It is widely accepted that supermassive black holes (SMBHs) sit in the centre of elliptical galaxies or bulges of spiral galaxies. They suck in as much matter as possible, generating blasts of radiation. Stars, gas and everything else nearby forms a compact “halo” and then falls to a gravitationally enforced death spiral. The greedy nature and the sheer size of these black holes have led to the idea that dark matter may supply (or may have supplied) the SMBH with some mass during its evolution. But could it be that dark matter may not be significantly involved after all? This might be one cosmic phenomenon dark matter can’t be blamed for…
Black hole accretion disks are compact halos created as dust, gas and other debris are pulled toward a black hole event horizon. Accretion disks radiate electromagnetic radiation, and the frequency of which depends on the mass of the black hole. The more massive it is, the higher the energy of radiation emitted into space. In the case of a SMBH, the huge mass causes very bright emission as the matter from the accretion disk falls into the event horizon (the point at which gravity becomes so strong that even light cannot escape). As accretion disk matter falls toward the event horizon, approximately 10% of the mass is converted into energy and ejected as X-rays. This is a far more efficient energy conversion rate than the most efficient nuclear fusion reaction (approximately 0.5%). This X-ray emission can then be observed, creating a quasar, signifying a SMBH is driving the active galaxy.
Interestingly, an SMBH is not thought to be formed from single dead massive star. They are thought to have been created from a “seed” and then grown over billions of years. The source of the mass feeding the growing SMBH comes from its accretion disk, but it is uncertain what form the matter comes in and at what rate it “feeds” the black hole. There are several possibilities as to how the largest black holes were seeded, but two are the most widely accepted:
- Intermediate black holes (with masses of several thousand Suns) are created by vast clouds which collapse to a single point. Black holes form and accretion disks grow.
- Massive primordial stars (the first stars, formed only 200 million years after the Big Bang) of a few hundred Sun masses may have collapsed to create smaller black holes, again forming accretion disks and growing over billions of years.
The mechanisms affecting the rate of accretion disk growth are not so clear-cut. Some theories suggest that huge quantities (most of the black hole mass) comes from dark matter. However, as dark matter is “non-baryonic” (i.e. the opposite to baryonic matter – the matter we know, love and observe in our universe) it will emit very little radiation as it falls into the black hole event horizon. If this is the case, SMBHs would grow disproportionately when compared with radiation emitted from galactic centres (only baryonic particles will emit X-rays).
New research headed by Sebastien Peirani (at the Institut d’Astrophysique de Paris, France) suggests only a very small fraction of a SMBH is composed from dark matter as it evolved. Dark matter is predicted to be collisionless and will be scattered very easily by baryonic gas clouds and stars. It seems unlikely that dark matter will be able to stay inside the black hole’s accretion disk for very long before it is repelled by all the “normal” matter being pulled toward the event horizon.
By modelling a “typical” accretion disk and comparing the results with observations of quasar luminosity, the French group found that most of the matter fuelling the SMBHs is relativistic baryonic matter. At a critical distance, outside the black hole, baryonic matter from the accretion disk is accelerated to a significant fraction of the speed of light, emitting radiation. Comparing this with simulations of a collisionless disk (i.e. the characteristics of dark matter), the baryonic model fits observations the best.
“Application of our results to black hole seeds hosted by halos issued from cosmological simulations indicate that dark matter contributes to no more than [approx.] 10% of the total accreted mass, confirming that the bolometric quasar luminosity is related to the baryonic accretion history of the black hole.” – Abstract from “Dark Matter Accretion into Supermassive Black Holes“
Source: arXiv
To Cathbad:
I’m not really interested in your opinions about the way I write my articles, and I’m sure nobody else is – I’m reporting on actual published papers, I don’t make this stuff up.
If you really want to argue the toss, argue the science, give us some compelling arguments so we can improve our understanding of dark matter theory. I am no expert, you obviously are, so please put together a coherent paragraph or two without hiding behind your username and tiresome outbursts.
And the name is Ian, or O’Neill, not “Neill”.
Thanks, Ian
I thought dark matter didn’t interact with regular matter.
