Hidden galactic nuclei

Aug 10, 2012
Hidden galactic nuclei
The galaxy NGC 1068 with an active supermassive black hole at its nucleus. Astronomers studying similar extreme galaxies in the infrared have found that in many cases material obscuring the nucleus may be located over an extended region, and not confined in a small torus. Credit: NASA and the Chandra X-ray Observatory

(Phys.org) -- At the core of most galaxies including our own Milky Way is a massive black hole. Material falling into the environment of the black hole heats up, and can radiate dramatically, sometimes also powering the ejection of bipolar jets of rapidly moving charged particles. These so-called active galactic nuclei (AGN) are observed to have roughly two types of characteristics: bright, rapidly moving hot gas with dust emission features, or dust absorption with modest (or no) fast gas.

According to the "unified" model of AGN, these and most other variations in appearance are primarily due to the angle at which a galaxy and its central engine are seen. In the first case the galaxy is seen face-on, and fast-moving gas close to the black hole is clearly visible. In the latter, the whole galaxy as well as a torus of obscuring dust around the black hole are seen edge-on; the torus blocks our view of the fast-moving gas and absorbs infrared in characteristic dust features.

But is this simple model correct in all cases? CfA astronomers Andy Goulding, Bill Forman, Christine Jones, and Markos Trichas have undertaken a study of the origin of this infrared dust absorption feature. They specifically study the nature of the presumed torus: is it a small, uniform ring of dense material, a large extended structure of more diffuse material, or is it perhaps composed of many small ? The observed strength the infrared dust absorption is key to sorting out these differences.

The astronomers used the on the to examine the dust feature in all twenty nearby AGN having extremely large columns of neutral gas (Compton-thick AGN). The spectra provide quantitative measures of star formation as well as dust absorption. Writing in the , the scientists reach several important conclusions. They find that in a significant minority of cases the absorbing dust is spread over a region larger than a torus, in support of one variant of the unified model. They also caution that these kinds of AGN have unusually high levels of star-formation; searches for other extreme AGN that neglect star-formation signatures are likely to miss a significant population of the most heavily obscured AGN.

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Tuxford
1 / 5 (8) Aug 10, 2012
More cracks in the 'unified' model? Here is another data point to add to the cracks. Arp 220 includes the expulsion of massive winds from the core region, and high levels of star-formation, and dual core mother stars therein. (Oh, must be due to a collision...bs.)

http://phys.org/n...arp.html

Heavily obsured AGNs? So is this also an admission that AGN's may be more frequent than assumed? 2 2=.... Say it ain't so!
dtyarbrough
1 / 5 (8) Aug 10, 2012
If galaxies had super massive black holes at the center, orbital motion of stars would more closely resemble planetary systems. Read The Mystery of the Spiral Galaxies Explained http://www.scribd...xplained
yyz
3.9 / 5 (7) Aug 10, 2012
"Arp 220 includes the expulsion of massive winds from the core region, and high levels of star-formation, and dual core mother stars therein. (Oh, must be due to a collision...bs.)"

Obviously, *observations* of tidal tails in Arp 220 (which are indicative of gravitational encounters between two galaxies) are insufficient evidence for the past merger history in this object: http://arxiv.org/abs/1205.0302

And again, *observations* of the kinematics of CO in Arp 220 are insufficient evidence (in your eyes) of the past merger history of this galaxy. Those observations combined with computer simulations of possible merger scenarios, which match the observed morphology of Arp 220, are again insufficient to convince you of the merger origin of this object: http://arxiv.org/abs/1205.5638

Similarly, you find the starburst episode currently underway, the abnormally high SN rate, and the strong central winds from _two_ embedded, obscured nuclei as not indicative of a merger.

con't
sanita
1 / 5 (10) Aug 10, 2012
is it a small, uniform ring of dense material, a large extended structure of more diffuse material, or is it perhaps composed of many small dense clumps
Note that Milky Way galaxy contains more black holes in its center too. In steady state cosmology the active galactic nuclei are formed with condensation of dark matter from dark matter stars and they're converting their energy into matter instead.
yyz
3.5 / 5 (8) Aug 10, 2012
con't

