Ep. 781: Awakening Black Holes

Oh

Astronomy cast episode 7-81 when black holes weaken. Welcome to Astronomy cast, our weekly

facts based journey to the cosmos will help you understand not only what we know but how we know what we

know. I'm Christopher Kane. I'm the publisher of the universe today with me as always is Dr. Pamela

Gay. I seen your scientist for the planetary sciences do and the director of CosmQuest.

Hey Pamela, how you doing? I am cold. This winter? Yeah. Like it's so cold that even the squirrels

are struggling with the ice. I saw a squirrel fall out of the tree yesterday. It was the funniest

thing. There's this plop in the snow and in the walk of shame. Or it jumped it, you know, it was

new. There was no jump involved. Yeah. So yeah, how are you doing with this winter

arcticness? Warm. Are you kidding? We haven't. We've barely seen below freezing. We're having

10 Celsius days right now here in Western Canada. Yeah, we're minus 10 Celsius. Yeah. I could

be growing oranges. I could have orange trees. We are truly the Florida of Canada at this point.

But I want to shout out and encourage people to check out something that you do, Pamela,

and I gave you a shout out in my most recent space bites. And I'm going to do it again here now,

which is that, you know, for those of you think that Pamela is merely a PhD astronomer who runs

the very successful Cosmic West and is a wonderful narrator. She is also a very

established and skilled news presenter. And that is because she does a weekly show called Escape

Velocity Space News on the Cosmic West channel on Twitch or I don't know where you do this. It's

all told YouTube. Yeah. And it's so good. And you're writing it and you're presenting it and

you're putting up graphics and you know what you're talking about. And so as we live in this world

with so much AI Slop filling the channels and people looking for genuine human voices,

don't forget Pamela. And of course, you know, people tell me all the time, I'll listen to voice,

I go to sleep. I think that's bananas because I be quickly. I rise. Sometimes I'm yelling at you,

sometimes I'm very quiet. I'm very manic. Pamela has this beautiful dulcet tones that just will

help you go to sleep if that's what you require. And so check out Escape Velocity Space News.

Thank you. One long standing mystery in astronomy with a quasars incomprehensible energy blasting

out of a point like source billions of light years away. We now know these are actively feeding

supermassive black holes which can turn off and on in a startlingly short period of time.

Today, when black holes awaken. And we'll talk about a second, but it's time for a break.

Ryan Reynolds here from Mint Mobile. With a message for everyone paying big wireless

way too much, please for the love of everything goodness world stop. With Mint, you can get premium

wireless for just $15 a month. Of course, if you enjoy overpay no judgments, but that's weird.

Okay, one judgment. Anyway, give it a try at mintmobile.com slash switch.

Up front payment of $45 for three month plan equivalent to $15 per month required.

Intro rate first three months only. Then full price plan options available. Taxes and fees extra.

See full terms at mintmobile.com. And we are back. Pamela, let's talk about quasars first because

man, I always enjoy this. If you go and watch Cosmos, the original one with Carl Sagan,

there's right at the very beginning. He is saying there are these things called quasars and we

don't know what they are. And maybe there are messages being I'm not going to do a Carl Sagan

for sure. For sure. But you know, that maybe these are communications being sent by an advanced

civilization in our direction. And maybe these are black holes that are consuming material. Turns out

it was the latter. Yeah. So what are quasars? Just give people speed. It has been amazing to watch

the evolution information about this. When I was an undergrad, we were still using overhead

projectors with like this plasticky stuff that people would hand draw and people would draw

spiral galaxies with monsters in the center. Here be dragons. And it was just awesome.

And the way they were discovered is these point sources were found in images that looked like stars.

But when spectra were taken of them, they're like, what the none of these lines make sense. And

I forget who it was specifically. Sorry, it was not prepared for this specific question.

There was one guy who looked at it and was like, that's red shifted a lot and was able to

identify these were high red shift objects, not individual stars. These were galaxies, but

they looked like stars. How was that? It was deeply confusing. Right. And over the

literally decades, we have gotten better and better equipment. And the first thing they realized

was these are mostly spiral galaxies that have in their core significantly more light being

emitted than in the entire rest of the galaxy. Yes. And and then we had to figure out how

and over time is realized. Okay, so this is an extremely small region in the center that is

massively gravitationally strong. And there is a disc of material around this that is extraordinarily

bright because it's so compact that nuclear reactions are occurring in the disc. Yes.

