From Daily TechThe Milky Way’s black hole is causing a mess, but isn’t gobbling matter as fast as was thought
One of the most complex and intriguing astrophysical phenomenon is the supermassive black hole. A superdense cluster of mass, the supermassive black hole gobbles up surrounding matter, sucking it into its gravity well. Despite the tremendous importance of these celestial bodies to the structure of our universe, scientists still remain confused about specifics of how they operate.
Supermassive black holes help to shape our universe, but their behavior is still poorly understood
. (Source: PureInsight.org)
It is a well known fact that there is a supermassive black hole at the center of our galaxy, the Milky Way. Dubbed Sagittarius A* (Sgr A*), the black hole is rather weak, due to its inability to successfully capture significant mass. The black hole is bordered by dozens of young stars. It pulls gas off these stars, but is only able to suck in a small percentage of this high velocity stream.
Past estimates put its consumption rate at a mere 1 percent of the gas it pulls away from the stars. Now a new study, using data garnered from the NASA’s Chandra X-ray Observatory, has determined that the black hole is likely eating far less than that figure even — new models indicate it to be consuming a mere 0.01 percent of the gas it sucks off.
Read the rest of the story here.
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Leif Svalgaard (11:19:13) :
Brian (10:31:10) :
One of the best pieces of evidence is the gravitational lensing of quasars by distant galaxies [at cosmological distances] between us and the quasar.
Here you can see how the lensing work:
http://hubblesite.org/newscenter/archive/releases/2006/23/image/c/format/web_print/
pretty neat, don’t you think?
Per PHYSORG.com
Sagittarius A*: Peering Into The Heart of Darkness
January 5, 2010
“These stars are located a relatively large distance away from Sgr A*, where the gravity of the black hole is weak…”
Hmmm?
“The image also contains several mysterious X-ray filaments, some of which may be huge magnetic structures interacting with streams of energetic electrons produced by rapidly spinning neutron stars.”
More questions than answers.
“…lobes of hot gas…”
Might that be plasma, free electrons and ions?
Einstein’s General Relativity predicted “gravitational waves”.
None have been detected even after two generations of detection apparatus.
No “gravitational waves”…well then that calls into question…
James F. Evans (13:22:32) :
“These stars are located a relatively large distance away from Sgr A*, where the gravity of the black hole is weak…”
Hmmm?
As everywhere and always, gravity decreases with the square of the distance.
“The image also contains several mysterious X-ray filaments, some of which may be huge magnetic structures interacting with streams of energetic electrons produced by rapidly spinning neutron stars.”
Electrons are always guided by large magnetic structures
“…lobes of hot gas…”
Might that be plasma, free electrons and ions?
All hot gases are electrically neutral plasmas with equal mixtures of free electrons and free ions.
James F. Evans (13:33:03) :
Einstein’s General Relativity predicted “gravitational waves”.
None have been detected even after two generations of detection apparatus.
No “gravitational waves”…well then that calls into question…
Since gravity is so weak it takes a very large and sensitive apparatus here on Earth to detect them. Several detectors are being build and the experimenters expect positive results. In the meantime Mother Nature’s big laboratory has already given us our first observations of the effect of such waves. All it takes is a close binary of two pulsars, like this pair http://www.astro.cornell.edu/academics/courses/astro201/psr1913.htm
Perhaps knowing a little bit of modern Astronomy might guide your quest. Be assured that you can always come here to seek answers.
Mr. Evans: I read your posts. I look for sense in them. I try to follow your arguments. The facts are unfortunately ambiguous. Any true student of distances to celestial objects will know that there are uncertainties at every step of the argument. I ask you, Mr. Evans, to look to the details. Parallax (even using the data from Hipparchos) does not go out very far. We then must use other means to estimate (estimate) distances to other objects. So we use double and multiple stars. We hope to find among them some Cepheid variables, and use them to estimate distances to globular clusters. Hopefully estimates of the behavior of stars on the H-R diagram are consistent, and so Cepheids can be properly identified by period as to absolute magnitude.
Estimates of distances based on gas clouds are beset with greater uncertainties.
