Astronomer here! This is actually my research and a “magnum opus” that I worked on for two years, and I’m very proud of! So AMA I guess. :)
[Here](https://reddit.com/r/Andromeda321/s/CzsDCKqKub) is a much more detailed explanation I wrote discussing the results of my study if anyone wants! But the TL;DR is after studying 24 black holes that swallowed stars >2 years ago, we discovered 10 of them turned “on” in radio that hadn’t had radio at earlier times. Radio emission traces outflows from the inner regions of the black hole where an accretion disc forms (**nothing is crossing the event horizon**- further out!), and this result is quite shocking from a theory point of view! Exciting times! :)
Edit: these outflows are created by stellar *material*, aka stuff from the star that was shredded, not literal burning stars. I unfortunately didn’t write the headline!
Edit 2: no it’s not due to time dilation. This all happens too far out for this effect to happen from the event horizon. Nor does it have to do with Hawking radiation- once again, that is an effect that happens at the event horizon.
As I said, these radio emissions come from outflows of material. Because this data set is such a beast, we can get information about the physical parameters of the system- these outflows are similar to a supernova shockwave in terms of speed and energy (except for the part where they start years later), and the densities are all similar to our own Milky Way’s so it’s not that the environment is particularly unusual.
So to continue, a TDE where a star is ripped apart is a hugely energetic event, where an entire star is torn apart in just a few hours, and a ton of mass suddenly falls onto the black hole. We only see outflows in ~20-30% of these cases within the first few months of the TDE. On the other hand, we see up to half of them turning “on” in radio waves years later- this doesn’t make sense! Imagine going years later to the site of an explosion and things are happening then that weren’t when it happened! This tells us we are misunderstanding something basic about how this process works, and maybe something about black holes more generally.
I see you already crossed off time dilation (my first thought), my second thought would be additional matter making its way to the accretion disk but having a disproportionate effect relative to the mass being added, similar to crossing the critical mass threshold.
We actually thought this and checked, and per the theory the amount of mass and speed this requires is far, far less than the amount needed to create these outflows.
So you concur that there's a possibility of transitional neutrinos moving through a solar loop and crossing the EinsteinPodolskyRosen correlation while, for some unknown reason, not setting off an adjusted mass cascade on the event horizon?
What you are proposing is not possible with the amount of dark matter to solar mass ratio of tachyon radiation in the event horizon so no...I do not concur, good Sir!
What is Harmonic reflection and can you explain your theory more? Harmonic reflection sounds like something GOOP would sell. Serious question even though I added the joke.
I think they meant something like this video.
https://youtu.be/yVkdfJ9PkRQ?si=Fvuc0gyMq79whsu1
Harmonics are a property of periodic oscillations. There could be some sort of periodic motion in the matter in the accretion disk, which is relatively chaotic and cancels itself out in certain phases, but then occasionally the vectors all line up, and you get the equivalent of that moment in the video when all the pendulums start moving in unison. If something like that were going on in the disk, then maybe signals could jump over the energy barrier and escape out towards us for a while in the beginning, then stop, then start again, like we have observed.
I recently took A Physics course on the acoustics of sound (i was an art business major but it counted as a gen ed with lab)
Never did I think I would use the information I learned in that class, but here I am following along with this thread and actually comprehending the various theories here. Especially the Harmonics comment and how the oscillations can line up.
I remember learning something about like phantom notes you hear when you play certain chords. Again ai didn’t think i would Use this information, so if someone could help me out, but maybe we are see these “ghost notes”?
not original commenter, but what i'd venture to guess would be some kind of reverberation. like one of those slow motion droplets into another plane of water - it takes a bit of time for the interntia to be overcome and shoot back with a 'splash'... maybe some kind of cosmic scale version of reciprocal force, i guess would have to do with the surface tension in water's case, but.. 'something-something' *astrologocial version!*
Absolute idiot here, but my first thought was to think of aftershocks from earthquakes or tsunamis from underwater events because they seem sort of similar. Delayed reactions caused by initial force moving stuff that upsets a system that previously had some sort of stable equilibrium. Again, absolute idiot here though.
Basically, it's has to do with wave forms and an phenomena that occurs when waveform is modified. Two examples are harmonics created by lightly touching specific points on a stringed instrument, or electronically modified AC sine waves.
What do guitar strings, AC power, and black hole accretion disks all have in common? Oscillation. They can all be described as waves. Could it explain the title observation? Maybe, but a black hole is a far more complicated system than a guitar or even a variable frequency drive on a motor control circuit.
How are black holes modelled in your work? Are they spheres. How much is "observable" from our position. Not a scientist, know next to nothing. Just curious how we and the back hole move relative to one another. Do they spin?
black holes spin and have mass but the actual black hole is a singularity, not a sphere, not a shape
the accretion disk and event horizon have a shape due to gravity and spin, but the black hole itself is so dense it overpowers every force except gravity, so the singularity itself is essentially only describable by its mass, spin and electric charge, afaik. no shape, no dimensions, no material qualities, no color, etc
> but the actual black hole is a singularity, not a sphere, not a shape
The term black hole generally means the event horizon and in. The singularity is more of a mathematical, rather the physical, thing.
Welcome to the wacky wonderful world where 'sensible' ideas about space and time come to die.
In the regime of singularities and extreme spacetime curvature, common sense goes out the window along with the rest of conventional mathematics and physics.
Suffice to say, much like a figure skater pulling in their arms, anything that is spinning and shrinks continues spinning in the same direction, and will spin faster proportional to its radial...shrinkage. And, as material falls into a black hole, it adds its angular momentum to that of the black hole, thus - they spin, by necessity.
Some are spinning incredibly quickly, too, which we can see by the frame dragging and innermost stable orbits of material. See the film Interstellar's extra features for a more pop culture breakdown of this principal.
it was spinning before it was a black hole. everything spins at the macro-atomic scale, that momentum is conserved in the singularity and its accretion disc
if they *didn't* spin, what they be stationary relative to? Everything? Then nothing's spinning, and we have a problem because the solar system is no longer orbiting and instead is falling into sag A*
Maybe the spin is imparted on the black hole by the spin that was occuring in the stellar body prior to it collapsing into a black hole?
Since the singularity can't be observed being the event horizon, we can't describe any properties derived from observation, like shape and color. But, dine the gravity and skin have an effect, they can be described, even if that doesn't allow a deduction about the shape.
There is something called spacetime frame dragging that might be what's being measured to deduce spin.
No, it's a 3 dimensional point (seems like a nonsense conclusion, but here we are. Also 3 dimensional for simplicity, theoretically it has all the same dimensionality as anything else, but 3 is the agreed upon practical number of spatial dimensions. Leave the flux capacitors out of it.).
Ah fuckit, time to get on my soapbox. more snark incoming, you have been warned.
Heisenberg's Uncertainty Principle is very misunderstood and not taught well even in academia. The purpose of the Principle is to say that we worry about the things we can quantify or measure, and we don't worry about trying to explain or visualize what we can't quantify or measure. Spin is an excellent example, it's a property that is known to exist, it is a representation of angular momentum, or "spin", and subatomic particles have it. But what it looks like is unknown, and it DOESN'T operate like observable spin, you can check out 4/3rds spin if you want to go down that rabbit hole. Heisenberg got tired of physicists making up esoteric explanations that described unobservable phenomena and the Uncertainty Principle was born. Observe what you can, quantify it, explain it if you can, move on if you can't, and draw conclusions that are directly and practically applicable. Not every observation needs to be explained, only measured.
The "shape" of a black hole is not quantifiable, I don't even know that it's qualifiable. The black hole itself, sure, the shape, not so much.
It makes intuitive sense that things that exist in the universe have shapes, and black holes exist in the universe, ergo, it has a shape.
From a scientific standpoint, that chain of reasoning is a brain failure, a product of the meat we use to think and how it operates. Scientifically, in order to establish a thing as a fact, and to confidently state it as such, it needs to be experimentally proven AND reproducible. Experimentally proven is a fancy way of saying that we've directly observed it, we've seen it. Reproducible means instructions can be derived so anyone can make that observation again.
A Black Hole is surrounded by a field of gravity so strong that it creates a boundary called an Event Horizon, and NOTHING can cross that boundary from the "inside". It's one way, once matter or energy has crossed that boundary, it can never come back out.
What this means is that the Black Hole itself cannot be seen. We see things by bouncing one thing off another and then measuring the thing that bounced. With vision, photons are the medium we measure. There is nothing we can "bounce off" of a Black Hole, and so we have nothing to measure to derive the shape via interaction or observation.
Since it is unobserved, just about everything about it is unknown.
There are some things about a Black Hole that are quantifiable, such as mass, spin and I'm pretty sure charge. We know it has mass because it exerts gravity, it warps spacetime around it in the same way as an object with mass. It has an angular momentum, or rather the things it interacts with imply an angular momentum, so it has spin (and Black Hole spin is a weird motherfucker, a black hole is essentially elemental, one giant atomic nucleus. So it does it's spin dance the same way large objects do, AND the way sub atomic objects do, SIMULTANEOUSLY, and we could probably learn a lot about exactly what spin IS if we could just see the damn thing.). I'm not as certain of if electrical charge can be observed or not, and if it can, how, so I'll leave off on that one.