And over time, it's we started to also put together this unified idea that depending on the viewing

angle, we are able to see different kinds of lines depending on where we're looking in the

desk. Right. And then finally, it was actually my graduate advisor, John Cormady and the team he

was on, they were able to get spectra of the stars around the core of nearby galaxies and see in

red shifts of this material that the only way to explain the motions close in was if it was a

supermassive black hole in the center. Incredible. And you know, the the process of determining

that there is a supermassive black hole at the heart of galaxies has become very mainstream.

You've gotten very good at it. The best tool really is X-rays. So they will use telescopes like

Chandra. They'll be able to detect the presence of X-rays coming from the center of a galaxy and

then use that to locate the position of the supermassive black hole. Some of them are active. Others

are quiet. And so the natural question is, what makes them go from why when they're active,

yeah, what's going on? And then what makes them go from active to quiet? Are there just black holes

that are always active and always putting out material and are there black holes that are always

quiet? Was the supermassive black hole the heart of the Milky Way once active? We have questions

Pamela, answer them in whatever you wish. Okay, so yes, our black hole has been active in the past

when we look at the core of the galaxy and the surroundings in X-rays and infrared were able to

see bubbles of material that was pushed out by the massive light pressure of some sort of a

disc that was around it in the past. We see these bubbles, we see these high energy particles that

are relics of past activity. We don't see relics of jets associated with our galaxies, whatever

occurred appears to have been short term, wasn't highly active. But these kinds of activities that we

see early in the universe in large numbers and in decreasing numbers as the universe ages appear

to be driven by some sort of an interaction between multiple galaxies that drives material dust,

gas, stars into the core where they get gravitationally locked into a death spiral with the supermassive

black hole. And because of conservation of angular momentum, which is the enemy of all activities

in astrophysics as near as I can tell, as this material spirals in towards the core of the supermassive

black hole, the core of the galaxy rather, you end up with a disc building up, things keyed up in

the disc, that disc and its light is what causes the quasar, it's not. It's on the black hole.

Yes. It's the stuff trying to drop enough angular momentum to fall into that black hole.

And the magnetic fields that are surrounding the black hole and its interactions.

Those channel jets, yeah. That channel the jets and when you're staring down the barrel of the

jet, then you see a very bright center to the galaxy called a blazer. But so that is sort of the

explanation. And so then, actually, I want to take a break because of the question I want to ask

you is, are they forever? And when I ask you that question and you clearly left that one to the

end, but we're going to get to that in a second, but it's time for that second break.

And we're back. So are actively feeding galaxies always actively feeding or they're not sometimes?

It turns out that they either run out of food naturally or fling their food away.

So actively feeding black holes, active galactic nuclei, quasars is what we call them when

they're sufficiently bright. That accretion disc generates a whole lot of light. And if it generates

enough light, the pressure can start pushing away material that would want to be falling in.

This sounds like the Eddington limit. Yeah. So there's two different ways that black holes stop

feeding. One is there's just not enough stuff. They run out of stuff to eat. I mean, we've all been

there. You open the refrigerator door and realize mistakes were made. So it turns out, yeah, they can

just run out of food sometimes. The other issue is they can have a disc that is so thick, so bright.

It starts pushing material away. It clears the region around it. And it goes hungry until the next

time. Right. Some sort of interaction occurs. And what's so cool is we are starting to find

these intermittent jets where you see dashed lines in the radio jets coming out of these

systems. Oh, that's correct. Yeah. It's where they turned off and turned on. And you can actually

see how long they were off and how long they were wrong. Exactly. Exactly. Yeah. And we had previously

seen examples of quazers turning off. Hennie's Vorvarp is an example of that. But the fact that

we're now finding these dashed jets of systems that turned on and off is just kind of awesome.

And I have to say, black holes at every scale are equally likely to do this kind of stuff.

Stellar black holes and binary systems will steal material off of their companion,

create accretion discs that light up, form jets. And when that companion either evolves to a

different stage or just runs out of food in the gravitational Rochelo limit, that feeding will

turn off. And so there are cataclysmic variables that include black holes out there doing their

black hole things that Stellar mass size. Yeah. Yeah. Exactly. There's this really interesting

correlation that you can actually study relatively close to us micro quazars. You know, I say tiny

black holes nearly with five times the mass of the sun, right? That are a creating material from

some partner and are have built an accretion disc and are firing out jets and they are in

surprisingly similar ways, identical in terms of behavior to the ones where you've got a billion

times the mass of the sun and can be used to study this for something that is much, much closer to

home. Yeah. The laws of physics don't care what scale it's at. Yes. Yeah. Which is kind of

surprising because you think there'd be a certain, you know, something would compound as these

things get a lot more massive, but, but it all sort of works at different scales perfectly.