I can take critique, but saying an article is “BS” or “lurid botch” is *not* constructive criticism, it is brainless commenting. If you want me to improve, challenge me and the science, don’t insult the article.
Feel free to email me at the address at the top of the page and I will be more than happy to answer your concerns with my writing ability. If this makes me a coward, then there is no hope for me.
Otherwise, I’ll look forward to your next round of intellectual comments on my future “pseudo scientific” articles.
Thanks, Ian
Dark matter does interact with regular matter, but only through gravity and the weak nuclear force. Dark matter just doesn’t “feel” the electromagnetic and strong nuclear forces.
Theoretical physics is just that, theoretical. Physicists set out with an idea and the idea is either proven or disproven. In the article above, the investigators take a dark matter *theory* (call it speculation if you like) and try to understand it better and compare their results with observation. Their conclusions will be used by scientists in the future to understand the nature of our universe. In this case, as nothing has been proven there will be a lot of “mights”, “ifs” and “buts”. If you don’t like this, and feel I should avoid such topics and concentrate on science facts, don’t read these theoretical articles. Simple.
And so far, I’ve had no constructive criticism and I have no email from you, so I can only assume you are intent on arguing for the sake of arguing.
I’ll leave it there to shout whatever comes to your mind, enjoy yourself.
Many thanks for enlightening me, Ian
I’m still highly dubious about the whole “dark matter” thing. It sounds to me (as an interested layman, rather than a professional physicist) like exactly the kind of thing you’d expect to have to add if the fundamental equations are wrong somehow.
Time will tell, obviously.
“Dark matter is predicted to be collisionless and will be scattered very easily by baryonic gas clouds and stars. It seems unlikely that dark matter will be able to stay inside the black hole’s accretion disk for very long before it is repelled by all the “normal” matter being pulled toward the event horizon”
This statement makes no sense. If DM is collisionless both with itself and with baryonic matter, then no scattering/repulsion can occur. If only gravity is at work, then the opposite should happen.
Neill at his best.
Congrats.
Again only some loosely coupled astrophysics buzz words and a dash of might and woulds and voila….a pseudo scientific article for the jerks.
The key to an even more compelling BS composition is now the influence of dark energy through time.
So it will become obvious that 100 million years after the inflation period dark matter really interacted with not yet exsting elliptic galaxies and implanted the huge stars that later formed the black holes acquiring the primordial black holes. But only the dark energy could explain the would of the might be in the negative curvature of the black holes event horizon that exchanged brownies as force carriers with dark matter. Think about that Neilly.
I a n
you write, you have to stand critics.
Dont be such a coward and hide behind ‘reporting on articles’.
You write this lurid botch or at least you repost it for a certain reason……
Write or edit a better one and you will get famous.
My main beef with dark matter is this, there is no evidence what-so-ever to support that it exists in whatever quanity anywheresave for that it helped explain what other-wise could not be explained in some astrophysics calculation.
I keep seeing people talking about
” gravitational lensing ” as evidence that dark matter exists, but gravitational lensing only means something is warping the view of a particular area of object and does not automatically mean the cause is DM, and to state that it is without evidence is clearly biased in favor of a particular speculative unproven belief.
DM is treated as fact from what I have read & heard so far, and nevermind that it has not been proven to exist, as all these people just jump onto the band wagon of unquestioning belief because it is the latest popular buzz word, and while it may help them explain things that would other-wise remain unexplained, that does not automaticaly mean it is correct by any streatch of the imagination.
People who invistigate science should remain objective & shy away fom popular beliefs ( which is little more than Group Think ) & instead concentrate on facts, and the fact is that DM is just a unproven theory, not scientific fact.
Cathbad, criticism is fine so long as it is constructive.
Hey all,
I’ve been reading these theoretical physics stories for a long time and would feel better if some of them actually turned out by observation to be true. So, let’s count how many that is in the past 5 years or so: Oh yeah, now I remember, ZERO!!!
It is constructive, but you dont want to hear it.
Learn to rely on facts and not mights and woulds.
Seperate clearly between solid phyics and accepted scientific work and pure speculation.
Leave the ground of giving feelings and anthropmorphic motives to things like black holes and dark matter and just by that avoid lurid BS and botch.
but since you are so experienced writer you know all that already.
