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Space Science

Black Holes May Promote Stellar Birth 36

Posted by timothy
from the breathe-honey-breathe dept.
Porfiry writes: "The unusually high rates of star births seen in some galaxies may be linked to voracious black holes at the center of those galaxies, according to a new analysis of astronomical data by researchers at Johns Hopkins University. The new results suggest that galaxies with rapid rates of star formation and galaxies with active black holes, long considered separate phenomena, are actually links in a single set of evolutionary processes that shape the development of galaxies."
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Black Holes May Promote Stellar Birth

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  • As anyone know, black hole loose particle, and become more and more small, and at one time will have a 0 mass (i think it's Stephen Hawking that said that in the 80s).
    Because of the incertitude principle (quantic mechanic), a pair of particle/anti-particle can be created at the horizon (frontier) of the black hole, one of those fall in the black hole, the other can get away, and black hole loose mass. It's not the same particle that entered the black hole that get out of the black hole, i don't know really what happen to the particle into the black hole when it reaches 0 mass? anyway...
    Stars can use what get out of the black hole i guess.
    --
  • When are we going to get to the stage when we can actually launch human-piloted (or not) craft and physically go out and explore these things and prove them right or wrong?

    I see you fail to grasp the size of even the local universe. Galaxies are FAR away. Not as in 'it-must-be-expensive-to-get-there' away. I mean 'it-takes-multiple-millions-of-years-at-the-speed- of-light' away. For several (non-technical but rather physical) reasons it is impossible for humans to travel at more than a fraction of c. Please factor in above.


  • Thats right, black holes dont exist.. at least, not in the way the movie depicted 'em. My high-school physics teacher (4 years ago) explained to me a different theory: in the universe a lot of solar systems actually have 2 suns. They orbit each other in strict mathematical fashion known as a 'Binary Dance'.. so late one night, a pair of astronomers notices a giant doing the Binary Dance all by itself. In fact, it was doing it at incredible speeds! Like that which a dwarf star might do around a giant. Obviously there had to be something there, so they kept searching. Eventually they found it: a black hole.. but that only increased their confusion. Why was a giant star orbiting a black hole? Aparently, it has some properties of a star.. and a very large star (at least in gravitational pull) at that. Meanwhile, on the other side of the world, someone else finds out that if you happen to look at a black hole with the right filter on.. ITS NOT REALLY BLACK! Apparently, black holes do emit light.. forget what type of radiation most of it is, but it starts with a 'k'? Anyhow, while it does pull much light into itself, it also releases a much greater amount of light in this different form of radiation. One that scientists havent been looking at apparently. So, final conclusion: Black Holes are really massive stars that emit mostly one kind of radiation, which unless you look for it, doesnt show up.. making the star look black. Then again, I havent heard much of this theory lately, and people are still using the old definition.. maybe its been disproved. -PZ
  • It'd serve many people well to have a little understanding of the properties of numbers.
    Here are _TWO_ of my favourites:
  • Bah, I've always wondered (and will quite happily continue) wether black holes exist. I mean, Albert himself warned against pulling the beadspread too much... I'm continuously told to make shure the darn model in use isn't stretched too far so I wonder if the same applies here. I mean... I've discovered several "dream devices" only to feel a a dunce hours later...

    BTW, is there a good reason to exclude large scale electromagnetic interaction as current cosmologies do? After all plasmas abound so why assume it's only gravity's fault...
  • Thanks for the link vapour! I have been looking (well, hoping someone would post a link) for a nice web page that described black holes without going too much into the math. For anyone interested, that Jillian's guide is EXCELLENT. While I still don't really understand spacetime diagrams, it did explain everything else very well. And even without really understanding those diagrams, I was still able to understand the topics that relied on them (Singularities, White Holes, Blue Sheets, etc.).

    I can't speak for the other one since I'm at work and they don't allow mpeg's through the firewall, but I do plan to check it out when I get hoem.

  • Now I am by no means an expert in this field, having only just read the above link to Jillian's Guide to Black Holes. However, here's what I got from that page that applies to your post.