Of course, if you are inclined to ignore all the *observational* evidence for a merger origin in Arp 220 I outlined above, your choice in believing a science fiction writer (LaViolette) who claims the B2 bomber utilizes antigravity technology and has personally received coded messages from an alien civilization by way of pulsars, seems par for the course. But totally devoid of science.
Q-Star
2.8 / 5 (11) Aug 10, 2012
@yyz

There seems to a lot odd ball ideas bandied about in the comment areas that try to pass as science. Not just this one article,,,, Science fiction writers should have their own forum to toss their "speculations" out in so they wouldn't feel inclined to have to "test" their musings here. It's very distracting to serious readers.
Tuxford
2.1 / 5 (7) Aug 10, 2012
@yyz
It is clear to me that you are much better at quoting papers, than in logical deduction. So defer to a higher authority. And take refuge in your encyclopedia. You are no closer to the truth. There are other explanations for 'tidal tales' for example. Just none that you would consider, as they are not yet listed in your encyclopedia.

jsdarkdestruction
4.3 / 5 (6) Aug 10, 2012
tuxford, reality is right outside your door. why not let it in for once and look at the world realistically instead of through laviolettes vision based on his science fiction fantasy? It's never too late to realize youve been decieved by your own fanatical beliefs in fairy tales,
yyz
4.3 / 5 (6) Aug 10, 2012
@Tuxford,

"It is clear to me that you are much better at quoting papers, than in logical deduction."

It is clear to me that you ignore actual observations that are compatible with a merger origin for Arp 220 and offer what? (published) interpretation of the observations presented in the two papers I linked? Do you (or Sanita, for that matter) have any recent references to observations that unambiguously point to a solitary, non-merger origin for Arp 220 (not including blogs, press releases, commentary, personal opinion, speculation etc., but published, peer-reviewed evidence wrt this particular galaxy)?

"There are other explanations for 'tidal tales' for example. Just none that you would consider, as they are not yet listed in your encyclopedia."

Yeah, and these explanations are in a book or DVD that LaViolette is willing to sell to the gullible. I guess the alien pulsar transmissions clued him in on that money stream.

Q-Star
1.8 / 5 (5) Aug 10, 2012
Hmmm, I wonder why it would be left out of the encyclopedia? Would merit have anything to do with that? They only have so much space to work with, so maybe they only put in the good stuff. (And rely on the internet for getting the TRUE stuff out to the scientific community.)

Of course if is outlandish enough, I suppose it might get an honorable mention, or pointed to as an object lesson on the quality of science. Ptolemy's model is in most of my encyclopedias, but I'm sure he would rather his model be left out of them entirely.
jsdarkdestruction
1 / 5 (3) Aug 11, 2012
@yyz
It is clear to me that you are much better at quoting papers, than in logical deduction. So defer to a higher authority. And take refuge in your encyclopedia. You are no closer to the truth. There are other explanations for 'tidal tales' for example. Just none that you would consider, as they are not yet listed in your encyclopedia.


his "higher authority" is alot better than yours. all you do is refer to laviolettes speculations(theory is not the right word for what laviolette puts out, theories are based on evidence and reality, not fantasy and magic codes in the stars.) so YOU are the one who started by deffering to your higher authority laviolette. youve got no right to criticise yyz for calling your nonsense out if you cant back it up w/o deffering to your "higher authority" too. You ever hear of the word hypocrite tuxford? It suits you well.
jsdarkdestruction
3 / 5 (6) Aug 11, 2012
"There are other explanations for 'tidal tales' for example. Just none that you would consider, as they are not yet listed in your encyclopedia."