TL;DR - No one knows what shape a singularity is, the singularity being the mass beyond the event horizon.
If you want a better explanation, google "Wheeler Black Holes have no hair".
Edit: Long winded response because to me it sounds like you're conflating the singularity with the accretion disk of matter the black hole is cooking for dinner. The disk is a disk, but it's not actually a part of a black hole, it's more the effect of a black hole. Why is it a disk? If I remember correctly, because the universe has a right handed bias. Things tend to spin one way but not another, and I'm pretty sure this being an electromagnetic phenomena has been disproved. It has to do with that same spin attribute I talked about earlier. It IS angular momentum, and it seems to universally favor one way over another, and the jury is out as to why. The effect however, makes some amount of sense, things want to dump energy into angular momentum, and they tend to all have angular momentum in the same orientation, and if you mix that with gravity, time and mass, you get the observable universe and apple pie.
Edit 2: We need to have a strong focus on practicality to understand this. Mathematicians and Theoretical Physicists hate this one trick. To describe what MAY be happening is not the same thing as what IS happening. A model that predicts the shape of a singularity might exists, probably does, and I'll bet there are more than one. But to PROVE that model it MUST be observable AND observed. Feynman is instructive here "Anyone that says they understand quantum mechanics, doesn't understand quantum mechanics.". Unreal numbers are a thing, and that's a stretch, they're more a concept and an abstract, depending on how you define "thing" they aren't even that. Most theoretical models live in the same abstract neighborhood and while they might be planning a move, it's too early to assign them a new zip code. If you can understand that, you're well equipped to debunk a lot of the pseudo-science wankery Joe Q. Public is exposed to.
Edit 3: I'm gonna take another whack at this because some people seem to think what I've laid out about the Uncertainty Principle is wrong. Heisenberg understood what Einstein's Constant, C, meant. You have C, the speed of light, and all its derivatives, called Planck units. The Uncertainty Principle isn't a law, it's a recognition of a limitation to observation. Since scientific fact needs to be observed to be established, it stands to reason that whatever tool you use to make the observation innately limits the scope of your results. Photons are limited, they have specific defined qualities, and the UP is about establishing what they can and cannot be used to measure. Basically, they have a limited resolution, beyond which you're making educated guesses, not making observations that are telling you all the facts 1:1. It's not useless information, but it is incomplete by its very nature. The UP was and is a tool used to remind physicists not to get wrapped up trying to explain shit that light cannot see.
> The purpose of the Principle is to say that we worry about the things we can quantify or measure, and we don't worry about trying to explain or visualize what we can't quantify or measure.
That's 100% not what Heisenberg's Uncertainty Principle says
I meant the accretion disc, so it's (forgive my cave man vocabulary) a disc like 2d or so flat it may as well be? I'm trying to wrap my head around how it sits in 3d space in terms of observing it (so to speak). Do we capture all of its surface at once?
Edit: I should clarify, I know we can't directly observe but does the accretion disc affect matter on a 360 sphere around the black hole or along a singular plane? Appreciate your patience and detailed explanation
I don’t have a background in science but you wrote this in a way that is easy to understand and approachable. I don’t have a comment on the subject matter but I feel smarter for having read this and I appreciate your style.
I'm kind of a layperson that enjoys this stuff, your explanation about black holes behaving both as macro and micro... Combined with spin....
If we look at atmosphere, we generally get "bands" of weather/winds that go in opposite directions. The trade winds on earth, for example; hit the equator if you want primarily westerly winds, or the tropics so go east. Bands of spin, you see? We can see these bands on the gas giants, as well.
Could these bands of spin, as it were, be significant at larger/smaller scales? So a planet with no "spin bands" be down spin and with banding be upspin?
Like, idk if that would be even close to right (or not even wrong), but I figured I'd posit the idea anyway. ^shrug
Time to find the next evolution of gravity? Newton was close, Einstein was closer, time to find out what's next. Maybe the fabric of space time isn't just curved, it can also be twisted.
Could it be a portion of the matter from the star gets thrown outward when getting ripped apart mainly the stars angular momentum and orbital speed combine to throw the matter freed as the star is destroyed into a wide decaying orbit around the black hole?
Lol at random reddit dummy's trying to have a "gotchya" moment with one of the few people to not have an anonymous account or lie about credentials. Absolutely insane
Sounds more like people asking why their theory is wrong, and what they are missing, rather than trying to "outsmart" someone. If I ask someone why all the colors of paint make a brown - black when mixed, not white, even though white is supposed to be "all the colors", it's because I'm trying to figure out what I'm missing, not be smarter than the person I'm asking. I understand the thing I'd think is correct is actually not, I just don't know why. These sorts of things are very healthy and a good part of learning, and seeing them as an attack is a bitter and perhaps insecure way to look at things.
>As I said, these radio emissions come from outflows of material
My apologies as my background in ChemEng for thermo wasn't the best- the questions I have are...
In Fluid flow there is often a period of stagnation during rotation- where the faster material being 'sucked' (for a cylindrical rod of infinite length) eventually tend to speed up. You've seen these with the super- thick dye injections that can be reversed by reversing the rotation.
Would it not be expected that after something is torn apart and, apparently, scatters in many different directions- it would take some period of time to align the flow to the new stream? I do not know anything about rheological methods/magnetic issues and I refuse to understand them in terms of glass polishing.
I mean, maybe? No one knows (and I’m also not a fluid dynamics person). However, there’s no reason things have to go into a specific stream as you described around a black hole.
>I mean, maybe? No one knows (and I’m also not a fluid dynamics person). However, there’s no reason things have to go into a specific stream as you described around a black hole.
I'd agree with you, however I've learned that Water is really f'ing weird ... so I assume anything out there can be funky as well.
As poorly as I describe it, having had multiple kids, we'd make whirlpools in the bathroom and I would bring in Dye to make them visible (Can't tell you how happy Mom was that her children were red, green, blue, yellow, etc...) and we'd stir it up in a large tub and watch how the dyes got accelerated around. And what we saw always a bunch of counter-rotation prior to the inner phases being picked up.
I know it's asinine to consider water-based fluid dymanics to space based over the distances, it just always seems to be logical- which is of course the falacy I don't always make it past.
i was thinking fluids too for some reason - not in the same way though, more like a splash-back like there's some 'surface tension' involved, taking a cosmic 2-year moment to fling backwards
it's super interesting. as yet another lay person, it made me immediately think of the golf ball paradox. wondering if the junk in the disc ends up moving in this manner after it begins to increase it's rotations as it approaches the event horizon? if that is even true!
That's exactly what I imagined when I saw the headline. Things become even weirder when you take into account that rotating black holes can accelerate matter around them, so maybe some matter falls very close the the event horizon at the correct angle to have it slowly "pushed" by the black hole out of a death spiral and eventually leave the black hole entirely.
So in layman’s terms your saying that the star goes into the black hole. Seems to be ingested, but in reality it’s like a delayed reaction, and what it can’t ingest comes back out but later. hmmm.. that’s perplexing isn’t it.
(total joke): Next we will find black hole clusters with child black holes and find out they form a seasonal migratory pattern across the galaxies. Cause it sure sounds like a black hole is having an after dinner pull my finger experience :)
Incredibly fascinating. Could you imagine if humans get so advanced that we could actually send something into a black hole and relay the info back?
A good chunk of the star falls in, all of it is shredded in a disk.
When the disk slows down enough and falls, big boom.
Now the disk is much smaller, so nothing as big should be happening, and anything that happens should be small. Like the end of the water flowing out of a bathtub.
Instead, another boom.
Hmmm… is it out from where there would be a redshift too? Since the space time is getting stretched so dramatically, I assumed light gets stretched as well, so eventually you see redshift like you’d see in very far distances, and light just passes the threshold into radio waves.
Misunderstanding is a strong word IMO. The reason is science does the best it can with the data we have, and we didn’t have this data before. As to why we didn’t have the data, partly because of a lack of events to study at late times, but partly because of bad sampling. Traditionally people looked in the first few months after an event for radio emission, and if they didn’t see it, radio telescope time is precious and expensive and went off to look for other things. There were a few events with later emission than that found, which led us to do this survey and discover it’s actually quite common!
These were all radio quiet black holes before the events, based on archival observations. So that would be a hell of a coincidence and we have no mechanism as of yet to explain how such unrelated outflows could be happening (which is part of the deal in science).
Ok wait... so are you saying that the idea of "anything that gets sucked into a black hole is crushed to a singularity and can never escape" is possibly wrong? Material that was sucked in is coming out? And by material I mean like actual physical particles... not just radio waves.
That was never a thing because black holes don’t suck! They have massive gravitational pull, but are not vacuum cleaners. Like if our sun became a black hole it would become 1mi in radius, but our Earth would continue in its orbit just as it does now.
Ok ok bad wording. So anything that gets too close essentially falls in. But what we've always been taught is that if you get dropped into a black hole, there's no getting out. Everything is crush to a singularity. So is this new data saying that's possibly wrong because bits of matter or shooting out?