    I think the radiation you are referring to is 'Hawking Radiation' or possibly gamma radiation. If its Hawking Radiation, I can only say this, virtual particles are being formed and expelled from the black hole. I won't go into detail on how they are formed, I don't understand it well enough. As for the gamma, this is how I've understood it (and it could be wrong). Imagine a ray of light coming at a tangent to a black hole. As it approaches the black hole, it bends toward it and can eventually go into orbit around it. Yes, I did just say that light can orbit a black hole. This point where light will orbit (potentially forever, but not in reality) is called the photon sphere. Now since other things (light, dust, etc) are passing through, these will eventually disturb the orbit of light. As it starts to fall in, it gains kinetic energy. With any mass, this would present itself as acceleration, however, nothing can go faster than the speed of light. So, instead of speeding up, the light gains more energy and blurs to red, infrared, X-ray, and finally gamma. As it gains this energy, it can also escape the black hole, assuming of course it hasn't crossed the event horizon.

    This can also happen with particles of dust and even electrons. As they speed up, they are giving off more and more energy (they can only go so fast). This energy is expelled in the form of x-rays and gamma rays.

    So, I wouldn't call a black holes
    really massive stars that emit mostly one kind of radiation, which unless you look for it, doesnt show up.. making the star look black
    Again, I'm no expert here, but stars are usually objects that are burning hydrogen and/or helium and releasing energy in various forms of light. Black holes on the other hand, tend to be very very cold, large ones are indistinguishable from 0 degrees Kelvin (absolute zero). Now from what I've read on the subject, the biggest difference between stars and black holes is that black holes have a singularity... which is in essence, the point where density reaches infinity.

  • Not to forget Black Holes for Dummies, to add to the ever populair for-Dummies series. Avable at your local bookseller.
  • Yeh, probably. Maybe it was named after Wilhelm Conrad Röntgen, the guy who discovered X rays.
  • but neutron stars would emit light, which said black holes do not.
  • Okay, if black holes don't exist, then explain accretion discs and the huge jets coming out of them, along with the massive amount of x-rays. Quantum singularities exist, and we have a good amount of corroborating evidence to that fact.
  • When are we going to get to the stage when we can actually launch human-piloted (or not) craft and physically go out and explore these things and prove them right or wrong?

    When we have volunteers that are nuts enough to take a ship close enough to something that is "mostly harmless" and sane enough to actually tell something about useful about, should the somehow survive.

    Black Hole(tm), safe when used as directed.
  • Seyfert galaxies house active supermassive black holes in a central region no larger than Earth's solar system. As the black hole consumes nearby stars and gas, it unleashes tremendous amounts of energy...

    Doesn't this undermine some parts of the 'big bang' theory? According to this theory the universe started in one central area and exploded. There was no material to consume.

    Mark [zwienenberg.com]
    "Only two things are infinite, the universe and human stupidity, and I'm not sure about the former."
  • um... why do death and birth have to be associated with evil and good? they are part of nature... shiva is not evil just because he/she/it destroys
  • to put in in terms that a dummy like me can understand you are trying to say black holes exist because they have been spotted, but that what they are is just mathmatical theory?
  • this is probably far beyond our lifetime... but theories exist on "hyperspace" travel... mostly in the realm of sci-fi... but then again lots of stuff that exist now used to be sci-fi... i wouldn;t put much past the ability of human ingenuity...( 'cept maybe not killing ourselves off in the next melenium)
  • i can't remember exactly when but several years ago after some of the hubble data was processed, they discovered that the calculations for the age of the universe based upon the distance and velocity of the farthest objects they could measure would place it at only 12-14 billion years old... but we have stars that are supposed to be older than that.
    time magazine did an intresting article on "dark matter" because acroding to the article the only way that the universe could be older, if we subscribe to the big bang, is that we must have calculated the mass of the universe wrong... hence there was alot of matter out there that we didn't see before... one of the theories is that there are alot more black holes than we originally thought...
    maybe the existence of super-large black holes in the center of galaxies could account for that?
    any thoughts from people?
  • Black holes are the result of a physical theory. Stars maintain their size and shape because the release of energy (mainly through fusion) is in the form of light that exerts a pressure outwards as it escapes. This balances the pressure of gravitation inwards. When the star can no longer produce enough energy to maintain this balance, the star collapses because the gravitational pressure is still there. Eventually, the surface gravity is so great that not even light can escape. This is what makes thes objects both "black" and a "hole".
  • Dark matter is more relevant to the evolution of the universe than to its age. The estimates of the age on the universe are based on what is loosely called the cosmic distance ladder. This is a chain of related observational data that eventually let us calibrate the value of the Hubble parameter (a.k.a. the Hubble constant, even though we're not sure that it *is* constant). If the universe were dense enough that its expansion since the Big Bang is slowing down, then dark matter would have a role in things. However, there are other observed phenomena, such as the relative lack of observed structure in the cosmic microwave background, that support quite the opposite conclusion. Overall, the question is still an open one, but the opinion of the astronomical herd seems to be that the universe is open (i.e., there isn't enough dark matter to slow down the expansion that started with the Big Bang).
  • Before we even think approaching a Black Hole, we should first find cheap way getting of earth (can anyone say Space elevator?).