Bullshit. Yyz is very impartial. if you could actually provide some sort of real proof that lavioltte was correct im sure yyz would be perfectly willing to take it into account and adjust what he thinks accordingly. you cant so he doesnt. The fault is completely yours here, not his. so stfu!
sanita
2 / 5 (4) Aug 11, 2012
if you could actually provide some sort of real proof that lavioltte was correct
LaViolette predicted in his thesis periodic flares of Milky Way core and now the recent Fermi observation support this view. They exhibits a burst of gamma ray and existence of gamma ray beams, pointing into various directions (this picture may be of your particular interest in this matter).
jsdarkdestruction
3.4 / 5 (5) Aug 11, 2012
http://phys.org/n...nter.htm

"These faint jets are a ghost or after-image of what existed a million years ago," said Meng Su, an astronomer at the Harvard-Smithsonian Center for Astrophysics (CfA), and lead author of a new paper in the Astrophysical Journal."

zephyr, How often are laviolette core ejection events? why do we only see evidence of the galactic core becoming active in the last million years once if it happens with regularity in laviolettes "theories"?
sanita
1.6 / 5 (7) Aug 11, 2012
Because IMO the black holes are behaving like common stars, just in greater scale: they condense from larger clouds (which include dark matter), they're evaporating their matter through radiation (including massive particles) until they become cool dense remnants. The compact event horizon (the huge gradient of space-time) doesn't penetrate the heavier particles than the axions and neutrinos. While the AGN are glowing continuously, the dense black holes are just puffing occasionally. Recently some axion based mechanism for it was proposed and even the most famous string theorist Ed Witten admitted openly evaporation of black holes from quantum reasons. IMO the mainstream physics will converge to La-Violatte ideas fast by itself and I'm just explaining it in advance.
sanita
1 / 5 (5) Aug 11, 2012
I often explain the behaviour of event horizon with total reflection mechanism: it reflects the particles formed with less sharp gradient, then the event horizon itself. Huge black hole have puffy event horizon, they do behave like so-called fuzzballs and they involve whole galaxy in which they're residing. During time a separation of matter occurs inside of galaxy like separation of oil and water mixture - the black hole will condense into dense core and the lightweight particles will form a galactic disk around it. The intensive evaporation of black hole will cease down gradually and it will become periodic or even irregular, because the compact event horizon enables the penetration of lightweight particles only and just during moments, when it gets "scratched" or "undulated" with some processes inside or outside of black holes. For example, when the black hole appears inside of large cloud of dark matter, it will start to radiate again, because of lower gradient of space-time.
sanita
1 / 5 (5) Aug 11, 2012
There is interesting aspects of so-called Schwarzchild limit, which predicts the radius of black hole, if we know its mass. But what prohibits us to consider the mass of the whole galaxy? Under such a situation the event horizon will be always formed - it will just remain widespread over the surfaces of all particles, which are forming the galaxy. In this sense we are living at the hyperdimensional surface of huge black hole - this surface just doesn't represents a compact manifold, but a hyperdimensional object. The classical event horizon in relativistic sense just determines the scope, in which this manifold becomes compact. Try to imagine a rough jagged object (a fruit of chestnut, for example), which penetrates the water surface partially. The hypothetical 2D creatures who live at such surface would perceive such a object as an array of circles, which gets more dense compact at its center.
Fleetfoot
5 / 5 (2) Aug 12, 2012
There is interesting aspects of so-called http://en.wikiped..._radius, which predicts the radius of black hole, if we know its mass. But what prohibits us to consider the mass of the whole galaxy?


That value is in the table on the page you cited, try reading them as well as citing.

Under such a situation the event horizon will be always formed - it will just remain widespread over the surfaces of all particles, which are forming the galaxy.


Nope, the radius is given as 0.2 light years so you would only get an event horizon if all the mass of the galaxy is within a sphere of that radius.
Fleetfoot
5 / 5 (2) Aug 12, 2012
If galaxies had super massive black holes at the center, orbital motion of stars would more closely resemble planetary systems. Read The Mystery of the Spiral Galaxies Explained http://www.scribd...xplained


Sag A* has a mass of 4.3 million Msun, the galaxy is ~300 billion Msun, so the central object is only 0.0014% of the total mass.