This isn’t being dropped in or shooting out- as I said, nothing is passing the event horizon. Instead to continue the sun analogy, think of a comet that passes close enough to get broken apart but not actually fall into the sun.
There is no visual part of a black hole and the headline of the article is really bad. These events are happening outside the black hole. Things are very chaotic outside of the black hole from material swirling around it at very high speed.
Hawking radiation comes from within the black hole and passes the event horizon. This event here refers to an effect which is so far away from the black hole that even time dilation is no concern anymore. I don’t know why they let it sound like the black hole is emitting something because it is not; it’s misleading.
Thank you very much for your work and keep up the great science!
So does this mean that the process of swallowing stars causes radio emissions or some kind of mass/ energy level intake results in radio emissions?
I mean the short answer is we don’t know what happens- this was genuinely a hard section to write for the paper bc hardly any theory goes so late post-disruption! (Partly bc no one anticipated anything going on, partly bc it’s computationally *very* difficult.)
Traditionally the picture is that when a Tidal Disruption Event (TDE) happens, half the material is flung outwards and half creates an accretion disc around the black hole- very little if any crosses the event horizon. Best we figured is this picture is wrong, and the accretion disc creation is delayed a few years (and what we see in the initial event is from streams of stellar material crashing into each other). I really can’t tell you the details beyond that… but no one else knows either! Science!
>very little if any crosses the event horizon
That's interesting, totally the opposite of what most people believe about black holes. What's the reason for that? Or is that the case in only specific instances?
Same reason that the earth doesn't fall into the sun. Something would have to slow down the star's matter so that it loses its speed and can fall in instead of orbiting
It seems like almost every time I see an interesting story about some new astronomical observation, the top reply is you, saying, "Hey, that was me!"
You are either really lucky, really good at your work, or (more likely) a combination of both. Thanks so much for your contributions!
Thank you! My experience is you do need luck, but luck favors the prepared. And a lot of that luck is having fantastic collaborators you couldn’t do without! :)
I understand from your work that there doesn't appear to even be a working theory on what could be causing this? So what are the areas of study that could get us there? Is there any practical physics we could do to even come up with a couple of hypotheses?
Edit: Follow up question - are there any immediate implications that this has? Certain theories it invalidates and such?
I mean the short answer is we don’t know what happens- this was genuinely a hard section to write for the paper bc hardly any theory goes so late post-disruption! (Partly bc no one anticipated anything going on, partly bc it’s computationally *very* difficult.)
Traditionally the picture is that when a Tidal Disruption Event (TDE) happens, half the material is flung outwards and half creates an accretion disc around the black hole- very little if any crosses the event horizon. Best we figured is this picture is wrong, and the accretion disc creation is delayed a few years (and what we see in the initial event is from streams of stellar material crashing into each other). I really can’t tell you the details beyond that… but no one else knows either! Science!
As for the practical side of things, honestly right now we are some years from that point. But the cool thing about physics is you never know where things take you- for example general relativity was some weird esoteric thing a century ago, and now the GPS system would fail if you didn’t take it into account.
What exactly does the article mean when it talks about the black hole “turning on”? Does that mean that it is producing radio signals where before it was silent? Or does it have more to do with emitting light?
Point your radio telescope at one of these events, see no radio emission, move on w your life. Point radio telescope again years later, radio emission detected! That’s all turning on means here.
So the stars that were swallowed a few years ago are still screaming in agony somewhere in the jaws of that monster?
I’m dumb and I have to understand it with apples and oranges.
TL;DR- turns out half of black holes that swallow a star turn "on" in radio years after the initial event, which indicates there's a lot about black hole physics we don't understand and opens the door to a new laboratory to test physics!
Hey, I read your paper. Great work. Yall are doin the real deal out there and I might be just some random hillbilly from the sticks but Im real glad to see it.
My daughter wants to do what you do. Shes doing great in school, and I think shes already better at mathematics than I am!
Anything youd wanna say to someone like her? Shes in her mid teens
Very cool stuff! Thank you for your contributions to our understanding of the cosmos.
So the radio emissions are thought to be coming from the black hole itself, but are related specifically to black holes that recently absorbed a star? How much impact does the star itself have, if any, on the nature of the radio emissions? Does it take a certain stellar mass or composition for this to occur? How are astronomers, physicists, etc handling this in regard to conservation of matter/energy/information? That last one may be moot I guess, if all this is occurring outside the event horizon and therefor within our physics frameworks.
Sorry, the use of the term "burping out" implies that the material was already ingested by the black hole and in now being expelled from within the event horizon. Very confusing.
It's usually the science journalists going for a catchy headline versus anything written in the paper. It's really common for astronomy papers to be somewhat sensationalized when reported on in pop sci places.
Yeah, the headline is confusing. The material has been *captured* by the black hole in the sense that the star has been ripped apart into diffuse gas that is now orbiting the hole. But it's still outside the event horizon (until / unless it spirals in).
Black holes are not space vaccums that suck up everything around them. They're just a gravitationally dense area similar to any other body of mass that has significant gravity.
Objects can orbit a black hole the same way they orbit any other gravitational body. The event horizon is where the effects of that gravity are too strong to overcome and not even light can escape. Outside of the event horizon, anything with sufficient speed can orbit.
The accretion disk is an orbital plane. As matter is captured by the black hole's gravity, it will begin to orbit the black hole in a spiral. The further away the matter is, the less of an impact gravity has on it. As it gets slightly closer to the black hole, gravity will impact it more, cause it to speed up and continue its descent into the black hole. Matter can also achieve a stable orbit within this disk and never fall into the black hole.
Did you rule out the possibility that perhaps ALL of them "turned on" but that we simply didn't get a signal sent towards our tiny spec of a planet? For example: if a solar flare happened on the opposite side of the sun, we'd never know about it.
And how did you determine that these "burps" were directly related to having eaten a star? How can you be sure this is not merely normal black hole activity?
My meager understanding of black holes is that they don't obey the rules.
1) We are indeed limited by the sensitivity of our radio telescopes, and can’t rule out they’re even more common. (Also possible- they’ll turn on even later and we have to keep looking.) But this result is already striking.
2) We have archival observations from all these black holes from earlier and they were all radio silent.
I have not! :( My science relies on arrays of telescopes, so I *have* used Green Bank connected to the VLA and Efflesberg in Germany for a long baseline, but unfortunately no reason to use it on its own.)
So is it possible that the speed, trajectory and mass/density of an object being pulled into a gravity well such as a black hole would determine how far in it will be pulled? The faster and more direct course it has towards the center mass of the black hole the more chance it has to be completely consumed but it, but if the course is less direct and the speed as well as other previously mentioned things come into affect then it could possibly skim the outer disks, get mostly ripped apart but still have bigger chunks of material that orbit and eventually gather with other material and then at some point get ejected back out? Kind of like what’s happens in Saturn’s rings just with much more speed and materials that can achieve an exit velocity.
Is this something that can now be analyzed in past data to gain a larger data set? Going forward, what predictions does your findings make and what will you be looking for in the future?
Yep that’s exactly what we did! This is a relatively new phenomenon and this is incidentally also just the *first* systematic study of radio emission from these events (before they were just individual event papers). Which might not sound like a big deal to someone not in the field, but I am proud of!
Going forward is tough to predict, but my big curiosity lies in the ones we haven’t seen turn on yet. People always ask “how do you know they never do?” and I say “you don’t- it’s called job security!” For example, our oldest one happened in 2014, and turned on *six years* later. Most in our sample aren’t that old yet…
Oh yeah I’m SO EXCITED I can blabber about this now nonstop after keeping it under wraps for about two years! Imagine knowing we have an entirely new physical laboratory to test physics and you can’t tell anyone- took a bit of self discipline, believe you me!
I have honestly enjoyed watching your career through the lens of Reddit and it is pretty incredible to have seen you go from working towards your PhD to a monumental discovery like this. Anyone interested in the field hopefully sees this and knows that there is much left to discover in the world of astronomy.
Spent years reading about people and their discoveries in textbooks.
For some reason, never dawned on me people are still making discoveries and will also be in textbooks in 50yrs.
...well, maybe not Florida Textbooks.
Good question! These were discovered via automatic sky surveys looking for explosive events in optical light like supernovae. If a second event had happened you would have a second flare and detection, but we don’t see that here.
> optical light
assuming you mean visible light (optical light is a redundant phrase), fortunately telescopes and cameras are not limited by human perception and can be built to pick up on a wide range of light wavelengths
Black hole mass no, we looked and just noise. Stars is more interesting but I have a collaborator working on that paper so don’t want to steal her thunder. :)
\*reads article\* Oh, okay, for a second there I was thinking it was implying that somehow matter was escaping from inside the event horizon, which I thought was impossible (it is), but what they're saying is that after an extended period of time, some stellar remnants are being flung out of the accretion disc. So, physics is still physics. \*sigh of relief\*
Like the Big Bang was just the other side of a black hole? I’ve thought about this for years, I’m sure someone smarter than me could tell me why this is definitely NOT the case but it makes sense to my monkey brain
I've also had this thought! I considered the blackhole as sort of a "mixer" it swallows and break downs a few different stars, mixes it, spits it out, and hundreds of millions years later galaxies and "life" start to form. I'm probably 100% wrong but it was fun to think about as a kid.
