sciencehabit sends us to Sciencemag.org for an account of a survey of nearby galaxies that points to the possibility that once-quiescent galactic nuclei could wake up and become active again. If the Milky Way's dormant black hole should become active, it could be bad news for life on Earth (and elsewhere in the neighborhood). The paper (PDF) is up on the arXiv.
Remember kids, just like government mind control rays the gamma ray bursts generated by our galaxy's black hole center can be blocked by a tin foil hat.
Darn, and I never EVER rtfa, but the summary made it necessary. So for my fellow slashdotters who hate to RTFA, what they mean by "reignite" is to turn into a quasar. The way the black hole could turn into a quasar is for the galaxy to collide with another galaxy.
I don't think we have anything to worry about. Nothing to see here (and if it happened, nobody to see it)
"The way the black hole could turn into a quasar is for the galaxy to collide with another galaxy."
That's not what the article says: It's not understood what is causing the black holes to become newly active, because in most cases there is no evidence of collisions or mergers.
>...what they mean by "reignite" is to turn into a quasar. The way the black hole could > turn into a quasar is for the galaxy to collide with another galaxy.
You didn't RTFA very well. The point is that they have found galaxies whose black holes have reignited without there being any evidence of a collision.
As matter accelerates and gets closer and closer to the event horizon, particles begin bouncing into each other, like outside that one Who concert. Except in this case, instead of being crushed to death (as those concert-goers), centripetal force slings matter towards the poles of the hole with enough energy to achieve escape velocity. This creates a massive beam of ultra-high energy particles that would be very bad for your health. Well, two beams (one "up" and one "down"), but you get the idea.
Never in my life did I think I'd see a concert analogy for black holes that was so close to correct. I applaud you king of absurd but mostly truthful analogies!
Unfortunately, your lack of practice in reading articles is apparent in your attempted explanation. I am no expert on the subject matter, but even I know enough to recognize that you misunderstood what they are saying.
Actually, the main message I get from the article is how complex the universe is, and how little is known, even by the most knowledgeable, about how these mechanisms work.
For a black hole to be active, it needs stuff falling into it...gas, dust, stars if you're unlucky. The stuff heats up to an extraordinary temperature due to friction as it falls in. To be hazardous at our distance of 25,000 light-years from the galactic center, it has to be quite a bit of matter falling in for a harmful intensity of radiation.
Our galaxy's black hole, Sagittarius-A, is not considered active, although it does have some weak emissions, primarily at harmless infrared and radio wavelengths consistent with a very small accretion disc. The nearest star to the black hole is estimated to be about 70 times as far away from it as it would need to be for the gravitational forces to remove significant amounts of material from the star. It also has an orbital period of 15 years, so it would take a long time and a significant perturbance to fall significantly close. It doesn't seem likely at all that it would become active in the foreseeable future.
Darn, and I never EVER rtfa, but the summary made it necessary. So for my fellow slashdotters who hate to RTFA, what they mean by "reignite" is to turn into a quasar. The way the black hole could turn into a quasar is for the galaxy to collide with another galaxy.
I don't think we have anything to worry about. Nothing to see here (and if it happened, nobody to see it)
Obviously there is something to see here. Us. Our sun was a member of a galaxy that was absorbed by the Milky Way. The evidence is in the fact that we do not orbit the center of this galaxy in the plane of its arms, but rather perform a wave-like motion alternatively above and below the center plane, passing through the plane in between peaks. A galactic collision could produce the effect noted in TFA, while simultaneously increasing interstellar gas and dust cloud densities, protecting the outer stars fro
So massive core explosions delivering a huge radiation wave are expected.
Step 1:
- invent scrith
Step 2:
- build Ringworld
Step 3:
- profit (sell real estate)
Dear Sir and/or Madam:
Good Day. My name is Jack Brennan. You may call me Brennan-monster. I am writing on behalf of my Protector brethern. This letter constitutes a cease and desist notice. You have been publishing our trade secret, that is, our business plan. Please remove said plan from you website at once or face litigation.
I always figured such a move to be more like, "I sense you are a threat and will now destroy your entire lineage. With my bare hands." rather than a C&D letter on paper
Umm... Jack Brennan (AKA BrennanMonster) was trying to protect humanity from the Pak, and the Pak already made the Ringworld, so prior art, and all that...:)
but it is intriguing. I'm always impressed when scientists come forward and admit that they've found something they didn't expect. It validates the scientific method and the people who apply it to research - whether it be mathematics, anthropology, physics, cosmology, . . .