Cathbad,
Since all of this dark matter and inflation theory have become so popular lately, I have read at least 20 articles in the last month regarding Strings, Branes, tachyons and extra dimensions of space, dark matter, dark energy, Black holes, Calabi-Yau manafolds, and other new concepts. The fact of the matter is, at this point, we don’t have a freakin clue about any of this stuff. It is 100% Theory with no current way of observing. People put forth their best ideas and some stick… others do not. world is not flat, not the center of the universe etc… Even E=MC2 does not look like it is the magic formula anymore.
Since you felt that IAN’s article is so far off the mark, please enlighten us with your understanding of this topic, in fact, since you feel so strongly about it, why don’t you write a short article about it. Write it in the way only you feel you can do and lets discuss.
Trashing someones work, with out being able to offer an alternative viable viewpoint, is like being a bully on the playground. Since you have no clue, you try to make yourself look good by putting down others. Pathetic.
Lets see how big your stones are… Why don’t you write a short article on this blog for us all to review and remember to put your real name and email on it.
what?? is that crickets I hear??
Following along an tremendously more sober vein of thought, I am reminded of the dark matter = carbon whiskers theory. Could matter be so doggedly massive using atomic structure, that dark matter/carbon whiskers interact only so much as to get out of the way of whatever matter oriented event is transpiring, and once the event is complete the dark matter simply returns to its approximate position prior to the event?
To put a finer hair on it (ah hem) You trim your beard in the sink. You run a little water in it. The hair will just float a while, or shift positions, even ride along with the water (baryonic matter), but unless other forces are brought into play, the water/event will subside, leaving the whiskers (dark matter) relatively unscathed. And it would not be hard to imagine a force equal to surface tension between baryonic and non-baryonic entities.
I think Ian’s write up was slightly misleading in the way it described the process by which dark matter is predicted to be excluded from black holes. Dark matter is assumed to only interact by gravitational forces, not electromagnetic, and likely not weak or strong nuclear, although that is even less certain. I believe the key finding in this study is that what causes normal matter to spiral into a black hole is in large part the electromagnetic radiation given off when charged particles are accelerated in these very fast tight orbits.
Since the dark matter does not radiate by this mechanism, it does not spiral in as rapidly and thus hangs back while the baryonic matter radiates it’s energy and spirals down into the hole. It is not that dark matter is repelled by normal matter, it is only that dark matter does not experience this dissipative effect since it does not interact electromagnetically.
Rich L.
damien_58,
to the best of human knowledge, dark matter is at 23% now v. 63% 13.7 GY back, http://map.gsfc.nasa.gov/news/index.html. WMAP measures the density of baryonic and non-baryonic matter to an accuracy of better than 5%, http://map.gsfc.nasa.gov/universe/uni_matter.html
Ian,
Some people just do not get the depressing odds of ironing out the knowledge and role that scientific ideas play in supply chain to keep the process going. Thanks for the reporting on what is going on today, so some of us can balance it with the established facts that belong to the history of science.
Gentlemen, a little decorum, please.
First, some positioning. I don’t like dark matter. I wish there were observations to support dismissing it. There aren’t. After reading everything I could find about DM for the last couple of years, and extensive forum discussions, there isn’t any better explanation at this point. Try thinking of dark matter as some sort of non-interacting distributed mass, composed of who knows whats that are really difficult to detect.
Secondly, if you don’t like the idea, offer some constructive and testable alternative that doesn’t explain dark matter at the cost of all the rest of well tested and confirmed physics, from quarks to the largest structures in the universe. I think you’ll find yourself proposing some version of – guess what – DM.
That’s right John,
Dark Matter is, in my books, simply a digestible concept for a solution to a difficult set of questions. The idea of dark matter is of non-interacting weirdo stuff. We can all wrap our brains around that. That doesn’t mean that the solution will be the same in ten years. But why call it the “Missing Matter Solution” when Dark Matter is such an attractive name? Science tries to solve problems with the simplest solution and if we could just detect/hold/”see” this stuff, then that would solve this dilemma most satisfyingly. Rewriting years of physics doesn’t seem quite as eloquent.