    After we get out, we must colonize the rest of the planets in our solar system, preparing ourselves to go to our closest friend, Proxima Centauri.

    If I lived enough to see that I would be very happy, and probably very very very old.
  • Funny, I always viewed the Black Holes as the ultimate destroyers of the universe, now they seem to encourage the birth of stars!

    Amazing, it's like Shiva being the destroyer and Brahma de creator, all the while they are the same being.

    I guess that balances the evil with good, so their Karma is also kept balanced, who would guess that even Black Holes, and Gods would worry them self's with such a thing ;)
  • Doesn't this undermine some parts of the 'big bang' theory? According to this theory the universe started in one central area and exploded. There was no material to consume.

    To keep it short and simple: no. Big Bang theory is actually some kind of misnomer because it appeals to the idea of a 3d explosion which is not the correct metaphore to describe the evolution of a Friedman-Lemaitre universe, let alone inflation theory. Also, the existence if black holes in this (galaxy-evolution) context isnt even remotely connected to subject.


  • there is no proof that black holes exist! They are still entirely theoretical constructs,

    All ideas are theoretical constructs. Numbers are theoretical constructs, Quantum Theory is a beautiful theoretical construct. However i do not see you getting skeptical of the number on your bankaccount, nor violently disagreeing with QT (oh wait my processor is operating according to an entirely theoretical construct). Now i now that space-time singularities freak ppl out and that the observational evidence is necessarely indirect, but you completely misjudge physicists and astronomers (who actually understand the theoretical framework), if you assume that this is an issue painfully overlooked.

    and whilst standard general relativity seems to demand their existance other formulations of general relativity don't

    G.R. does not demand, but rather allows their existence. Other formulations either are abstractions of GR (and therefor embed it) or have a different behaviour and are disqualified time and again by observations (for example the gravitational lensing effects).

    and we can't even say what a unified theory will predict once they finally get from being airy speculation to a solid theory.

    *sigh* To get the record straight: it is general relativity that has an excellent record and firm and elegant theoretical basis (and it is a bitch to disprove). Are you suggesting throwing it away for a unfinished unified theory that is speculative, in flux and extremely hard tot test?. If the US doesnt wanna build Large Hadron Colliders you might never find out the connection between metrics and the other interactions.

    It is still a very real possibility that astronomers and astrophysics alike have simply seized on a theoretical result without any thought of whether it is valid and used it to justify all kinds of celestial phenomena which have nothing to do with black holes at all. There's no excuse for such slipshod science, and it's all too likely that future scientists will look back and laugh.

    The only person flirting with slipshod science is you my friend. And you're general argument that astronomers are just plain wrong might be true, but they are certainly a heck of lot more informed than you. And history learns that the future scientist will most likely look back in wonder and respect. The development of human knowledge and understanding is a cumulative affair. Research done by one is used as a basis for those who follow, one generation gives knowledge and a treatise from which to live to the next.

    Bernard de Chartres (12th century) said: "In comparison with the ancients we stand like dwarves on the shoulders of giants". This might well be said of scientists in this age.

    Wheeler has a lot to answer for with his glib coining of the phrase "black hole". Do you think people would be so ready to assume their existance if they had been called "dark stars" as they once were? This smacks more of faith than reason.

    Black hole is a term that stuck because the general public (ie you) thought that it was more catchy (people also like and misunderstand 'Big Bang'). Before this they were referred to by the community as "frozen stars" (or "dark stars", thought up by Laplace), but scientists who are working with it in da math, couldnt care less whatchacall it.

    Maybe it's time to catch up on the literature before posting. It is not hard: try "black" "hole" "faq" keywords.

  • My guess would be that '^^' is a 'translation error.' In the German language, there is extensive use of umlouts (sp? I only know how to pronounce it) -- that is, letters with two dots over them. That '^^' could have been a ë, ä, ö or ü.

    --
  • there is no proof that black holes exist

    So what? You know, sometimes you make certain model assumptions, and you start out by assuming certain things, and see where you end up.