SO - not unlike the assertion (for example) that there's a large asteroid with Earth's name on it, this research seems to indicate that perhaps we should start studying this phenomenon now even if there's nothing we can do about it now. After all, much of our modern technology was understood to be impossible/impractical as little as a century ago; if we start looking now, perhaps we can devise a mechanism for the preservation of our species before we need it. Then again, when has humanity ever shown that much foresight?
Understanding something better could have a big reward. Maybe not avoiding that all the life in 30k light years from galaxy center is wiped out, of course (that is the core of the RTFA?), but think that that will not happen (soon, at least), and that we learn more... maybe we can use that to implement future technologies or even stop a very dangerous experiment at LHC.
You DO know that particles with much higher velocities and energy levels than the LHC could ever produce interact with other particles every second in the upper atmosphere of Earth
You DO know that such collisions involve one particle with high velocity impacting a particle at rest (relatively speaking) with respect to the earth, making the collision products scatter like billiard balls after a good break and thus taking them away from the planet in short order? As opposed to colliding two streams with o
...the collision products scatter like billiard balls after a good break and thus taking them away from the planet in short order?
It seems to me that a significant fraction of the collisions would produce particle showers pointed towards the ground. Even if 99% of the "evil bits" have momenta that don't allow them to settle into the earth, there's still a lot of evil bits (produced by incident particles with energies 10^4-10^6 times more energy than the LHC) over the last 4+ billion years that haven't des
From TFA it seems like somewhere between 20-40% of galaxies surveyed have active nuclei, but how do they know they reignited?
It's not understood what is causing the black holes to become newly active, because in most cases there is no evidence of collisions or mergers.
How could it be verified that despite the lack of a recent collision with another galaxy, these particular phenomenon were at some point dormant like ours, then reignited? How are they supporting this claim that these galactic nuclei must have spontaneously rekindled vs. they have been winding down from a collision very far in the past?
There's just one problem: Astronomers have found quasarlike centers--called active galactic nuclei (AGN)--in some relatively nearby galaxies, which should be far too old to generate such energies.
So they should be too old for this sort of behavior, but how are they verifying the time since the last collision? Another possibility is that these galaxies had a collision more recently right?
How could it be verified that despite the lack of a recent collision with another galaxy, these particular phenomenon were at some point dormant like ours, then reignited?
By the velocity vectors of surrounding matter affected by the blast? A collision would give the local matter directionality whereas a spontaneous reignition would send matter out in all directions uniformly.
Haven't you watched CSI: Stellar Cartography Unit?
OK, so I've R'd TFA, and I've read what people have posted so far. But, I'm still too thick to get it. So, a quasar is an energetic black hole? Or it's kinda like a black hole, but different, and with more spinning and less dark?
What is the black hole "doing" when it's not spraying high energy particles every where? What happens to turn a black hole into a quasar short of two colliding galaxies? We're now sure that there is a black hole in the center of all-if-not-most galaxies seems to be implied by thi
Quasars are an effect created by the supermassive black holes at the centre of each galaxy, these black holes consume tremendous amounts of mater (something like 10 sun masses a year) the more solar masses they consume the brighter they are. Obviously there is only so much material than can be pulled in by the supermassive black hole, eventually all the material is either ejected as high intensity engery (the quaser pulses we can observe) or consumed by the black hole.
Quick summary of TFA:
Scientists observe that the black holes at the center of galaxies were Quasars on far away galaxies. The one at the center of the Milky Way and other nerby galaxies were observed to not be Quasars. So they theorised that the black holes initially are quasars after galaxy formation, and they run out of fuel. New observations show that nearby galaxies do in fact have quasars. A scientist conjectured that it re-ignited. Better conjecture may be that the fuel source of those blackhole-quasars is more variable than previously thought.
That would be the most likely mechanism for reignition.
Black hole eats everything in easy reach, goes dormant. New source of fuel builds up in the neighborhood, black hole starts eating again, and the galaxy "reignites".
We detect the presence of black holes at galactic centers by observing the stars whirling around said galactic center at high rates of speed, right? All those stars whirling around have mass, therefore, gravity. Other stars moving around, maybe not as near to the galactic center, also have gravity. All this movement and such may attract, due to gravitational pull, a cloud of gas somewhere nearby. Slowly it gets pulled by the stars' gravity, until it gets into the gravitational pull of the black hole. Quasar'd!