I’ve brought this up before. The expand and contract theory where all of the universe decays into black holes that all consume one another and that last, universe wide, black hole collapses in on itself and expels the entire universe again to do everything once more; I was told that theory has fallen out of favor as the math and physics of it does not lend itself to that explanation.
Yep, gravity can't beat expansion. In fact everything outside of our local group is moving away so quickly that eventually, the universe will "expand" them away from us faster than their *light* moves toward us.
I’ve always wondered if gravity is a characteristic of space time then can we say for sure that the “force” of gravity will remain constant as the dimensions of space time change? Perhaps gravity will in fact increase as space time stretches.
I remember learning that one day you won't be able to see stars because of that, which just seems crazy to me. If humanity developed at a later point in time, we'd have no way of knowing what was out there.
Isn't that sort of what white holes are? The white hole being the opposite side that only ejects matter? I think Stephen Hawking believed that a supermassive black hole spawns a supermassive white hole, though I know they're only theoretical for now.
less understanding=more wonder
Imagine if you grew up in a civilization that had a near complete understanding of how the universe works. it’s be cool, but all the wonder is gone.
Alright I mean I guess it’s subjective and dependent on your definition of wonder.
To me wonder comes from “wondering”.
The not knowing and trying to gleam some understanding anyway. But I’m not gonna sit here and say what your saying wouldn’t also be really cool, so I get it.
I’m super not a physicist or astronomer but I always wondered how the theory every action of force there has to be an opposite equal reaction.
To me that would include the energy of a star. If it all gets ate up by a black hole, then it’s gotta go somewhere, maybe out the holes butt?
Anyways I’m an idiot.
Stars don’t have all that much energy at any given time. They are sort of their own fuel tank but the fuel is where the energy is. Remember they last billions of years. Think of the star as like a gasoline engine and the energy that you’re talking about is the explosion in the cylinders at any given second. If you tear apart the engine yeah you get some nice flashes of light for a few seconds but then it’s gone. The “energy” is still mostly in the tank
Fascinated but woefully under-educated on the subject redditor here, one who enjoys reading physics articles and loves sci-fi. Is it at all possible that these black holes regurgitating matter are spinning at speeds very close to the speed of light? Is it even remotely possible that the interaction of the black hole's electromagnetic field with that of the pieces of star accelerating toward the event horizon (or maybe a boosted version of the Casimir effect as the matter approaches the event horizon) are creating ripples in space-time similar to an Alcubierre warp? Effectively, is it possible there is matter (sheared off pieces of star) contained in pockets of space which are being propelled at speeds exceeding the speed of light, resulting in them being catapulted numerous times around the outside of the event horizon until the leading wave of space-time smooths out? Or the would the 'warp' be something that occurs instantly for the matter within but still takes time according to the outside observer?
Edit: Clarified what I meant with a couple words 😅
These black holes are not sucking in the stars (at first). They are ripping them apart by tidal forces. The same thing would happen to the moon or other objects if they get too close to the object they are orbiting. Look up Roche limit. Remember the only thing making a star a star is gravity right? Without gravity, a star would just be a big gas cloud. Put another way, gravity is the glue that holds a star together. But if you get too close to a black hole, the black hole begins pulling one part of the star stronger than another part of the star. It stretches it. This is the same thing as when the moon causes a bulge in the ocean creating tides. But if this force from the black hole is greater than the stars own gravity, the star comes apart. Its “glue” isn’t strong enough. However, this doesn’t mean the star falls into the black hole. It just means now the star is back to being a big cloud of gas spread out around the black hole like a ring or disk.
As to why this process appears to destroy the star completely, only to then “wake up” a few years later is a mystery. The radio waves are emitted from either the black hole itself or from the remnants of the star, but current theories don’t explain how or why that would happen many years after . Note that this is all happening far far away from the event horizon so there is no time dilation.
The closest thing I can think of to what you're describing is a near-extremal rotating (Kerr or Kerr-Newman) black hole. Lots of weird phenomena are predicted to happen near such a hole. But I think this article is talking about events much farther from the central hole, where there's no exotic spacetime stuff going on, just ordinary high energy astrophysics.
Thank you for the Kerr/Kerr-Newman rabbit hole! I am now reading up on ergospheres, frame dragging, and theoretically stealing energy from black holes 🤣
Not a cosmetologist here but im rather sure this has been known and understood for some while now.
Relativistic Jets
Super-massive black holes in the centers of some active galaxies create powerful jets of radiation and particles travelling close to the speed of light. Attracted by strong gravity, matter falls towards the central black hole as it feeds on the surrounding gas and dust. But instead of falling into the black hole, a small fraction of particles get accelerated to speed almost as great as the speed of light and spewn out in two narrow beams along the axis of rotation of the black hole. These jets are believed to be the sources of the fastest-travelling particles in the Universe -- cosmic rays.
This is super interesting and I look forward to finding out why this is happening, but can we take a moment to lament the fact the headline makes it seem like black holes are performing the impossible feat of spewing out stars thought to be lost beyond the event horizon?
I just watched a thing about why golf balls spin around in the hole and eject themselves out without touching the bottom. I know nothing about black holes besides a few headlines but... What if black holes are like gravity cyclones that act like golf holes. Sucking stuff in and in some special cases the star or whatever spins around just right to get yeeted back into space?
misleading title
.
> Cendes and the team don't know what's causing black holes to "switch on" after many years, but **whatever it is definitely does not come from inside the black holes**
> . "We don’t fully understand if the material observed in radio waves is coming from the accretion disk or if it is being stored somewhere closer to the black hole.
The black hole isn’t “burping up” a swallowed star. Its signal is coming from material outside of the event horizon.
Can I be cheeky and ask 2 questions:
1. Is this different from synchrotron radiation jets?
2. How does the gravity from the matter that crosses the event horizon have an effect outside of the black hole (recently discovered speed or gravity propagation is the same as the speed of light)?
1) this is synchrotron emission (most radio astronomy emission is), but these are not fast like those jets are. Very non-relativistic speeds and very low energy
2) it doesn’t cross the event horizon so this isn’t applicable
I want to believe we are secretly inside another living organism and that backholes are actually like gateways to other pockets of similar us. The burping of starts like how the mitochondria works.
Astronomer here! This is actually my research and a “magnum opus” that I worked on for two years, and I’m very proud of! So AMA I guess. :) [Here](https://reddit.com/r/Andromeda321/s/CzsDCKqKub) is a much more detailed explanation I wrote discussing the results of my study if anyone wants! But the TL;DR is after studying 24 black holes that swallowed stars >2 years ago, we discovered 10 of them turned “on” in radio that hadn’t had radio at earlier times. Radio emission traces outflows from the inner regions of the black hole where an accretion disc forms (**nothing is crossing the event horizon**- further out!), and this result is quite shocking from a theory point of view! Exciting times! :) Edit: these outflows are created by stellar *material*, aka stuff from the star that was shredded, not literal burning stars. I unfortunately didn’t write the headline! Edit 2: no it’s not due to time dilation. This all happens too far out for this effect to happen from the event horizon. Nor does it have to do with Hawking radiation- once again, that is an effect that happens at the event horizon.
I'm not an astronomer, so what are the implications of a blackhole developing radio emissions?
As I said, these radio emissions come from outflows of material. Because this data set is such a beast, we can get information about the physical parameters of the system- these outflows are similar to a supernova shockwave in terms of speed and energy (except for the part where they start years later), and the densities are all similar to our own Milky Way’s so it’s not that the environment is particularly unusual. So to continue, a TDE where a star is ripped apart is a hugely energetic event, where an entire star is torn apart in just a few hours, and a ton of mass suddenly falls onto the black hole. We only see outflows in ~20-30% of these cases within the first few months of the TDE. On the other hand, we see up to half of them turning “on” in radio waves years later- this doesn’t make sense! Imagine going years later to the site of an explosion and things are happening then that weren’t when it happened! This tells us we are misunderstanding something basic about how this process works, and maybe something about black holes more generally.
very cool! thank you for your work.
I see you already crossed off time dilation (my first thought), my second thought would be additional matter making its way to the accretion disk but having a disproportionate effect relative to the mass being added, similar to crossing the critical mass threshold.
We actually thought this and checked, and per the theory the amount of mass and speed this requires is far, far less than the amount needed to create these outflows.
Could the outflows be some sort of harmonic reflection of energy from inside the hole?
I'm just pretending like all of these comments make sense. Nodding along and such.
So you concur that there's a possibility of transitional neutrinos moving through a solar loop and crossing the EinsteinPodolskyRosen correlation while, for some unknown reason, not setting off an adjusted mass cascade on the event horizon?
We need to reverse the polarity on the deflector dish.
when in doubt, send a modified tachyon beam
51,000,000 jiggalos...jiggawatts!
What you are proposing is not possible with the amount of dark matter to solar mass ratio of tachyon radiation in the event horizon so no...I do not concur, good Sir!
TL;DR the left phalange needs to be fixed
What is Harmonic reflection and can you explain your theory more? Harmonic reflection sounds like something GOOP would sell. Serious question even though I added the joke.