So then, you know, you mentioned that you see this dotted line. Yeah. How quickly does it appear

that black holes can shut off and can shut on again? It's millions of years. So it's hard to tell

exactly how long it takes them to turn off and turn back on. What we see is gaps and the example

that is most recent is J1007 plus 3540. And it turned off as narrow as we can tell for about

a hundred million years and then turn back on. And we see that from the gap in its jet and we can

see evidence in the jet of prior intermittency. And what's amazing is this is a system that's

in a very thick galaxy cluster. And so its poor jet is beat to, yeah. It's beat up by interacting

with the surrounding intergalactic media or inter cluster media as the case may be. Yeah. Radio is

starting to reveal some really cool stuff. The longer we have these high resolution systems like

Glowfar and the new system in India online, the more of these kinds of things we're going to

discover. So I think you might be wrong about the millions of years. Like I think the period

is faster than that in some cases that people are seeing these things. They turn on and off much

faster. But the gap in time that this right right off. Yeah. Yeah. So that's the so the turn off

and turn on. So they turn on and off fairly quickly. We don't know exactly how quickly.

But they can have gaps in time that are hundreds of millions of years. Yeah. Yeah. And I think

you know like part of this is that you know as you said you have that this accretion disc that's

around the black hole. But there's there's this idea that it's actually really hard for material

to kind of make that final drop down into the into the black hole. We've got to shed all that

final angular momentum. And that it can just happily be spiraling around the black hole for longer

periods of time before bits and blobs of it are being thrown in. And sometimes it requires

some external interaction. Another a new gas cloud giving. Exactly.

Star that causes turbulence that then throws in a new thing. And so so I think you know apparently

we've seen quasars where they've noticeably brightened in the kinds of time scales that we

can understand like within a decade within a couple of years within. You can see periodicities

in their prices over days. Yes. Over days. Yeah. So it's quite common to see that.

Yeah. And so I think what was thought was well here's a thing that that's black hole is digesting

whatever a thousand solar masses of material that it is piled up around it. And that's going to

take 10 million years to do. No. You're seeing variations that are happening on within human lifetimes.

And what's really cool is you can actually map out the accretion disc region by looking at the

timescales of variations because the timescale the shortest possible timescale is dictated by

how big or how small the area that's emitting light will be because you have to wait for the light

from the entire object to reach you. And so the short of the variations we see the smaller the

scale of the structure that's doing that. And so when we see these variations it's a variation

in the rate of consumption that the black hole. We haven't yet caught a black hole going

entirely from active to completely turned off. And so we've only seen these variations in eating.

And we've seen cases of like something gets nommed. But it was a quiet black hole that just suddenly

ate something. So it burped. And we've even seen it with the supermass of black hole at the

Milky Way that there are. There's a couple of masses worth of the earth going into the black hole

every year. Periodically. And so you'll get sort of a constant blast of x-rays and various radiation

coming from the center of the Milky Way. And occasionally you get a little more. We're going to

talk about the consequences of this in a second but it is time for another break.

And we're back. So you hinted at this early on in the episode that that these jets, this activity

has consequences for the galaxy that it is inside. And around it. And around it. Yeah like reaching out

to other galaxies potentially within the cluster that it's forming in. So so how does a actively

feeding supermass of black hole in the jets and the material that it produces. How does that

cause mayhem around it both in the galaxy and nearby. So when this is occurring in a cluster

environment, we have seen one case of a jet spearing a nearby galaxy and deforming it. So these

jets are carrying energy. They are carrying momentum. They can push stuff around. Yeah. And what's

amazing is as we look at more and more radio lobes, we can see them essentially forming fountain

like ends as they interact with the significantly denser intra cluster media. So they're pushing out

on the media creating dense places. And when what they actually hit is another galaxy, they can

trigger star formation. Or snuff it out. Or kill it. Yeah. That's possible too. They can just push out