Sure, it may seem academic now, but in just 3e9 years, our galaxy is going to merge with the Andromeda galaxy(http://en.wikipedia.org/wiki/Andromeda-Milky_Way_collision [wikipedia.org]). That would re-ignite re-ignite the merged black holes, and we'd have to move to a better neighborhood.
Nope. That's entirely speculation. We do not know the transverse velocity of the Andromeda galaxy, only the velocity along the line of sight. No way to tell if it's going to hit or not.
It seems like I read a sci-fi short story along these lines. Only I don't think it was a "black hole reignition". It was a "sun-like" object, only on a much larger scale. Scientists had verified it's existence and determined that, coincidentally, the first light from that object would soon reach earth (I don't know how they discovered it before the light from it reached us, but that's beside the point). Anyway, everyone's watching waiting to see this amazing new thing when it appears... and it burns ev
Protect yourself (Score:5, Funny)
You may want a tin foil codpiece, too.
oblig. (Score:3, Funny)
Re:oblig. (Score:5, Funny)
Parent
Eye muss bee knew hear (Score:4, Informative)
I don't think we have anything to worry about. Nothing to see here (and if it happened, nobody to see it)
Re:Eye muss bee knew hear (Score:5, Informative)
That's not what the article says:
It's not understood what is causing the black holes to become newly active, because in most cases there is no evidence of collisions or mergers.
Parent
It's not just definite, it's *in*definite. (Score:2)
Re: (Score:3, Insightful)
> turn into a quasar is for the galaxy to collide with another galaxy.
You didn't RTFA very well. The point is that they have found galaxies whose black holes have reignited without there being any evidence of a collision.
Re:Eye muss bee knew hear (Score:5, Interesting)
As matter accelerates and gets closer and closer to the event horizon, particles begin bouncing into each other, like outside that one Who concert. Except in this case, instead of being crushed to death (as those concert-goers), centripetal force slings matter towards the poles of the hole with enough energy to achieve escape velocity. This creates a massive beam of ultra-high energy particles that would be very bad for your health. Well, two beams (one "up" and one "down"), but you get the idea.
Parent
Soo close (Score:2)
Re:Eye muss bee knew hear (Score:5, Funny)
It isn't a galactic collision. It's just the reunion tour for Disaster Area.
Parent
Speaking as user Slartibartfast... (Score:2)
Reading comprehension requires practice (Score:2)
Actually, the main message I get from the article is how complex the universe is, and how little is known, even by the most knowledgeable, about how these mechanisms work.
Re: (Score:2)
Re:Eye muss bee knew hear (Score:4, Funny)
Parent
Feed Me (Score:4, Informative)
Our galaxy's black hole, Sagittarius-A, is not considered active, although it does have some weak emissions, primarily at harmless infrared and radio wavelengths consistent with a very small accretion disc. The nearest star to the black hole is estimated to be about 70 times as far away from it as it would need to be for the gravitational forces to remove significant amounts of material from the star. It also has an orbital period of 15 years, so it would take a long time and a significant perturbance to fall significantly close. It doesn't seem likely at all that it would become active in the foreseeable future.
Parent
Re: (Score:3, Informative)
Darn, and I never EVER rtfa, but the summary made it necessary. So for my fellow slashdotters who hate to RTFA, what they mean by "reignite" is to turn into a quasar. The way the black hole could turn into a quasar is for the galaxy to collide with another galaxy.
I don't think we have anything to worry about. Nothing to see here (and if it happened, nobody to see it)
Obviously there is something to see here. Us. Our sun was a member of a galaxy that was absorbed by the Milky Way. The evidence is in the fact that we do not orbit the center of this galaxy in the plane of its arms, but rather perform a wave-like motion alternatively above and below the center plane, passing through the plane in between peaks. A galactic collision could produce the effect noted in TFA, while simultaneously increasing interstellar gas and dust cloud densities, protecting the outer stars fro
I am building a ringworld (Score:4, Funny)
Step 1:
- invent scrith
Step 2:
- build Ringworld
Step 3:
- profit (sell real estate)
Re: (Score:3, Interesting)
So massive core explosions delivering a huge radiation wave are expected. Step 1: - invent scrith Step 2: - build Ringworld Step 3: - profit (sell real estate)
Dear Sir and/or Madam:
Good Day. My name is Jack Brennan. You may call me Brennan-monster. I am writing on behalf of my Protector brethern. This letter constitutes a cease and desist notice. You have been publishing our trade secret, that is, our business plan. Please remove said plan from you website at once or face litigation.