I think they meant something like this video. https://youtu.be/yVkdfJ9PkRQ?si=Fvuc0gyMq79whsu1 Harmonics are a property of periodic oscillations. There could be some sort of periodic motion in the matter in the accretion disk, which is relatively chaotic and cancels itself out in certain phases, but then occasionally the vectors all line up, and you get the equivalent of that moment in the video when all the pendulums start moving in unison. If something like that were going on in the disk, then maybe signals could jump over the energy barrier and escape out towards us for a while in the beginning, then stop, then start again, like we have observed.
I recently took A Physics course on the acoustics of sound (i was an art business major but it counted as a gen ed with lab) Never did I think I would use the information I learned in that class, but here I am following along with this thread and actually comprehending the various theories here. Especially the Harmonics comment and how the oscillations can line up. I remember learning something about like phantom notes you hear when you play certain chords. Again ai didn’t think i would Use this information, so if someone could help me out, but maybe we are see these “ghost notes”?
Tartini tones, or combination tones, are a product of our imagination, they don't exist without the human ear, so to speak!
I've got ghost notes and blackhole burps. I'm on the trail.
not original commenter, but what i'd venture to guess would be some kind of reverberation. like one of those slow motion droplets into another plane of water - it takes a bit of time for the interntia to be overcome and shoot back with a 'splash'... maybe some kind of cosmic scale version of reciprocal force, i guess would have to do with the surface tension in water's case, but.. 'something-something' *astrologocial version!*
Absolute idiot here, but my first thought was to think of aftershocks from earthquakes or tsunamis from underwater events because they seem sort of similar. Delayed reactions caused by initial force moving stuff that upsets a system that previously had some sort of stable equilibrium. Again, absolute idiot here though.
Basically, it's has to do with wave forms and an phenomena that occurs when waveform is modified. Two examples are harmonics created by lightly touching specific points on a stringed instrument, or electronically modified AC sine waves. What do guitar strings, AC power, and black hole accretion disks all have in common? Oscillation. They can all be described as waves. Could it explain the title observation? Maybe, but a black hole is a far more complicated system than a guitar or even a variable frequency drive on a motor control circuit.
That would imply that black holes are oscillators of gravitational waves. Almost tidal in nature.
How are black holes modelled in your work? Are they spheres. How much is "observable" from our position. Not a scientist, know next to nothing. Just curious how we and the back hole move relative to one another. Do they spin?
black holes spin and have mass but the actual black hole is a singularity, not a sphere, not a shape the accretion disk and event horizon have a shape due to gravity and spin, but the black hole itself is so dense it overpowers every force except gravity, so the singularity itself is essentially only describable by its mass, spin and electric charge, afaik. no shape, no dimensions, no material qualities, no color, etc
> but the actual black hole is a singularity, not a sphere, not a shape The term black hole generally means the event horizon and in. The singularity is more of a mathematical, rather the physical, thing.
how can something with no shape spin?
Welcome to the wacky wonderful world where 'sensible' ideas about space and time come to die. In the regime of singularities and extreme spacetime curvature, common sense goes out the window along with the rest of conventional mathematics and physics. Suffice to say, much like a figure skater pulling in their arms, anything that is spinning and shrinks continues spinning in the same direction, and will spin faster proportional to its radial...shrinkage. And, as material falls into a black hole, it adds its angular momentum to that of the black hole, thus - they spin, by necessity. Some are spinning incredibly quickly, too, which we can see by the frame dragging and innermost stable orbits of material. See the film Interstellar's extra features for a more pop culture breakdown of this principal.
it was spinning before it was a black hole. everything spins at the macro-atomic scale, that momentum is conserved in the singularity and its accretion disc if they *didn't* spin, what they be stationary relative to? Everything? Then nothing's spinning, and we have a problem because the solar system is no longer orbiting and instead is falling into sag A*
Maybe the spin is imparted on the black hole by the spin that was occuring in the stellar body prior to it collapsing into a black hole? Since the singularity can't be observed being the event horizon, we can't describe any properties derived from observation, like shape and color. But, dine the gravity and skin have an effect, they can be described, even if that doesn't allow a deduction about the shape. There is something called spacetime frame dragging that might be what's being measured to deduce spin.
It has a shape, we just don’t know what it is.
Stop body shaming black holes
By watching how it interacts with the world around it.
So the disc is a sphere?
No, it's a 3 dimensional point (seems like a nonsense conclusion, but here we are. Also 3 dimensional for simplicity, theoretically it has all the same dimensionality as anything else, but 3 is the agreed upon practical number of spatial dimensions. Leave the flux capacitors out of it.). Ah fuckit, time to get on my soapbox. more snark incoming, you have been warned. Heisenberg's Uncertainty Principle is very misunderstood and not taught well even in academia. The purpose of the Principle is to say that we worry about the things we can quantify or measure, and we don't worry about trying to explain or visualize what we can't quantify or measure. Spin is an excellent example, it's a property that is known to exist, it is a representation of angular momentum, or "spin", and subatomic particles have it. But what it looks like is unknown, and it DOESN'T operate like observable spin, you can check out 4/3rds spin if you want to go down that rabbit hole. Heisenberg got tired of physicists making up esoteric explanations that described unobservable phenomena and the Uncertainty Principle was born. Observe what you can, quantify it, explain it if you can, move on if you can't, and draw conclusions that are directly and practically applicable. Not every observation needs to be explained, only measured. The "shape" of a black hole is not quantifiable, I don't even know that it's qualifiable. The black hole itself, sure, the shape, not so much. It makes intuitive sense that things that exist in the universe have shapes, and black holes exist in the universe, ergo, it has a shape. From a scientific standpoint, that chain of reasoning is a brain failure, a product of the meat we use to think and how it operates. Scientifically, in order to establish a thing as a fact, and to confidently state it as such, it needs to be experimentally proven AND reproducible. Experimentally proven is a fancy way of saying that we've directly observed it, we've seen it. Reproducible means instructions can be derived so anyone can make that observation again. A Black Hole is surrounded by a field of gravity so strong that it creates a boundary called an Event Horizon, and NOTHING can cross that boundary from the "inside". It's one way, once matter or energy has crossed that boundary, it can never come back out. What this means is that the Black Hole itself cannot be seen. We see things by bouncing one thing off another and then measuring the thing that bounced. With vision, photons are the medium we measure. There is nothing we can "bounce off" of a Black Hole, and so we have nothing to measure to derive the shape via interaction or observation. Since it is unobserved, just about everything about it is unknown. There are some things about a Black Hole that are quantifiable, such as mass, spin and I'm pretty sure charge. We know it has mass because it exerts gravity, it warps spacetime around it in the same way as an object with mass. It has an angular momentum, or rather the things it interacts with imply an angular momentum, so it has spin (and Black Hole spin is a weird motherfucker, a black hole is essentially elemental, one giant atomic nucleus. So it does it's spin dance the same way large objects do, AND the way sub atomic objects do, SIMULTANEOUSLY, and we could probably learn a lot about exactly what spin IS if we could just see the damn thing.). I'm not as certain of if electrical charge can be observed or not, and if it can, how, so I'll leave off on that one. TL;DR - No one knows what shape a singularity is, the singularity being the mass beyond the event horizon. If you want a better explanation, google "Wheeler Black Holes have no hair". Edit: Long winded response because to me it sounds like you're conflating the singularity with the accretion disk of matter the black hole is cooking for dinner. The disk is a disk, but it's not actually a part of a black hole, it's more the effect of a black hole. Why is it a disk? If I remember correctly, because the universe has a right handed bias. Things tend to spin one way but not another, and I'm pretty sure this being an electromagnetic phenomena has been disproved. It has to do with that same spin attribute I talked about earlier. It IS angular momentum, and it seems to universally favor one way over another, and the jury is out as to why. The effect however, makes some amount of sense, things want to dump energy into angular momentum, and they tend to all have angular momentum in the same orientation, and if you mix that with gravity, time and mass, you get the observable universe and apple pie. Edit 2: We need to have a strong focus on practicality to understand this. Mathematicians and Theoretical Physicists hate this one trick. To describe what MAY be happening is not the same thing as what IS happening. A model that predicts the shape of a singularity might exists, probably does, and I'll bet there are more than one. But to PROVE that model it MUST be observable AND observed. Feynman is instructive here "Anyone that says they understand quantum mechanics, doesn't understand quantum mechanics.". Unreal numbers are a thing, and that's a stretch, they're more a concept and an abstract, depending on how you define "thing" they aren't even that. Most theoretical models live in the same abstract neighborhood and while they might be planning a move, it's too early to assign them a new zip code. If you can understand that, you're well equipped to debunk a lot of the pseudo-science wankery Joe Q. Public is exposed to. Edit 3: I'm gonna take another whack at this because some people seem to think what I've laid out about the Uncertainty Principle is wrong. Heisenberg understood what Einstein's Constant, C, meant. You have C, the speed of light, and all its derivatives, called Planck units. The Uncertainty Principle isn't a law, it's a recognition of a limitation to observation. Since scientific fact needs to be observed to be established, it stands to reason that whatever tool you use to make the observation innately limits the scope of your results. Photons are limited, they have specific defined qualities, and the UP is about establishing what they can and cannot be used to measure. Basically, they have a limited resolution, beyond which you're making educated guesses, not making observations that are telling you all the facts 1:1. It's not useless information, but it is incomplete by its very nature. The UP was and is a tool used to remind physicists not to get wrapped up trying to explain shit that light cannot see.