Ian,
Good for you for reading the comments sections. I’m sure you have other things to do. I come to Universe Today religiously and really enjoy it. My favourite (sorry, Canadian) articles are the theoretical ones about Dark Matter and fundamental forces. I’m not a physicist but I know what sounds like good science and what sounds “out there”. Theories are just as interesting as discoveries and make the universe a fascinating place. I like to think my simple thoughts might be as close to the mark as the real brains in the field.
Keep it up!
Your fan,
Pete
I’m a physics student. I am currently in the middle of astrophysics. I have been reading UT for about two years now maybe. I love how the trolls come out in full force in the comments section. Although it is unusual to see an author defending his work on the comments, its not unwelcome.
The Dark Matter debate is killing me.
You all do know what dark matter is, right?
Dark matter is the answer to the question “why is the milky way a spiral when the visible mass is not enough to maintain this interesting shape?”
There’s nothing about interacting with particles, whether they annihilate themselves, etc. Thats the best part. How is anyone able to describe the behaviour of a bunch of particles that only exist on paper? ITS Not Real.
Why dark matter? Simple. Because no one has the stones to tell Isaac Newton that his calculations were off.
Thats it yall. Thats the whole argument. We can all go back to pretending we’re experts about things that we don’t know anything about and know that no one else does either.
These articles are great, but come on. Hundreds of pages of writing about particles that just don’t exist, applying properties to some invisible matter that only interacts with gravity? What’s more likely? 80% of the universe is invisible and intangible and only interacts with the rest of the universe just so we can fit it all within our presumptuous crosshairs, or perhaps a human that lived 400 years ago might not have carried a one?
Lets all just get over ourselves just a little bit.
I a n,
feel confirmed and criticised. Your fame is to play the sacrificial lamb.
Your fans like the lurid botch.
Now be a man and stand the fact that there are some people out that see and name the disease. No not me. read the comments.
You do ignore what you dont want to hear. Your choice. The things are still visible.
I can confirm you are an eloquent and serious writer for your fandom, but neither your lurid style (GREEDY holes and DISLIKE of DM,…..) nor this infusion about a computer simulation (yes a simulation) qualifies you as a scientific jounalist….and you know it.
Hide in whatever excuse you prefer.
Rather patronizing nor ignorance will save you from being charged a yellow press copycat.
About the article. It says no more and no less that a computer simulation delivered an upper bound of 10% (could be far less) for a DM contribution to the luminosity of relativistic matter falling into a massive black hole. I am here not refering now to the fact that DM is a picture, a model not a empiric result,. This is just the thin ice your stories stand on.
What you make out of the simple computer simulation paper ? A lurid story about greedy holes that dont like DM.
Is that science, science exegesis, simple rephrasing in fandom scene language ?
Be a man and stand the critics that tell you that this is not really a quantum leap, neither in your kind of ‘theorethical physics’ nor in scientific journalism.
Go ahead and rejoice in your fans and accept that some dont fall from your intellectual bremsstrahlung.
Finally Bob, great idea to ask me for an article.
What do you expect ? the same kind of knock off like Ian likes to spread for some bucks of fee ?
There is not much more to say about this analysis paper than what is already said before.
Do you expect me to bloviate in anthropomorphisms and some free association on unsave ground ?
Make Ian your jester and let him waffle on speculative parts of theories, since it enriches your creative process of generating new theories the scientific world has waited for.
This is like pinpointing the physical meaning of the negative solution of a squareroot.
You can do it if you like, but dont expect standing ovations for it.
As a trailer I admit that Ian is good in inflating an ant to the size of an elephant and impressing the woodlouses with it. Thats a talent indeed.
To Ian vs cathbad:
Later this year CERN will be launching the Large Hadron Collider, whose energy capabilities are robust enough to probe for the Higgs boson, and perhaps reveal unseen properties of dark matter and dark energy. THERE WILL BE SURPRISES GALORE.
Cathbad, keep your eyes and ears open, bu t remember to keep your mouth shut,
Any new revelation on dark matter and dark energy is what we look for.Please dont call my uncle SMB greedy.Gravity pushes food to it.Uncle does not hanker for it.