Sincerely yours, Jack Brennan
Re: (Score:2)
Re: (Score:3, Funny)
I am civilised, after all. I'm a Belter, not a lawyer.
Jack Brennan.
Re: (Score:2, Interesting)
Okay, so this isn't relevant to my day-to-day life (Score:3, Insightful)
SO - not unlike the assertion (for example) that there's a large asteroid with Earth's name on it, this research seems to indicate that perhaps we should start studying this phenomenon now even if there's nothing we can do about it now. After all, much of our modern technology was understood to be impossible/impractical as little as a century ago; if we start looking now, perhaps we can devise a mechanism for the preservation of our species before we need it. Then again, when has humanity ever shown that much foresight?
Re:Okay, so this isn't relevant to my day-to-day l (Score:2)
Re: (Score:2, Interesting)
You DO know that such collisions involve one particle with high velocity impacting a particle at rest (relatively speaking) with respect to the earth, making the collision products scatter like billiard balls after a good break and thus taking them away from the planet in short order? As opposed to colliding two streams with o
Re: (Score:3, Interesting)
It seems to me that a significant fraction of the collisions would produce particle showers pointed towards the ground. Even if 99% of the "evil bits" have momenta that don't allow them to settle into the earth, there's still a lot of evil bits (produced by incident particles with energies 10^4-10^6 times more energy than the LHC) over the last 4+ billion years that haven't des
Oh noes! (Score:2, Funny)
Quick, invade something, anything!
Re: (Score:2)
20 to 40%? Reignite? (Score:5, Insightful)
Re:20 to 40%? Reignite? (Score:4, Informative)
Haven't you watched CSI: Stellar Cartography Unit?
Parent
The galactic core could be exploding? (Score:5, Funny)
Still not getting it ... (Score:2)
So, a quasar is an energetic black hole? Or it's kinda like a black hole, but different, and with more spinning and less dark?
What is the black hole "doing" when it's not spraying high energy particles every where? What happens to turn a black hole into a quasar short of two colliding galaxies? We're now sure that there is a black hole in the center of all-if-not-most galaxies seems to be implied by thi
Re: (Score:3, Informative)
Quasars are an effect created by the supermassive black holes at the centre of each galaxy, these black holes consume tremendous amounts of mater (something like 10 sun masses a year) the more solar masses they consume the brighter they are. Obviously there is only so much material than can be pulled in by the supermassive black hole, eventually all the material is either ejected as high intensity engery (the quaser pulses we can observe) or consumed by the black hole.
The scary part (Score:2)
The night sky would be pretty though.
maybe it already has (Score:3, Insightful)
Re: (Score:3, Insightful)
No evidence for "re-ignition" (Score:4, Informative)
Re: (Score:2)
Black hole eats everything in easy reach, goes dormant. New source of fuel builds up in the neighborhood, black hole starts eating again, and the galaxy "reignites".
Axis of Rotation (Score:2, Interesting)
Re: (Score:3, Interesting)
Re: (Score:2, Informative)
Space as we know it.. (Score:2)
Here's a theory (Score:3)
We detect the presence of black holes at galactic centers by observing the stars whirling around said galactic center at high rates of speed, right? All those stars whirling around have mass, therefore, gravity. Other stars moving around, maybe not as near to the galactic center, also have gravity. All this movement and such may attract, due to gravitational pull, a cloud of gas somewhere nearby. Slowly it gets pulled by the stars' gravity, until it gets into the gravitational pull of the black hole. Quasar'd!
Just you wait... (Score:2)
Re: (Score:2)
Nope. That's entirely speculation. We do not know the transverse velocity of the Andromeda galaxy, only the velocity along the line of sight. No way to tell if it's going to hit or not.
What to do? (Score:2)
stranger than fiction? (Score:2)
It seems like I read a sci-fi short story along these lines. Only I don't think it was a "black hole reignition". It was a "sun-like" object, only on a much larger scale. Scientists had verified it's existence and determined that, coincidentally, the first light from that object would soon reach earth (I don't know how they discovered it before the light from it reached us, but that's beside the point). Anyway, everyone's watching waiting to see this amazing new thing when it appears ... and it burns ev
The ORI are coming and need the black hole to powe (Score:2)
Re: (Score:2)
And it may have already happened, so go ahead and have that extra dessert.
-science nerd, dessert lover
Wrong. We are ~26,000 LYs from the galactic core. (Score:2)
Re: (Score:2)