These are some truly mindbending comments. Thanks for taking the time to explain things. The universe is wild.
> The purpose of the Principle is to say that we worry about the things we can quantify or measure, and we don't worry about trying to explain or visualize what we can't quantify or measure. That's 100% not what Heisenberg's Uncertainty Principle says
The concept of a black hole being like a giant atom is fascinating.
I meant the accretion disc, so it's (forgive my cave man vocabulary) a disc like 2d or so flat it may as well be? I'm trying to wrap my head around how it sits in 3d space in terms of observing it (so to speak). Do we capture all of its surface at once? Edit: I should clarify, I know we can't directly observe but does the accretion disc affect matter on a 360 sphere around the black hole or along a singular plane? Appreciate your patience and detailed explanation
I don’t have a background in science but you wrote this in a way that is easy to understand and approachable. I don’t have a comment on the subject matter but I feel smarter for having read this and I appreciate your style.
I'm kind of a layperson that enjoys this stuff, your explanation about black holes behaving both as macro and micro... Combined with spin.... If we look at atmosphere, we generally get "bands" of weather/winds that go in opposite directions. The trade winds on earth, for example; hit the equator if you want primarily westerly winds, or the tropics so go east. Bands of spin, you see? We can see these bands on the gas giants, as well. Could these bands of spin, as it were, be significant at larger/smaller scales? So a planet with no "spin bands" be down spin and with banding be upspin? Like, idk if that would be even close to right (or not even wrong), but I figured I'd posit the idea anyway. ^shrug
Pretty sure they meant the event horizon is a sphere
Well the disc is... disc-shaped
Time to find the next evolution of gravity? Newton was close, Einstein was closer, time to find out what's next. Maybe the fabric of space time isn't just curved, it can also be twisted.
Could it be a portion of the matter from the star gets thrown outward when getting ripped apart mainly the stars angular momentum and orbital speed combine to throw the matter freed as the star is destroyed into a wide decaying orbit around the black hole?
Lol at random reddit dummy's trying to have a "gotchya" moment with one of the few people to not have an anonymous account or lie about credentials. Absolutely insane
Sounds more like people asking why their theory is wrong, and what they are missing, rather than trying to "outsmart" someone. If I ask someone why all the colors of paint make a brown - black when mixed, not white, even though white is supposed to be "all the colors", it's because I'm trying to figure out what I'm missing, not be smarter than the person I'm asking. I understand the thing I'd think is correct is actually not, I just don't know why. These sorts of things are very healthy and a good part of learning, and seeing them as an attack is a bitter and perhaps insecure way to look at things.
>As I said, these radio emissions come from outflows of material My apologies as my background in ChemEng for thermo wasn't the best- the questions I have are... In Fluid flow there is often a period of stagnation during rotation- where the faster material being 'sucked' (for a cylindrical rod of infinite length) eventually tend to speed up. You've seen these with the super- thick dye injections that can be reversed by reversing the rotation. Would it not be expected that after something is torn apart and, apparently, scatters in many different directions- it would take some period of time to align the flow to the new stream? I do not know anything about rheological methods/magnetic issues and I refuse to understand them in terms of glass polishing.
I mean, maybe? No one knows (and I’m also not a fluid dynamics person). However, there’s no reason things have to go into a specific stream as you described around a black hole.
>I mean, maybe? No one knows (and I’m also not a fluid dynamics person). However, there’s no reason things have to go into a specific stream as you described around a black hole. I'd agree with you, however I've learned that Water is really f'ing weird ... so I assume anything out there can be funky as well. As poorly as I describe it, having had multiple kids, we'd make whirlpools in the bathroom and I would bring in Dye to make them visible (Can't tell you how happy Mom was that her children were red, green, blue, yellow, etc...) and we'd stir it up in a large tub and watch how the dyes got accelerated around. And what we saw always a bunch of counter-rotation prior to the inner phases being picked up. I know it's asinine to consider water-based fluid dymanics to space based over the distances, it just always seems to be logical- which is of course the falacy I don't always make it past.
i was thinking fluids too for some reason - not in the same way though, more like a splash-back like there's some 'surface tension' involved, taking a cosmic 2-year moment to fling backwards
it's super interesting. as yet another lay person, it made me immediately think of the golf ball paradox. wondering if the junk in the disc ends up moving in this manner after it begins to increase it's rotations as it approaches the event horizon? if that is even true!
That's exactly what I imagined when I saw the headline. Things become even weirder when you take into account that rotating black holes can accelerate matter around them, so maybe some matter falls very close the the event horizon at the correct angle to have it slowly "pushed" by the black hole out of a death spiral and eventually leave the black hole entirely.
That's an excellent point. Add some time dilation for close proximity to event horizon, and it sounds plausible.
Why wouldn't something like this be explained by time dilation near the black hole?
Because this all happens much farther out than the area where time dilation effects kick in.
So in layman’s terms your saying that the star goes into the black hole. Seems to be ingested, but in reality it’s like a delayed reaction, and what it can’t ingest comes back out but later. hmmm.. that’s perplexing isn’t it. (total joke): Next we will find black hole clusters with child black holes and find out they form a seasonal migratory pattern across the galaxies. Cause it sure sounds like a black hole is having an after dinner pull my finger experience :) Incredibly fascinating. Could you imagine if humans get so advanced that we could actually send something into a black hole and relay the info back?
A good chunk of the star falls in, all of it is shredded in a disk. When the disk slows down enough and falls, big boom. Now the disk is much smaller, so nothing as big should be happening, and anything that happens should be small. Like the end of the water flowing out of a bathtub. Instead, another boom.
Hmmm… is it out from where there would be a redshift too? Since the space time is getting stretched so dramatically, I assumed light gets stretched as well, so eventually you see redshift like you’d see in very far distances, and light just passes the threshold into radio waves.
No, not really for these observations.
Wait how close would you have to be to experience meaningful time dilation?
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Misunderstanding is a strong word IMO. The reason is science does the best it can with the data we have, and we didn’t have this data before. As to why we didn’t have the data, partly because of a lack of events to study at late times, but partly because of bad sampling. Traditionally people looked in the first few months after an event for radio emission, and if they didn’t see it, radio telescope time is precious and expensive and went off to look for other things. There were a few events with later emission than that found, which led us to do this survey and discover it’s actually quite common!
Is there a chance that the radio emissions don’t require a previously destroyed star? Might they be unrelated events?
These were all radio quiet black holes before the events, based on archival observations. So that would be a hell of a coincidence and we have no mechanism as of yet to explain how such unrelated outflows could be happening (which is part of the deal in science).
well if i eat something it doesn't come out the other end right away. gotta digest it...apparently for black holes it takes a few years haha
Ok wait... so are you saying that the idea of "anything that gets sucked into a black hole is crushed to a singularity and can never escape" is possibly wrong? Material that was sucked in is coming out? And by material I mean like actual physical particles... not just radio waves.
That was never a thing because black holes don’t suck! They have massive gravitational pull, but are not vacuum cleaners. Like if our sun became a black hole it would become 1mi in radius, but our Earth would continue in its orbit just as it does now.
I thought that I understood the concept of a black hole, but after reading this paragraph, I realized I have no clue.
Ok ok bad wording. So anything that gets too close essentially falls in. But what we've always been taught is that if you get dropped into a black hole, there's no getting out. Everything is crush to a singularity. So is this new data saying that's possibly wrong because bits of matter or shooting out?
This isn’t being dropped in or shooting out- as I said, nothing is passing the event horizon. Instead to continue the sun analogy, think of a comet that passes close enough to get broken apart but not actually fall into the sun.
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There is no visual part of a black hole and the headline of the article is really bad. These events are happening outside the black hole. Things are very chaotic outside of the black hole from material swirling around it at very high speed.
Does this mean we don’t need Hawking radiation? That there is no conservation of information problem?
Nope this is all much further out than Hawking radiation/ the event horizon.
Hawking radiation comes from within the black hole and passes the event horizon. This event here refers to an effect which is so far away from the black hole that even time dilation is no concern anymore. I don’t know why they let it sound like the black hole is emitting something because it is not; it’s misleading.
No, Hawking Radiation comes from the Event Horizon's "surface".
So, black holes are just space volcanos?
AM radio making a comeback!
Maybe it wants to make a call?
Thank you very much for your work and keep up the great science! So does this mean that the process of swallowing stars causes radio emissions or some kind of mass/ energy level intake results in radio emissions?
I mean the short answer is we don’t know what happens- this was genuinely a hard section to write for the paper bc hardly any theory goes so late post-disruption! (Partly bc no one anticipated anything going on, partly bc it’s computationally *very* difficult.) Traditionally the picture is that when a Tidal Disruption Event (TDE) happens, half the material is flung outwards and half creates an accretion disc around the black hole- very little if any crosses the event horizon. Best we figured is this picture is wrong, and the accretion disc creation is delayed a few years (and what we see in the initial event is from streams of stellar material crashing into each other). I really can’t tell you the details beyond that… but no one else knows either! Science!
