock att strålningen pågått i hela 800 dagar och ännu inte börjat trappa av. Det är i längsta laget för att bero på ett svart hål som sväljer en stjärna.

Kan för övrigt rekommendera Anton Petrovs andra videor för den som är intresserad av astronomi. De är ofta bra och up-to-date även om hans engelska inte är perfekt.

En GRB (Gamma Ray Burst) som är på väg rakt mot oss tro? Därav tappar den inte ljusstyrka.

Det skulle ju kunna bli lite jobbigt. Den skulle väl i såfall i princip ha samma hastighet som det ljus vi nu observerar? Även om det är 8 miljarder år sedan så borde det inte vara för långt mellan observerbart ljus och att gammastrålningen kommer fram?

Jag tror snarare på att det är ett svart hål som svalt en stjärna.

Sen kan jag bara hålla med Regulus i rekommendationen av Anton Petrovs kanal.

Imagine, for a second, a massive star that happens to be travelling *directly* into the path of a massive black hole. Not all of them can come in at the perfect angle to make a disc.
By the time the star mass is closing into the black hole, it would be going close to the speed of light.

What would be the effects of that? Everyone is talking about the accretion disk, but what if you bypass that -- a silent swallow?

So is there an angle where you get that maximum effect from a diving star before it enters the event horizon, or is that a too simplistic view of this?

The probability of getting a perfect hit is miniscule, just as in snooker. Moreover, the black hole will always have an angular momentum inherited from whatever fell into it previously. There will likely be a spinning accretion disk already in place, particularly for a supermassive black hole of the type we are discussing here that has already swallowed millions or billions of stars.

A good picture of what a black hole might actually look like is found in the movie Interstellar, where they had some astrophysicists as consultants.

That being said, a perfect hit on a non-spinning supermassive black hole would probably just make the star disappear from view. Not by crossing the horizon - this is something an outside observer will never see - but by a progressive gravitational redshift that becomes stronger the closer the star gets to the horizon.

For a normal sized black hole the star would get torn apart by tidal forces before it crosses the event horizon, but for a supermassive black hole the horizon will be far out, long before you would see this happen.

Yet, it would happen somewhere in the universe and we're looking for explanations of rare events, are we not?


Heh, ok. I know said consultants left before the action on the "planet" and the rest of the stuff. But granted - we don't know. Any planet with that much "time disruption" due to this time dilation wouldn't be able to be landed on.


That is a common misconception, as far as I know. If that was true, every black hole we see, would have everything that was ever trapped forever spinning around it. Think it through.

Perhaps, but in any case it would not explain the insane level of radiation if the star just disappears from view. You would still need an accretion disk outside the event horizon for that.


I was referring to the image of the black hole itself and its accretion disk towards the end of the movie. The humongous tidal wave etc. is of course science fiction. But good science finction.


"Forever" is a tricky concept since it just like "now" depends on your frame of reference.

Note that I spoke about what an external observer will see. And that is a star creeping ever closer to the event horizon, before it gets redshifted out of view. What actually happens "now" and where the star is "now" is a more complicated question.

In special relativity, "now" can mean different things to different observers. Your "now" can be my past and somebody else's future. It all depends on our relative velocities. But at least you can define a global "now" for a given observer, so it makes sense to ask where the star is "now", according to you.

In general relativity - which we have to consider in the case of black holes - it gets worse since your "now" is only locally defined. By that, I mean that your local "now" can be extended in different ways, depending on how you choose to slice up spacetime.

You can find a good discussion of this here:

https://physics.stackexchange.com/qu.../146852#146852

Note in particular Figure 2 (a so called Penrose diagram) where the red and blue curves represent different possible extensions of "now" for the same observer at a given local time (E).

So does it matter if the content has fallen into the black hole according to some definition of "now" or if it is stuck on the event horizon? The answer is no. All an external observer can detect is a very strong gravitational field, and that will look pretty much the same in both cases.

No. Just no. If everything that ever falls down into a black hole stays on the event horizon - they would still have the same mass, they would still have the same time dilation, but the physics around it have to be adjusted. No more singularity. Well, *cough*, the initial one that caused it?

Because no other matter would ever fall down. So these ultra-large ones - are just the same tittytiny ones, with a huge shell?

How would *that* influence the math around this?

Because it would mean that every black hole there is has a defined (minimum) mass. The rest is just the gunk stucked on the horizon.

Right?

The "gunk stuck on the horizon" (from a distant observer's point of view, nota bene) is added to the mass of the black hole. What defines a black hole is a gravitational field strong enough to create an event horizon, but the mass that contributes to this field does not have to be inside the horizon.

Imagine that Earth is a hollow shell with high density so that the total mass is the same. What would happen if you dug a hole through the shell and jumped into it? Would you stop falling once you passed the shell? No, that's not how gravity works. You would continue to fall until you reached the bottom of the gravity well, which is located at the empty center of Hollow Earth.

Now imagine that Hollow Earth is made of neutronium and its total mass is several times greater than the mass of the Sun. In that case, a black hole with an event horizon might form inside, and the shell would start to collapse towards it, but never reach it as seen by an external observer.

In fact, this is pretty much what happens during the creation of a black hole. Most of the collapsing star gets stuck "forever" on the event horizon (again, as seen by an external observer). Robert Oppenheimer called this phenomenon a "frozen star".

To somebody falling into the black hole (a so-called co-moving frame of reference) things of course would look very different. That poor person would quickly pass the event horizon and then get squeezed into the singularity.

In any case, the event horizon will expand as more matter falls into the black hole (or gets stuck on the horizon depending on who is observing it) so there is no contradiction here.

You've disproved the singularity.

Apart from that, most of what you wrote was what I was alluding to. Nothing ever passes the event horizon and remember - you are not allowed to use eternity, since black holes have a starting time. Nothing that is eternal is allowed to have a starting time.

Explain that.

Eh, no. The singularity is certainly there. What I am saying is that the formation of a black hole does not require that all of the matter ends up in the singularity, as seen by an external observer. Some or even most of it can get stuck on the event horizon, but you would still have a singularity inside.

At least, that is what the theory predicts. I am adding this caveat since we cannot observe either the event horizon or the singularity from outside.


I think you are confusing eternity with "forever". A process can certainly start at a given time and then go on forever.

That being said, black holes do not actually liver forever. That is why I used quotation marks around "forever". Eventually, they will start to evaporate due to Hawking radiation, and the event horizon will start to shrink. The smaller the hole gets, the hotter it gets and the faster it evaporates, so it will end in an flash of radiation.

However, for this to happen, the universe must first cool so that its temperature is lower than that of the black hole. The current temperature of the universe (the cosmic background radiation) is around 2.7 K. This may seem pretty cool to us, but it is actually many orders of magnitude above the temperature of a stellar-sized black hole. Only black holes with a mass smaller than the Moon could evaporate in our current universe. More massive black holes will not evaporate for a very long time, eons after all stars have burnt out.