I am old enough to remember when there were first identified differences between Cepheids in Population I and Population II stars, and the distance to M51 had to be revised.
At any rate, one uses a chain of estimation and conjecture to find distances to objects outside the Milky Way Galaxy. There is not absolute agreement even on dimensions within the Milky Way.
When one gets into the redshift/distance relation, one encounters theories of inflation, which make still more assumptions.
On my desktop is a marvelous Hubble photograph: Galaxy Cluster SDSS J1004+4112:Quintuple Quasar. This photograph has it all: Einstein lensing, a marvelous jet, and an object which is arguably much further away then the lensing object. Plus lots of other arcs.
Details. Details. Please consider the details.
I should like very much to see an explanation of the photograph on my desktop which did not rely upon a massive black hole!
mathman (15:00:30) :
I appreciate your concern with the uncertainties beyond our solar system.
It is best to be reasonably sceptical and keep an open-mind.
You are right! Science doesn’t have all the details…
Let me be clear: I’m not original in my thinking, I haven’t invented anything, but I do the best I can to apply logic & reason and to insist on the primacy of observation & measurement — the empirical scientific method.
Man’s ability to observe & measure beyond our solar system is entering a “golden age”, now is not the time to be locked into any one set of ideas.
Follow the evidence to where it leads…and don’t let any pre-existing dogmas prevent you from following the evidence to where it leads.
Since you ask for an explanation that doesn’t rely on “a massive black hole”, consider this:
3 – Dimentional Particle-In-Cell Simulations of Spiral Galaxies
A. L. Peratt, W. Peter, and C. M. Snell
Los Alamos National Laboratory
1990 International Astronomical Union – Provided by the NASA Astrophysical Data System
http://articles.adsabs.harvard.edu/cgi-bin/nph-iarticle_query?1990IAUS..140..143P&data_type=PDF_HIGH&whole_paper=YES&type=PRINTER&filetype=.pdf
“Abstract: …fully relatavistic particle simulations allow a detailed study of a magnetized plasma galaxy model…Simulation derived morphologies, radiation intensities, frequency spectra and isophote patterns are produced by the model which can be directly compared to observational data…of barred spiral galaxies…”
Hold both models (this one and the black hole model) in the back of your mind and as more data is produced from observation & measurement, see which model does a better job of explaining the observations & measurements.
Plasmoid: Plasma-Magnetic-Enity
Maybe there is a reason Dr. Svalgaard was so quick to dismiss observations & measurements that suggest the Galactic Core of the Milky Way has a high value of magnetic energy…
From the ScienceDaily report:
“This research will challenge current thinking among astronomers,” Dr Crocker says. “For the last 30 years there has been considerable uncertainty of the exact value of the magnetic field in the centre of the Milky Way. The strength of this field enters into most calculations in astronomy, since almost all of space is magnetised,” he says.
Dr Jones says the findings will affect diverse fields, from star formation theory to cosmology.
“If our Galactic Centre’s magnetic field is stronger than we thought, this raises additional questions of how it got so strong when fields in the early universe are, in contrast, quite weak. We know now that more than 10% of the Galaxy’s magnetic energy is concentrated in less than 0.1% of its volume, right at its centre,” he says…
“The Milky Way just glows in radio waves and in gamma-rays produced by collisions of energetic particles, and is brightest near its centre. Knowing the magnetic field there helps us understand the source of the radio and gamma-rays better,” says Dr Protheroe.
Now, consider the simulation in the paper by Anthony L. Peratt et al.
Most of all keep an open-mind.
That’s all I can ask.
James F. Evans (16:34:08) :
Since you ask for an explanation that doesn’t rely on “a massive black hole”, consider this:
3 – Dimentional Particle-In-Cell Simulations of Spiral Galaxies
This is a 20+ old simulation of formation of spiral galaxies and has nothing on the extremely spatially small quasars
as more data is produced from observation & measurement, see which model does a better job of explaining the observations & measurements.
that data has been pouring in for twenty years and have already long ago seen the answer.
“knowing the magnetic field there helps us understand the source of the radio and gamma-rays better,” says Dr Protheroe.
which is true but irrelevant for the discussion, and the magnetic energy density in the Galactic core [outside of the black hole] is incredibly small [trillions of times smaller than in a sunspot. Your reply is non-responsive to the topic.