the material that would form stars. Yeah, these jets. I can people didn't understand. These jets

are last are going out. Tens of thousands, if not hundreds of thousands of light years long,

the material blasting out of these jets is going at relativistic velocity. Yeah. 10% of the speed

of light, 20% of the speed of light. Like this is serious business. And if you get caught,

if your galaxy gets caught in the death beam of another galaxy's actively feeding black hole,

shenanigans ensue. And this is all a story of interactions. Quasars are created by having

large amounts of material somehow triggered to fall into the center of a galaxy, which is most

likely to occur when you look at these, the most common reason this happens is two galaxies

interacted. The galaxies are merging. And then you have the jets are going out and getting stabby

with other galaxies with the surrounding interstellar media. It is all a story of galaxies.

I mean, we have all sorts of words that's called galaxy harassment when they pass by each of

the two clothes. It's where I'm pressure stripping when the inter cluster media decides to

push material out of a galaxy. Quasars are often related with massive amounts of star formation

that's going on as dust and gas are getting compressed. And once all of this chaos comes to an end,

you're often left with a red dead galaxy. Right. So you essentially are force feeding a galaxy

its own gas. You're causing all of its stars to form at once, burn through its reserves of gas,

and now it's out. It's done. Now it's dead. Yeah. And then all of the the red

all the stars just commonly evolve. Yeah. The blue ones go away supernova style as they do

and tell this galaxy eat something else. Right. And then you know, it has fresh gas. And then it

all starts over. Yeah. But, but you know, this is the effect that perhaps it can have on other

galaxies. What what even effect can this have on the galaxy that the black hole is is within?

Well, I mean, it's deforming it by using its light to push things out. It is interacting with

its media by pushing that around. It's it's all a story of getting pushy for lack of better

phrase. I mean, I think that I that I find kind of interesting is that you get this almost like

a fountain in some cases. So the material is being blasted out, but then the gravity of the galaxy

is dragging it back down. And so it's it's sort of raining back down into the galaxy. That's the

innermost scale. We see this not in radio. This is something you study. Yeah. Yeah. Yeah. And

that this could be seeding the galaxy with elements with fresh material with shock waves that are

causing star systems, you know, causing gas caused to collapse and begin the process of star

formation. And that that you get nucleosynthesis, you actually have heavier elements being formed

in these accretion disks around the black holes. They're like stars. And then the material is

being siphoned out of the accretion disk jammed into the jets and then pounding back down across

the galaxy itself enriching it with carbon nitrogen oxygen. Yeah. And so like could we depend on

a supermassive black hole for life? Oh, man. I wouldn't depend on it. No, but it's definitely

a component. It's a component. And and as we look out across the interstellar media, we find really

complex molecules. And these clouds of material have to get enriched somehow. And when you see them

enriched supernovae would deform them, would shock them. And so this is a gentler way in a way to

enrich the outer parts of the galaxy with material without causing the clouds of material to collapse.

Right. Right. So there's one last thing that I wanted to talk about. I don't know whether it

seems to be a show on its own. And I don't know if this is in your mind, which is these transient,

oh man, transient, luminance events. Yeah. Yes. Those are cool. And yeah. And we need to do a show.

And I'm working on any of you who are on Patreon, drop me your ideas. I'm working and putting together

the schedule for the rest of the season. Yes. There's a bunch of things that just like go flare in

the night that we need to do a roundup of as as we're starting to get more and more understanding.

Let's go into this anyway. We'll talk briefly about these about these because they're related to

the brightening of galaxies and and accretion disk and so on. But essentially, we now know that

supermassive black holes can have other black holes in orbit around them. And as those black holes

are passing through the accretion disk plunging through the accretion disk, you get a flash coming out

of the the center of the galaxy. And and so this flash is not the central supermassive black hole.

It's some other high density object, whether it be an intermediate black hole or whatever.

It just got hungry and stole food from its friends. Right. And and eventually that's going to lead

to emerging black hole. We're just not seeing those yet. We need more gravity wave detectors.

And it's really impressive. Like there's this flash. You get the x-rays. You get the visual

confirmation. And there's this periodicity where the astronomers are able to say, oh, it it went

up through one part of the disk. And now it's come back down through the other part of the disk.

And we're expecting to see it flash again in precisely 18 months. And then right on schedule,

flash, as this black hole is is passing through the accretion disk of another black hole.