Fred I can wait for the dark energy and the non-primordial black holes from LHC.
You escapists and dreamers just have no respect to real world scienctific work.
I am sure that your kind is waiting for lurid botch freely associated from upcoming LHC results.
Ian can feed your monkeys.
PCY : You respond to
“Dark matter is predicted to be collisionless and will be scattered very easily by baryonic gas clouds and stars. It seems unlikely that dark matter will be able to stay inside the black hole’s accretion disk for very long before it is repelled by all the “normal” matter being pulled toward the event horizon”
With:
“This statement makes no sense. If DM is collisionless both with itself and with baryonic matter, then no scattering/repulsion can occur. If only gravity is at work, then the opposite should happen.”
First, the collisionless plasma model is, in essence: A model of a plasma in which the density is so low, or the temperature so high, that close binary (two-body) collisions have practically no significance (on certain timescales) because the time scales of interest are shorter than the collision time. Yields valid physical results for timescales much shorter than the average collision time in a real plasma.
Collisionless dark matter ‘clouds’ can interact gravitationally with baryonic gas (largely plasma), or with itself. Collisionless simply implies that there are no, or very few, direct two body collisions. (Consider the effect of an asteroid that passes very close to the earth but does not collide. It interacts gravitationally and may be ‘scattered’ into a new orbit without a two-body collision.
Wow, a scientific web page bitch fight.
Never seen one of these before [save into Bookmarks]
This should be, and already is, a lot of fun… 🙂
Fascinating topic and discussion. Ian, my wife teaches writing as her profession. In her educated and trained opinion, your writing is fine. Cathbad will go away faster if no one responds to him. When deciding about critcism, consider the source. The writing style of his comments effectively remove him from the realm of serious critique. The best way to deal with the peanut gallery is to ignore them.
But to the real discussion… My only credential is a bachelors in physics. I have problems with the concept of dark matter and dark energy myself. I suspect that although the math describing gravity in the local frame of reference works quite well, there are areas where they aren’t as effective. There are many issues at the quantum scale, obviously, and possibly we should consider that we need to define a new scale, that of extreme distance.
Another idea of interest would be the concept that areas of space/time could have higher energy densities embedded in the fabric of space/time itself. These would not be immediately apparent, because at any point in seemingly “empty” space/time the energy (expressed as vectors) sum to zero. But they could conceivably create “heavy spots” in space/time, a local curvature that isn’t created by any visible mass or energy. Alternatively, areas with unusually low embedded energy would create “light spots”.
How this concept would interact with the data from the anisotropy map of background IR, which I understand to be the basis for the conclusion that space is “flat” in our visible universe, I don’t really know. But its an interesting area to explore.
lol
Dear david why should your educated trained and commercial wife peck an eye out of Ian.
they are the same kind.
They make their money with the ant to elephant size inflating.
And why do you think your patronizing would impress me and the other sceptics when it comes to questioning the scientific and journalistic value of the botch.
It is not important if it is written correctly from a craftsmanship point of view.
Even a perfectly mastered DVD in a platinum box can contain crappy story and actors.
Your bachelor seems not enough to see the epistemologic limits and the difference between science and speculation.
Let us wait for the next ant inflation.
In extreme distance would not the expansion/inflation that creates new space contain gravitational eddy currents that would propergate the real God particle- time-to affect this lack of matter?
Mark I 100% agree.
This looks much more credible than the negative squarerootsolutions I read before.
The beauty is in the precision when you formulate the ultimate theory.
Since Ockham’s razor this has been always a good rule.
I might add that the dualism of particle and waves also allows a God wave function and only some expectation values have a sufficient probability to burn ideas of energy vectors into bachelors brains.
Cathbad’s broken. Obviously intelligent but obsessively and compulsively argumentative. She seems unable, unwilling, or afraid to provide an objective and rational posting. The unrelenting hostility suggests fear. The way Cathbad’s sentences chain disconnected concepts unerringly toward a hostile conclusion suggests schizophrenia.