Most of all keep an open-mind.
Not enough. Also know the details, know the recent research, know the theory, know the math, basically: know the subject.
Leif Svalgaard (17:29:15) :
Evans wrote: “Since you ask for an explanation that doesn’t rely on “a massive black hole”, consider this:
3 – Dimentional Particle-In-Cell Simulations of Spiral Galaxies
Dr. Svalgaard responded: “This is a 20+ old simulation of formation of spiral galaxies…” and has nothing on the extremely spatially small quasars.”
Do you have any specific objections to anything stated in the paper?
Dr Svalgaard responded: “…and has nothing on the extremely spatially small quasars.”
The issue of “quasars” goes beyond the subject matter of the paper.
But in a Peratt paper I already provided in this comment thread the issue of “quasars” is covered:
Evolution of the Plasma Universe: I. Double Radio Galaxies, Quasars, and Extragalactic Jets by Anthony L. Peratt, Los Alamos National Laboratory:
http://plasmascience.net/tpu/downloadsCosmo/Peratt86TPS-I.pdf
Review the paper and ask questions, raise objections regarding quasars as presented in the paper.
Evans wrote: “…as more data is produced from observation & measurement, see which model does a better job of explaining the observations & measurements.”
Dr. Svalgaard responded: “that data has been pouring in for twenty years and have already long ago seen the answer.”
I’m not sure what you are suggesting. That Science doesn’t need to consider any more data? That the “Science is settled” move along nothing to see, here?
What?
Seems to me there is plenty of observations & measurements to be made in the future. The cutting edge Science is never “settled”. That’s what makes science fun, interesting, and challenging.
From the ScienceDaily report: “knowing the magnetic field there helps us understand the source of the radio and gamma-rays better,” says Dr Protheroe.
http://www.sciencedaily.com/releases/2010/01/100106193219.htm
Apparently, “Dr Roland Crocker, the lead author, and Dr David Jones both worked on the project while based at Monash University and the University of Adelaide’s School of Chemistry and Physics. The two physicists are now based at the Max-Planck-Institute for Nuclear Physics in Heidelberg, Germany.”, don’t feel they “have already long ago seen the answer.”
Dr. Svalgaard responded: “which is true but irrelevant for the discussion, and the magnetic energy density in the Galactic core [outside of the black hole] is incredibly small [trillions of times smaller than in a sunspot. Your reply is non-responsive to the topic.”
Dr. Svalgaard, do you have a citation or link to support your claim that “the magnetic energy density in the Galactic core is incredibly small.”?
Mr Svalgaard (11:52:06)
Hold on there bucko! Either you’re deaf, dumb or blind I’m not sure which. One thing is for certain you have a serious academic blindspot as you didn’t even
answer my question! Simply amazing, then you go on to push gravitational lensing! You have got to be kidding me. I know for a fact the consensus in cosmology would rather believe NGC7603 never existed. Why, because you and every other cosmologist doesn’t understand it.
So what do you say! Can you answer my question? Got any intellectual balls? Tell you what, if you answer my question I’ll reward you with another example and I’ll even tell you how the consensus made it magically go away. Hey, while I’m at it I’ll even explain why the GPB mission (GPA also) doesn’t confirm Einstein at all. How your answer is supposed to convince me to adopt your paradigm is beyond me.
Again your answer shows that you and most black hole theorists are (can we spell) L-A-M-E. Ignorance is bliss!
James F. Evans (18:52:00) :
Dr. Svalgaard, do you have a citation or link to support your claim that “the magnetic energy density in the Galactic core is incredibly small.”?
According to the article the field is 50 microGauss, that is 0.000,050 Gauss. The field in a sunspot is 2500 Gauss, so the Galactic Core field is 2500/0.000,050 = 50,000,000 times smaller, or 50 million times smaller. With me so far?
The magnetic energy density, MED, is proportional to the square of the field strength, see e.g. http://maxwell.byu.edu/~spencerr/websumm122/node93.html
So the MED in the Galactic Core is 50,000,000×50,000,000 = 2,500 trillion times smaller than the MED of a sunspot. That is incredibly weak.