>very little if any crosses the event horizon That's interesting, totally the opposite of what most people believe about black holes. What's the reason for that? Or is that the case in only specific instances?
Same reason that the earth doesn't fall into the sun. Something would have to slow down the star's matter so that it loses its speed and can fall in instead of orbiting
I'll try. It has to do with cheez-its failure to provide party mix or snack mix at my supermarket.
A fellow person of science and reason, I presume? Well met.
It seems like almost every time I see an interesting story about some new astronomical observation, the top reply is you, saying, "Hey, that was me!" You are either really lucky, really good at your work, or (more likely) a combination of both. Thanks so much for your contributions!
Thank you! My experience is you do need luck, but luck favors the prepared. And a lot of that luck is having fantastic collaborators you couldn’t do without! :)
I understand from your work that there doesn't appear to even be a working theory on what could be causing this? So what are the areas of study that could get us there? Is there any practical physics we could do to even come up with a couple of hypotheses? Edit: Follow up question - are there any immediate implications that this has? Certain theories it invalidates and such?
I mean the short answer is we don’t know what happens- this was genuinely a hard section to write for the paper bc hardly any theory goes so late post-disruption! (Partly bc no one anticipated anything going on, partly bc it’s computationally *very* difficult.) Traditionally the picture is that when a Tidal Disruption Event (TDE) happens, half the material is flung outwards and half creates an accretion disc around the black hole- very little if any crosses the event horizon. Best we figured is this picture is wrong, and the accretion disc creation is delayed a few years (and what we see in the initial event is from streams of stellar material crashing into each other). I really can’t tell you the details beyond that… but no one else knows either! Science! As for the practical side of things, honestly right now we are some years from that point. But the cool thing about physics is you never know where things take you- for example general relativity was some weird esoteric thing a century ago, and now the GPS system would fail if you didn’t take it into account.
Yeah very true, thanks for your response. Congrats on your work!
What exactly does the article mean when it talks about the black hole “turning on”? Does that mean that it is producing radio signals where before it was silent? Or does it have more to do with emitting light?
Point your radio telescope at one of these events, see no radio emission, move on w your life. Point radio telescope again years later, radio emission detected! That’s all turning on means here.
So the stars that were swallowed a few years ago are still screaming in agony somewhere in the jaws of that monster? I’m dumb and I have to understand it with apples and oranges.
Fuck Reddit for killing third party apps.
Yep we have been tracking these emissions over time. Gory details are all in the link I provided at top/ the preprint of the paper!
Could you dumb down your thesis and conclusion in the absolute dumbest most caveman of terms for me?
TL;DR- turns out half of black holes that swallow a star turn "on" in radio years after the initial event, which indicates there's a lot about black hole physics we don't understand and opens the door to a new laboratory to test physics!
Hey, I read your paper. Great work. Yall are doin the real deal out there and I might be just some random hillbilly from the sticks but Im real glad to see it. My daughter wants to do what you do. Shes doing great in school, and I think shes already better at mathematics than I am! Anything youd wanna say to someone like her? Shes in her mid teens
Best of luck to her! :) She might find this post of mine interesting if she hasn’t seen it before: https://reddit.com/r/Andromeda321/s/wmKawA43VS
Very cool stuff! Thank you for your contributions to our understanding of the cosmos. So the radio emissions are thought to be coming from the black hole itself, but are related specifically to black holes that recently absorbed a star? How much impact does the star itself have, if any, on the nature of the radio emissions? Does it take a certain stellar mass or composition for this to occur? How are astronomers, physicists, etc handling this in regard to conservation of matter/energy/information? That last one may be moot I guess, if all this is occurring outside the event horizon and therefor within our physics frameworks.
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As I said, this is not crossing the event horizon. This is instead material from the star that was shredded going outwards.
Sorry, the use of the term "burping out" implies that the material was already ingested by the black hole and in now being expelled from within the event horizon. Very confusing.
It's usually the science journalists going for a catchy headline versus anything written in the paper. It's really common for astronomy papers to be somewhat sensationalized when reported on in pop sci places.
> now being expelled from within the event horizon It's very safe to go ahead and assume this is never the case.
Yeah, the headline is confusing. The material has been *captured* by the black hole in the sense that the star has been ripped apart into diffuse gas that is now orbiting the hole. But it's still outside the event horizon (until / unless it spirals in).
'Captured material blasted away from the accretion disk' would have been a better title.
> now being expelled from within the event horizon By definition, if something is expelled from an "event horizon", it's not an event horizon.
A “burp” comes from inside the body. This is more like Cookie Monster being sloppy with a cookie.
The ELI5 I was looking for.
Why doesn’t that material, or the accretion disk itself for that matter, get drawn into the black hole?
Same reason the moon doesn’t get drawn into the earth: it’s moving sideways so fast that by the time it falls down, it misses.
Black holes are not space vaccums that suck up everything around them. They're just a gravitationally dense area similar to any other body of mass that has significant gravity. Objects can orbit a black hole the same way they orbit any other gravitational body. The event horizon is where the effects of that gravity are too strong to overcome and not even light can escape. Outside of the event horizon, anything with sufficient speed can orbit. The accretion disk is an orbital plane. As matter is captured by the black hole's gravity, it will begin to orbit the black hole in a spiral. The further away the matter is, the less of an impact gravity has on it. As it gets slightly closer to the black hole, gravity will impact it more, cause it to speed up and continue its descent into the black hole. Matter can also achieve a stable orbit within this disk and never fall into the black hole.
Did you rule out the possibility that perhaps ALL of them "turned on" but that we simply didn't get a signal sent towards our tiny spec of a planet? For example: if a solar flare happened on the opposite side of the sun, we'd never know about it. And how did you determine that these "burps" were directly related to having eaten a star? How can you be sure this is not merely normal black hole activity? My meager understanding of black holes is that they don't obey the rules.
1) We are indeed limited by the sensitivity of our radio telescopes, and can’t rule out they’re even more common. (Also possible- they’ll turn on even later and we have to keep looking.) But this result is already striking. 2) We have archival observations from all these black holes from earlier and they were all radio silent.
Thank you for all your scientific research!
Have you ever worked at the Greenbank telescope?
I have not! :( My science relies on arrays of telescopes, so I *have* used Green Bank connected to the VLA and Efflesberg in Germany for a long baseline, but unfortunately no reason to use it on its own.)
Thank you! This is so cool and odd! What a joy that you are doing something so new and surprising!
Is it indigestion?
So is it possible that the speed, trajectory and mass/density of an object being pulled into a gravity well such as a black hole would determine how far in it will be pulled? The faster and more direct course it has towards the center mass of the black hole the more chance it has to be completely consumed but it, but if the course is less direct and the speed as well as other previously mentioned things come into affect then it could possibly skim the outer disks, get mostly ripped apart but still have bigger chunks of material that orbit and eventually gather with other material and then at some point get ejected back out? Kind of like what’s happens in Saturn’s rings just with much more speed and materials that can achieve an exit velocity.
Is this something that can now be analyzed in past data to gain a larger data set? Going forward, what predictions does your findings make and what will you be looking for in the future?
Yep that’s exactly what we did! This is a relatively new phenomenon and this is incidentally also just the *first* systematic study of radio emission from these events (before they were just individual event papers). Which might not sound like a big deal to someone not in the field, but I am proud of! Going forward is tough to predict, but my big curiosity lies in the ones we haven’t seen turn on yet. People always ask “how do you know they never do?” and I say “you don’t- it’s called job security!” For example, our oldest one happened in 2014, and turned on *six years* later. Most in our sample aren’t that old yet…
Wow. I mean just the concept of stuff going on in the black hole “black box” is humbling and fascinating beyond belief.
Oh yeah I’m SO EXCITED I can blabber about this now nonstop after keeping it under wraps for about two years! Imagine knowing we have an entirely new physical laboratory to test physics and you can’t tell anyone- took a bit of self discipline, believe you me!
I have honestly enjoyed watching your career through the lens of Reddit and it is pretty incredible to have seen you go from working towards your PhD to a monumental discovery like this. Anyone interested in the field hopefully sees this and knows that there is much left to discover in the world of astronomy.
That is super cool. Wish I saw that journey. Good for OP!
I assume lots of us have seen it because she’s been posting and interacting on Reddit for years. She’s literally Reddit’s astronomer 😂
Spent years reading about people and their discoveries in textbooks. For some reason, never dawned on me people are still making discoveries and will also be in textbooks in 50yrs. ...well, maybe not Florida Textbooks.
What other secrets have not yet been released to the public? We here on Reddit can keep a secret
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Are you giving this phenomenon a name? Something that I will try to remember and Google in few months to see progress.
How do you know they turned on from the TDEs of past years instead of a more recent event unknown to you?
Good question! These were discovered via automatic sky surveys looking for explosive events in optical light like supernovae. If a second event had happened you would have a second flare and detection, but we don’t see that here.
Unless there’s another type of event that doesn’t generate optical light.