    I agree that it is hard to prove the existance of black holes, and the only evidence I will accept as firm, is that you can resolve a structure where you have a bright accretion disk with matter falling into the black hole, and then it suddenly goes black in the center. It's be a while before something like that can be done. Yet, I'm going to write in my master's thesis that "I assume that the standard black hole model for quasar energy production is essentially correct".

    You see, Black Holes are really quite simple. It's just that gravity collapses an object beyond any other known force. So, you've got something really simple that explains an awful lot of things. So, you'll going to have an awful lot of explaining to do if you reject black holes. Of course, you have the full right to reject black holes, but I am pretty sure you'll have serious trouble coming up with anything that isn't effectively cut down by Occam's Razor, i.e. you can't find anything simpler that explains all the facts. I think.

    The advantage of theorizing based on such assumptions, is further that you can come up with many more empirical consequences, which means that you get the chance of actually putting the entire model to test. In other words, that people come up with things like this, is necessary to test the model and may lead to the model being abandoned.

    So, the Black Hole model is a great model, at least compared to many other models people have faith in.

  • There is an alternative theory of gravitation formulated by Yilmaz. He theorised that the source of the curvature of space-time is the gravitation field itself. Thus Eisteins equation (1/2.G,mu^v = Tau,mu^v) need modification and becomes: 1/2.G,mu^v = Tau,mu^v + t,mu^v

    Using this there are no space-time singularities or event horizons - so no black holes then.

    It is sadening that so many people base new theories around the existance of black holes that ultimately could prove to be a waste of time and good minds.
  • The article is rather confusingly written, because taken at face value, it is not clear at all what has been shown by this study.
    It says that the investigated galaxies were Seyfert galaxies, i.e. galaxies that presumably harbour a massive black hole. Furthermore, it says:
    (a) "Previous research had identified the galaxies they studied as having some characteristics of starburst galaxies.", and
    (b) "Starburst galaxies in the new study also were near to or interacting with other galaxies"

    This would imply that the investigated galaxies were not a random sample of Seyfert galaxies, but selected on the fact that they also show star formation.
    Obviously the theory that both are related could only be proven with a random sample (i.e. take N Seyfert galaxies and prove that most/all of them show violent star formation, or vice versa).

  • by Anonymous Coward on Wednesday November 08, 2000 @01:52AM (#639621)

    As interesting as all of this speculation is, there still remains one unfortunate fact which people here seem to have missed - there is no proof that black holes exist! They are still entirely theoretical constructs, and whilst standard general relativity seems to demand their existance, other formulations of general relativity don't, and we can't even say what a unified theory will predict once they finally get from being airy speculation to a solid theory.

    It is still a very real possibility that astronomers and astrophysics alike have simply seized on a theoretical result without any thought of whether it is valid and used it to justify all kinds of celestial phenomena which have nothing to do with black holes at all. There's no excuse for such slipshod science, and it's all too likely that future scientists will look back and laugh.

    Wheeler has a lot to answer for with his glib coining of the phrase "black hole". Do you think people would be so ready to assume their existance if they had been called "dark stars" as they once were? This smacks more of faith than reason.

  • There has been a plethora of research into massive black holes and their relationships to their respective galaxies. Of course most of the work is theoretical, but it is incredibly interesting!

    The work is lead by a group of physicists who call themselves "nukers" [noao.edu], and a lot of information can be found here [utexas.edu].

    The main questions that they have been struggling to answer are:
    1) What factors about a galaxy do the size and mass of the blackhole at its center dictate?
    and 2) Is it neccessary for a galaxy to have a blackhole at its center?

    It is this first question which ties directly in with the rate of star formation and such material. If you're interested at all in the subject, I highly suggest checking out the links I provided above. (Yes, I'm too lazy to cut and paste the links again...)

    --- I've been up for way too long, so I apologize if at times I made no sense. Just follow the links.
  • by foul (89373) on Wednesday November 08, 2000 @01:17AM (#639623) Homepage
    Saying that black hole jets help trigger star formation is very different from suggesting that these two phenomena are linked in a single set of evolutionary processes.

    For example; it is widely believed that most stars in galaxies are being formed in relatively short powerful bursts. These bursts are triggered by the hierarchical clustering of subgalactic components. In many of these 'merging' galaxies spectral analysis does not show the black hole fingerprint (strong forbidden lines). These lines are hardly attenuated by dust, so if you dont see them it is unlike that the galaxy hosts an active BH.