To take another example: the Earth’s field is 0.5 Gauss, so the MED of the Galactic Core is (0.5/0.000,050)^2 = 1,000,000×1,000,000 = 1 trillion times smaller than the magnetic energy density in your living room. That is mighty small.
Brian (19:29:45) :
How your answer is supposed to convince me to adopt your paradigm is beyond me.
It is not supposed to convince you at all. Some people are beyond reach.
Leif Svalgaard (20:04:34) :
To take another example: the Earth’s field is 0.5 Gauss, so the MED of the Galactic Core is (0.5/0.000,050)^2 = 1,000,000×1,000,000 = 1 trillion times smaller than the magnetic energy density in your living room. That is mighty small.
There are even so many zeroes that I counted them wrong. The correct calculation is (0.5/0.000,050)^2 = 10,000^2 = 100 million times smaller than in your living room. Still incredibly small.
seems like one of the factors of distance indications for quasars is the lyman alpha forest. What is the response for the presence of the lyman alpha forest if a quasar is not at a tremendous distant.
Brian (19:29:45) :
Lets do a thought experiment:
Lets go to the tower of Piza and start measuring the fall of 200.000 solid objects of same size and shape, different materials. We establish that acceleration is independent of the weight of the body. Then we take a feather, and get very different results for acceleration of fall. Does this invalidate the 200.000 confirmations of the hypothesis?
The cosmos will be full of surprises the more we can measure and see. Unless the surprises become comparable in magnitude to the data supporting the standard model they will be studied looking for reasons for the exception, as with the feathers (aerodynamics) rather than invalidate statistically supported models (gravity in the thought experiment above).
Yes, Dr. Svalgaard, some people are beyond reach.
And, apparently you have no questions or objections to Dr. Anthony L. Peratt’s papers…
I suspect Science has further observations & measurements to make before the magnetic dynamics of the Milky Ways’s galactic core are fully known and understood.
The future stands before us.
Embrace the future.
cba (21:03:58) :
seems like one of the factors of distance indications for quasars is the lyman alpha forest. What is the response for the presence of the lyman alpha forest if a quasar is not at a tremendous distant.
In order to observe the Lyman alpha forest from the ground, the redshift must be 2 to 4: e.g. http://astro.berkeley.edu/~jcohn/lya.html But if one doesn’t believe in redshift being a distance indicator in the first place, then that argument doesn’t work well.
There is a much more direct method that does not rely on the distance ladder at all and which allows an absolute determination of the distance. Du to gravitational lensing we often observe multiple images of the same quasar. Quasars are very small in extent and often change brightness from month to month. The multiple images show the same fluctuations [because they show the same object] but not at the same time: one image may show the same fluctuations as another image but with a delay, say. The reason for this is that if the lensing object[s] is slightly off-center or not homogeneous across the object the light rays are bent differently [like looking though a glass of poor quality], and the light paths have thus different lengths. The bigger the object is in reality the bigger is the bending and the time delays in absolute terms. Since we can measure the extent of the object in angular terms [its apparent size], we can now compute its real distance combining the apparent size with the real size.
Leif Svalgaard (20:04:34) :
Evans asked: “Dr. Svalgaard, do you have a citation or link to support your claim that “the magnetic energy density in the Galactic core is incredibly small.”?
Dr. Svalgaard responded: “According to the article the field is 50 microGauss, that is 0.000,050 Gauss.”
Dr. Svalgaard: I reviewed the ScienceDaily article and this post, plus the links, therein.
There is no mention of “50 microGauss”. Now, it could be in the full paper published in Nature. Please provide the quote and an abstract citation from the Nature paper.
Otherwise, I have to conclude you made up that figure out of thin air.
James F. Evans (21:55:41) :
Otherwise, I have to conclude you made up that figure out of thin air.
This is a serious accusation. Perhaps a Danish proverb is applicable: ‘thief thinks everybody steals’.