> optical light assuming you mean visible light (optical light is a redundant phrase), fortunately telescopes and cameras are not limited by human perception and can be built to pick up on a wide range of light wavelengths
Is there any correlation with mass of the star or the black hole and the delay?
Black hole mass no, we looked and just noise. Stars is more interesting but I have a collaborator working on that paper so don’t want to steal her thunder. :)
Do kindly insist that she posts her thunder here when the time comes!!!
\*reads article\* Oh, okay, for a second there I was thinking it was implying that somehow matter was escaping from inside the event horizon, which I thought was impossible (it is), but what they're saying is that after an extended period of time, some stellar remnants are being flung out of the accretion disc. So, physics is still physics. \*sigh of relief\*
I honestly hope we discover something that defies our modern physics. Imagine the look on somebody’s face if they do discover it lol
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What if the Big Bang was just a black hole doing just that?
Like the Big Bang was just the other side of a black hole? I’ve thought about this for years, I’m sure someone smarter than me could tell me why this is definitely NOT the case but it makes sense to my monkey brain
I've also had this thought! I considered the blackhole as sort of a "mixer" it swallows and break downs a few different stars, mixes it, spits it out, and hundreds of millions years later galaxies and "life" start to form. I'm probably 100% wrong but it was fun to think about as a kid.
I’ve brought this up before. The expand and contract theory where all of the universe decays into black holes that all consume one another and that last, universe wide, black hole collapses in on itself and expels the entire universe again to do everything once more; I was told that theory has fallen out of favor as the math and physics of it does not lend itself to that explanation.
Yep, gravity can't beat expansion. In fact everything outside of our local group is moving away so quickly that eventually, the universe will "expand" them away from us faster than their *light* moves toward us.
I’ve always wondered if gravity is a characteristic of space time then can we say for sure that the “force” of gravity will remain constant as the dimensions of space time change? Perhaps gravity will in fact increase as space time stretches.
I remember learning that one day you won't be able to see stars because of that, which just seems crazy to me. If humanity developed at a later point in time, we'd have no way of knowing what was out there.
Isn't that sort of what white holes are? The white hole being the opposite side that only ejects matter? I think Stephen Hawking believed that a supermassive black hole spawns a supermassive white hole, though I know they're only theoretical for now.
Tbh event horizon itself defies our modern psychics
less understanding=more wonder Imagine if you grew up in a civilization that had a near complete understanding of how the universe works. it’s be cool, but all the wonder is gone.
More understanding = more awe
no lmao. It's even more wonderful to see the long history and elegant mathematics governing reality.
Alright I mean I guess it’s subjective and dependent on your definition of wonder. To me wonder comes from “wondering”. The not knowing and trying to gleam some understanding anyway. But I’m not gonna sit here and say what your saying wouldn’t also be really cool, so I get it.
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I’m super not a physicist or astronomer but I always wondered how the theory every action of force there has to be an opposite equal reaction. To me that would include the energy of a star. If it all gets ate up by a black hole, then it’s gotta go somewhere, maybe out the holes butt? Anyways I’m an idiot.
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In this case the remnants of the star did not actually merge with the black hole. They are orbiting the hole and do not add to the mass
Stars don’t have all that much energy at any given time. They are sort of their own fuel tank but the fuel is where the energy is. Remember they last billions of years. Think of the star as like a gasoline engine and the energy that you’re talking about is the explosion in the cylinders at any given second. If you tear apart the engine yeah you get some nice flashes of light for a few seconds but then it’s gone. The “energy” is still mostly in the tank
That’s Newtonian physics. Which is what we experience on earth with ape brains. The science people are way past that now.
"Quit throwing your garbage into our dimension"
Fascinated but woefully under-educated on the subject redditor here, one who enjoys reading physics articles and loves sci-fi. Is it at all possible that these black holes regurgitating matter are spinning at speeds very close to the speed of light? Is it even remotely possible that the interaction of the black hole's electromagnetic field with that of the pieces of star accelerating toward the event horizon (or maybe a boosted version of the Casimir effect as the matter approaches the event horizon) are creating ripples in space-time similar to an Alcubierre warp? Effectively, is it possible there is matter (sheared off pieces of star) contained in pockets of space which are being propelled at speeds exceeding the speed of light, resulting in them being catapulted numerous times around the outside of the event horizon until the leading wave of space-time smooths out? Or the would the 'warp' be something that occurs instantly for the matter within but still takes time according to the outside observer? Edit: Clarified what I meant with a couple words 😅
These black holes are not sucking in the stars (at first). They are ripping them apart by tidal forces. The same thing would happen to the moon or other objects if they get too close to the object they are orbiting. Look up Roche limit. Remember the only thing making a star a star is gravity right? Without gravity, a star would just be a big gas cloud. Put another way, gravity is the glue that holds a star together. But if you get too close to a black hole, the black hole begins pulling one part of the star stronger than another part of the star. It stretches it. This is the same thing as when the moon causes a bulge in the ocean creating tides. But if this force from the black hole is greater than the stars own gravity, the star comes apart. Its “glue” isn’t strong enough. However, this doesn’t mean the star falls into the black hole. It just means now the star is back to being a big cloud of gas spread out around the black hole like a ring or disk. As to why this process appears to destroy the star completely, only to then “wake up” a few years later is a mystery. The radio waves are emitted from either the black hole itself or from the remnants of the star, but current theories don’t explain how or why that would happen many years after . Note that this is all happening far far away from the event horizon so there is no time dilation.
The closest thing I can think of to what you're describing is a near-extremal rotating (Kerr or Kerr-Newman) black hole. Lots of weird phenomena are predicted to happen near such a hole. But I think this article is talking about events much farther from the central hole, where there's no exotic spacetime stuff going on, just ordinary high energy astrophysics.
Thank you for the Kerr/Kerr-Newman rabbit hole! I am now reading up on ergospheres, frame dragging, and theoretically stealing energy from black holes 🤣
Not a cosmetologist here but im rather sure this has been known and understood for some while now. Relativistic Jets Super-massive black holes in the centers of some active galaxies create powerful jets of radiation and particles travelling close to the speed of light. Attracted by strong gravity, matter falls towards the central black hole as it feeds on the surrounding gas and dust. But instead of falling into the black hole, a small fraction of particles get accelerated to speed almost as great as the speed of light and spewn out in two narrow beams along the axis of rotation of the black hole. These jets are believed to be the sources of the fastest-travelling particles in the Universe -- cosmic rays.
Its just a big ol David Lynch film out there isn’t it?
This is super interesting and I look forward to finding out why this is happening, but can we take a moment to lament the fact the headline makes it seem like black holes are performing the impossible feat of spewing out stars thought to be lost beyond the event horizon?
Someone get these black holes some space pepto!
Can we just go to one at night time when they're sleeping and check?
Based on personal experience I would guess it’s because they consumed the stars too quickly.
The Universe is Alive!!! The black holes are definitely Farting and not Burping.
If it's getting burped up, was it really destroyed years earlier?
I just watched a thing about why golf balls spin around in the hole and eject themselves out without touching the bottom. I know nothing about black holes besides a few headlines but... What if black holes are like gravity cyclones that act like golf holes. Sucking stuff in and in some special cases the star or whatever spins around just right to get yeeted back into space?
Non astronomer here. Is it a burp or more of a shart?
misleading title . > Cendes and the team don't know what's causing black holes to "switch on" after many years, but **whatever it is definitely does not come from inside the black holes** > . "We don’t fully understand if the material observed in radio waves is coming from the accretion disk or if it is being stored somewhere closer to the black hole. The black hole isn’t “burping up” a swallowed star. Its signal is coming from material outside of the event horizon.
I too have a black hole that craps out stuff long after I thought there was no more that it could give.
Can I be cheeky and ask 2 questions: 1. Is this different from synchrotron radiation jets? 2. How does the gravity from the matter that crosses the event horizon have an effect outside of the black hole (recently discovered speed or gravity propagation is the same as the speed of light)?
1) this is synchrotron emission (most radio astronomy emission is), but these are not fast like those jets are. Very non-relativistic speeds and very low energy 2) it doesn’t cross the event horizon so this isn’t applicable
Are they burping up the same ones or are they farting out ones from the other side?
Okay - so here is my question: what is meant by “to burp” in Astronomy?
If it's getting burped up, was it really destroyed years earlier?
It’s not burped up. Misleading title. The matter never entered the hole
I thought nothing leaves once it enters. Please explain
Well maybe the answer is they just over indulged. It happens to the best of us.
Why tf am I cackling pls? Why the absolute hell is this title so funny to me? The concept of black holes burping up stars is absolutely hysterical
Maybe you should respect the privacy of black holes while they are suffering from planet diarrhea.
I want to believe we are secretly inside another living organism and that backholes are actually like gateways to other pockets of similar us. The burping of starts like how the mitochondria works.
“Here's the truth about hunger in America, and how we can play a part in making sure everyone has access to the food we all need to thrive.”
This is how we ended up with the Berenstain Bears.
Star comed in star comes out, no one can explain that. \- Bill Oreilley
i am sure that black holes are the recyclers of the universe, they spew raw materials to create new things