    Actually, in the merging scenario, which is favoured by theoreticians and observers (as opposed to the unlikely single monolithical collapse), the hardest part is to cool down star formation! Read: we have a hard time understanding what processes actually inhibit SF, let alone promote it.

    Altho this research sheds new light on how complex the live and birth of galaxies is and how we lack in detailed understanding of the physical processes and interactions, to claim on the basis of a study of 14 Seyfert galaxies that this amounts to a breakthrough in this field is tentative.

    If you read these type of articles precisely, you must be sensitive to the words ['may', 'might','help','possibly','suggest'] and give credit to the researchers effort to be cautious.

    It must be pointed out that that if you really want to find out what the relation between BH and SF is you need to go to the high redshift universe. The problem is that hi-z sources are just to damned faint to study spectroscopically (no... hubble is useless here).

  • by vapour (102049) on Wednesday November 08, 2000 @12:52AM (#639624)
    It'd serve many people well to have a little understanding of the physics of a black hole.
    Here are a three of my favourites:

    Virtual Trips to Black Holes and Neutron Stars Page [nasa.gov]

    Jillian's Guide to Black holes [syr.edu]

  • by DeadVulcan (182139) <dead...vulcan@@@pobox...com> on Wednesday November 08, 2000 @04:36AM (#639625)

    As interesting as all of this speculation is, there still remains one unfortunate fact which people here seem to have missed - there is no proof that black holes exist! They are still entirely theoretical constructs...

    The history of science is one of constant theorizing. Usually, a theory falls out of favour when we try to extrapolate it too far, and we realize that it doesn't fit any more. This is exactly the status of black holes, and this kind of speculation is exactly the kind of extrapolation that can disprove the theory.

    However, I feel that unless you have a better theory, or unless you can decisively show how our current theory is sorely lacking, you don't have much grounds to lambaste our current scientific understanding. If you do have such a contribution to make to this discussion, I'd welcome it (it would be much better than my own comment).

    There's no excuse for such slipshod science, and it's all too likely that future scientists will look back and laugh.

    The history of science is filled with all kinds of foolishness, and no doubt our age will be included in that fine tradition. However, it's completely unfair to "laugh" at our ancestors' understanding of the universe without taking into account the historical, social, religious, and technological context.

  • by pcwhalen (230935) <pcwhalen.gmail@com> on Wednesday November 08, 2000 @05:23AM (#639626) Journal
    Washington, D.C. = Senator Strom Thurmon denounced the reckless attitude of various stellar objects, including what he termed "voracious black holes" for unusually high rates of star births seen in some galaxies.

    "Clearly, the family values I so highly espouse are sadly lacking with these voracious black holes, and this is the reason these holes see such unusually high rates of star births.".

    The prune-like Senator went on to extoll abstinence for the Black Holes and other stellar objects. He then left for a prolonged nap.
  • by potcrackpot (245556) on Wednesday November 08, 2000 @02:11PM (#639627) Homepage
    I will say this: Black holes are not a theoretical phenomenon. They are an OBSERVED phenomenon. You can SEE them.

    They are called black holes because light cannot escape once it has fallen in (in lay terms. Light takes forever to fall in. Matter doesn't). Whatever the technicalities, once it has fallen past the horizon, nothing, not even light, is going to escape. Hence the blackness. Hence black hole.

    We can observe them (i.e. SEE) them by (a) their actions on other massive objects, e.g. in binary star systems etc. where the other member appears to orbit nothing, and (b) by the radiation the matter in orbit AROUND (not WITHIN the horizon, i.e. the black bit, but orbiting outside it), because as matter falls in, it emits radiation - in the most efficient process known. Makes fusion look like a candle to the sun in comparison. This radiation is redshifted by the mass of the black hole. So it has a kind of halo (in X-ray frequencies, not visible light).

    Also, the maths works, i.e. you can work out it's mass from it's effect on everything else e.g. gravitational lensing, then work out it's radius by looking at the radius of the 'halo', and these figures agree with those predicted by the Schwarzschild (non spinning) and Kerr (spinning) metrics of general relativity.

    You people saying they don't exist, crikey, you'd think the earth was round or something! Read things, take it in, and don't act like Prince Charles (non UK residents - acted like a fool ranting about man/science recently, without knowing what he was talking about).

    Any physicists reading this please bear in mind that I am trying to explain something complicated to people with no background in this subject...

"Now this is a totally brain damaged algorithm. Gag me with a smurfette." -- P. Buhr, Computer Science 354

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