And what I love is because the supermassive black hole has such huge mass, we can on human

timescales see things orbiting it, including other black holes. And and we've been seeing this

with Andrea Getzwork looking at the core of the Milky Way, watching stars and blobs of gas orbit

around over decades. This is this is astronomy and human timescales. This is the kind of thing that

very rarely happens. And it's really cool to get to see it with high energy events that

get all the telescopes involved. Yeah, yeah, absolutely. And it really is interesting to me

how I mean, I hate to use this sort of anthropomorphization analogy that it's all about the village,

that that no black hole is an island, that black holes evolve in galaxies. The galaxies are part

of galaxy clusters and and that things that happen in one galaxy can reach out across millions

of light years to the other galaxies that are around it and have an influence on it. And so one

bad apple can spoil the planet. I'll just keep making analogies here. But the point is that

is that what you might have in terms of like save the potential for life in your galaxy depends on

what was the environment of the galaxies around your galaxy where they all sort of

feasting on material, blasting out jets. Was it like you're trying to exist within all these

death rays and you ended up in a red dead galaxy or were you far enough away that that didn't happen

or that there was a near miss that just enriched the galaxy with the heavier elements that are

required for life, but not the death beam that that caused it to die too young too early. And this

is the kinds of stories that astronomers are still trying to pick apart. It absolutely plays a

role, but we don't know what role exactly it. And what's so cool is I was so disenchanted with J.A.D.A.S.T.

before it lodged because so much money and so many careers had been ended because their money was

stolen for it. I'm still bitter, but it is living up to its potential. And

we are starting to be able to see in the early universe the way galaxies were clearing out the

space around them using these jets. And there's some really cool illustrations that are out there

of this that end up looking like cells because you have these galaxies moving through the material

around them. I'm really enjoying watching the evolution in how people are trying to understand

the little red dots. There's a couple of competing theories that have come out recently. The one

that I like the best is that the very first stars, like all sets of stars, had an initial mass

function where some of these stars were so big that they collapsed directly to intermediate black holes.

And it is those massive, massive stars and their surroundings that led to these little red dots.

My hope is that we're seeing the formation of globular clusters. Okay. That's my hope. Yeah,

that's another one of the theories. Because they're so compact and tight. And yet we're like

where the globular clusters are as old as the universe. Where did they come from? So are they

the stripped cores of dwarf galaxies or are they a separate thing that formed and then found their

way into other galaxies? That's my hope. That's direct collapse would be incredible. Like we're

literally seeing the direct collapse of black holes because they're gone within. But we did

a whole episode on little red dots. Didn't we? Yeah. Yeah. Yeah. We don't need to rehash that.

Awesome. But that was super fun. Thanks, Pemble. Thank you, Fraser. And thank you to all of you

who support us through Patreon. You make it possible first to do all the things we do and have other

people help us. So yeah, this week I would like to thank the following people.

This week I'd like to thank the following $10 a month and up patrons. Abraham Catrell, Alex Cohen,

Andrew Allen, Andy Moore, Arno DeGroote, Bore Andro Levesval, Benjamin Carrier, Bill Smith,

Boogie Nut, Brian Breed, Brian Kilby, Buzz Parsec, Claudia Mastriani, Cooper, Daniel Shecter,

David Gates, Diane Philippon, Don Mundis, Ed, Eric Lee, Father Prax, Frederic Salvo, G. Calib

Sexton, Gerhard Schweitzer, Gold, Greg Viled, Hannah Takary, Jacob Hool, Jarvis Earl,

Jeanette Wink, Jim McGeean, Joanne Mulvey, John Muthus. And thanks, Fraser.

Thanks, Pemble. And we will see you all next week. Bye-bye.

Astronomy Cast is a joint product of Universe Today and the Planetary Science Institute.

Astronomy Cast is released under a Creative Commons Attribution License.

So, love it, share it, and remix it, but please credit it to our hosts, Fraser Kane and Dr.

Pamela Gay. You can get more information on today's show topic on our website, astronomycast.com.

This episode was brought to you thanks to our generous patrons on Patreon.

If you want to help keep this show going, please consider joining our community at patreon.com

slash astronomycast. Not only do you help us pay our producers a fair wage,

you will also get special access to content right in your inbox,

and invites to online events. We are so grateful to all of you who have joined our Patreon

community already. Anyways, keep looking up. This has been Astronomy Cast.