Consider the sentence, “I might add that the dualism of particle and waves also allows a God wave function and only some expectation values have a sufficient probability to burn ideas of energy vectors into bachelors brains.”
what is the current speculation of the effects of graphite wiskers on the current theoretic amount dark energy? (and is there any effect dark matter?) what does this translate into for the future state of the universe, if graphite wiskers really are offsetting the brightness of our “standard candles”. Is M~still making much progress or receiving more recognition? *as I hope it does
i was thinking of my own self-conjectures…. is it possible that the other nearby universe we derive gravity from (and ?? the weak nuclear force, as well as the even weaker interactions which seem to cause the quantum movements of sub atomic particles) simply share and help to attract, and build upon certain aspects each other even during the early times of inflation right after the big bang to the times of our galaxy formation? let me get this straight: are matter and dark matter (whatever it is, perhaps if M~theory/ String(s) theory is correct that it really is the matter or effects of it in the nearby universe(s)) weakly interact but only via the warping of gravity and pehaps only on a minute scale even on the subatomic level or perhaps a mysterious type of neutrino (*I believe its the relic neutrino) is the culprit, however this is *unlikely due to the fact that not one has been seen (yet?).
~ i mean even this is easier to swallow than particle that just do not seem to exist or at least be detectable… <- fair criticisms,
…and if graphite wiskers does kill Dark Energy, the fact of the matter is: even if graphite wiskers are obscuring our type 1A Super Novas, {and not to mention not one WIMP has been found in the lab}; this doesn’t actually “disprove” dark energy (or dark matter), …but, even you, IAN, i think can agree that this is raising some serious doubts and all Dark issues.
~I wonder what the standard model will look like after the calculation of the effects of the graphite wiskers are taken into account. Anyone know if Dark Energy is still around, or the new estimated amount of stuff? (including Dark matter & *esp* Dark Energy ?)
I can’t wait for the LHC. But it may be dangerous to experience the beginning of the big bang all over. It may launch a black hole, It may blow up the universe. It may lead to something new. But would you risk your life for just more knowledge?
has the theory of propulsion in referance to gravitional properties in a black hole ever been explored or even a small scale attempt to duplicate the properties of a black hole? also if we afilliate gravity w/ magnetics and every planet and moon having some gravitational properties wouldn’t it make sence to build large electromagnetic ships just a little sci-fi and theory
I wonder who cathbad is??? Hmmm.
It is true that Cold Dark Matter is just a theory, and it is not a perfect theory either. It describes the Universe we see pretty well, at least on the largest scales, but on the smallest scales it does not work so well. Nevertheless, this may just mean that Dark Matter is “hotter” than originally thought. Now, maybe the answer is not dark matter, but it is the best theory we have at this moment in time. And remember, just because we haven’t observed the dark matter particle, does not mean that it doesn’t exist. When I was an undergraduate student, we still had not observed the top quark, yet theory suggested that it should exist. And by the time I graduated the top quark had been observed at CERN. I’m sure there were people who didn’t believe in it then, just as there are people who do not believe in dark matter now, and just as there were people in the 19th century, who believed that humans would never be able to fly.
Dark matter is very powerfull it can atract even black holes meteors and more i think that dark matter is the main source of a black hole if dark matter mixes with crystals from the milky way a black hole is formed it is sayd that the more a black hole destroys the powerfull it gets
a black hole started this universe when the big bang if any of you noticed there was a black hole that collapsed destroying itaself but destroying the big bang
the big bang dint just explode it collapsed the big black hole was relly big it spreaded millions of black holes all over the universe no one knows what might be out there but if you ever pass this solar system you will all meet your DOOM
idk man
its true that black holes get stronger as they eat up more and more matter. so then raises the question. what happens when the center of the galaxy eats up all the matter? i mean, in theory, we should have all these supermassive black holes just rolling around in space, because they wouldve eaten everything in the galaxy. and if thats the case then i dont wanna be there when we find one because we’ll all be dead. these black holes are so huge that they just eat up stars like skittles. imagine what it would do to earth? jupiter? our whole solar system? and Roxes kihuata you have no clue in the world do you? when a black hole collapses (if thats even possible for something with unlimited density and mass) it doesnt just break up into little tiny black holes. it would wink out of existance like most everything does when faced with that scenario.