Here is a link to their [free] preprint [so you don’t have to pay Nature $35]: http://arxiv.org/PS_cache/arxiv/pdf/1001/1001.1275v1.pdf
If you bump up the field to 100 microGauss [by a factor of two], the MED of 2,500 trillion times weaker becomes 600 trillion times weaker. Anyway you look at it, the magnetic energy density is incredibly weak.
You didn’t really need to have a link to the paper. The PR says that the field was at least 10 times stronger than in the rest of the Galaxy and it is well-known that the overall Galactic field is of the order of 3-7 microGauss.
Dr. Svalgaard:
Thank you for providing the link.
As I stated: “Now, it could be in the full paper published in Nature.”
And it was. My apologies. Thank you, again, for providing the link.
James F. Evans (22:51:42) :
My apologies.
Not accepted. You showed your true colors.
Dr. Svalgaard:
As you wish, however, I do appreciate your time and effort to provide the paper, not just for me, but for the website and other readers as the paper provides excellent discussion and is well worth reading and study.
I will study the paper.
Thank you for fulfilling my request.
James F. Evans (23:20:36) :
the paper provides excellent discussion and is well worth reading and study.
And I hope that you now realize how piddling and trifling the magnetic energy density in the Galaxy is, and that your notion of ‘intense’ magnetic fields there is not in accordance with observations. So you learned something and that is good.
Leif,
Other than to know they exist, I know little of them, but the lyman alpha forest shows myriads of these lyman alpha absorbing clouds at tremendous distances that are redshifted at all sorts of different red shift ‘velocities’, suggesting different cosmological distances. I would think that at least some of the quasars with gravitational lensing have been imaged in the uV/soft x-ray by satellite observatory and I’ve heard nothing of a blue shifted lyman alpha forest which should be present if these clouds were traveling at random velocities and directions rather than merely observing the effect of expansion.
While not having tried to put the pencil to the back of the envelope, I have wondered whether some of the gravitational lenses observed couldn’t be just plain old lensing caused by a difference in the index of refraction between the cloud and the intergalactic gas density. Of course that has to be a real guess considering the super ultra low density and temperature involved and even by the time one reaches atmospheric pressure and temperature the index of refraction of air is 1.00 with the diference being out another digit or two. I wouldn’t be suprised to find that the index of refraction for the clouds might be in the ballpark of what would be required for some of the observed multiimaged quasars, especially with vastly separated multiple lensing clouds.
cba (05:06:35) :
I’ve heard nothing of a blue shifted lyman alpha forest which should be present if these clouds were traveling at random velocities and directions rather than merely observing the effect of expansion.
The Doppler shifts from random movements [that do occur] would be MUCH smaller than the redshift due to expansion [or whatever] so would be completely swamped, and indeed none is observed.
the index of refraction for the clouds might be in the ballpark of what would be required for some of the observed multiimaged quasars, especially with vastly separated multiple lensing clouds.
The clouds are too thin for this to be important and when the lensing object is a giant elliptical galaxy without gas wouldn’t work anyway. But instead of thinking of light following straight lines [geodesics] in a curved space [near masses] one could assume that space was flat near masses but was imbued with an artificial refractive index at such places. The mathematics becomes the same and one can indeed demonstrate lensing using refraction as examples, e.g. http://doversherborn.org/~bridger/Astronomy/projects/radio/activities/demo/lensing/lensing.htm
A difference is that gravitational lensing is achromatic. Here is a good desrciption of the difference: http://astro.berkeley.edu/~cpma/3/sci.am.wambsganss.grav.lensing.pdf
Leif,
I’m nnot sure that a cold hydrogen gas isn’t achromatic also. We already know there’s pretty much a whole bunch of them way out there. Having a big fat elliptical right smack in the middle might sorta be a tell tale sign that it is substantially gravitational but aren’t there some cases where there is not an apparent galaxy, perhaps rather a cluster in the vacinity. Some have even speculated that Eddington’s original observations on GR during the eclipse may also have a refraction factor present that wasn’t accounted for then. I doubt it was nearly enough to explain things without GR though.
Personally, I prefer to think in simple terms and christ-awful symbols give me a headache. I prefer to think along the lines of photons having a mass = p/c being attracted to a gravitational body just like any other.