A New Model Without Dark Matter for the Rotation of Spiral Galaxies: The Connections Among Shape, Kinematics and Evolution by Mario Everaldo de Souza

Mario,

Not being well versed in cosmology, I can't comment intelligently on the correctness of the details set forth in your essay. That said, your model certainly looks interesting. Not made sufficiently clear to me, however, is how your essay addresses the theme of this competition: which of our basic physical assumptions are wrong? Has invoking the presence of dark matter to explain galactic formation achieved the status of a basic physical assumption? I honestly don't know the answer to this, but I think it would have been helpful if you had addressed this issue more explicitly. Thanks.

Good luck in the competition!

jcns

Dear JCN Smith,

Unfortunately, dark matter has gained the status of a basic assumption because of its implication in some cosmological models. But as I show in the essay this assumption is wrong and the explanation for the spiral structure is just the formation of the spiral arms by means of a continuous outflow of matter from the center of the spiral galaxy.

Mario,

A spiral galaxy formation is somewhat more complicated than a solar system formation, an obvious distinction being the distances involved within a time period. Our solar system planetary orbits would be a spiral if Newtonian gravity didn't accommodate "instantaneous action at a distance," which is simply due to the relatively short distances involved.

The large distances involved in a spiral galaxy displays the finite value of the "influence of gravity" velocity, and you should be able to calculate the approximate value of the velocity based upon the spiral form of a galaxy. The shape of the galaxy core will effect the shape of the spiral, as the barred core appears less like a point source to matter in the galaxy arms.

A number of assumptions have to be disposed of to arrive at a simpler explanation for spiral galaxy forms, dark matter being one of the assumptions. You can also think of a solar system formation being a fractal of a galaxy formation, a matter of scale. Also, keep in mind that it is assumed that the velocity of the influence of gravity is constant everywhere.

Assumptions are an attempt to form the shape of a puzzle piece to fit a piece to a large puzzle even though we don't know the final puzzle form. When future assumptions are based upon earlier assumptions, it is not difficult to start forming a Picasso-like puzzle result.

Hi Frank Makinson,

As I show in the essay, due to conservation of angular momentum, energy and mass, a certain amount of mass in the bulge, driven by radial forces (not well understood yet) leaves the bulge of the galaxy and takes a logarithmic spiral path which is formed because the ratio between the radial and tangential velocities of the mass remains constant as the mass goes away from the bulge. Of course, we can improve the model and include gravitational effects of the arms, but, as it is demonstrated in the essay, the first approximation yields already very good results proven by the fittting of several spiral galaxies. The essay did not present more fittings because the radial velocities of spiral galaxies is a quantity which was not used to be measured and is known only for some galaxies.

Dear Mario E. de Souza,

I just happily found your essay! Briefly, I'm not a physicist, so comprehending your essay will be rather difficult, but I'm also very interested in addressing the misconception of (at least) galactic dark matter. While I approach the issue as an information systems analyst (please bear with me), I urge you to read my essay, clumsily titled Inappropriate Application of Kepler's Empirical Laws of Planetary Motion to Spiral Galaxies Created the Perceived Galaxy Rotation Problem - Thereby Establishing a Galactic Presence for the Elusive, Inferred Dark Matter.

I've had fairly extensive discussions with several physicists that have done related work, including the development of (generally thin disk) modeling methods that can produce observed galactic rotational characteristics. I have noted a several relevant research reports in a "Supplemental Information" section in my essay For example, please see:

James Q. Feng and C. F. Gallo. "Modeling the Newtonian dynamics for rotation curve analysis of thin-disk galaxies." Res. Astron. Astrophys. 11 (December 2011): 1429. doi:10.1088/1674-4527/11/12/005. arXiv:1104.3236v4.

[unfortunately the doi link to this paper in my 'Suppl.' section is incorrect]

You may already be familiar with these works - if not you may find them quite interesting.

I think none of my references attempt to address the question of spiral arm formation and dynamics. I'll do my best to understand your explanation, since I also find the density wave theory conceptually 'unappealing'.

FYI - I thought I had once read of an observation indicating the presence of two SMBHs at opposing ends of a spiral galaxy's bar, but I can't seem to find it anymore. At any rate, it seems to me that a spiral galaxy could be formed by the high velocity interaction between two galaxies of similar mass could produce two 'comet-like' configurations headed by their SMBHs, eventually merging together in a planar spiral configuration. However, this seems to directly conflict with current theories and/or evidence...

I will continue to try to comprehend your work, and may ask for clarifications, etc. later. I am very pleased to see your essay and, while I understand J. C. N. Smith's appropriateness question, I certainly agree with you response. I think most of the FQXi community likes to take a very theoretical approach. I have yet to receive any comments regarding any of my essay's specific points, but then I'm an information systems analyst.

I certainly wish you well. I can also point your essay out to some other interested parties if you like.

Dear James T. Dwyer,

I thank you very much for your comments. The summary of my work is: the spiral structure is formed by the combination of rotation and continuous shedding of matter radially outwards from the center of the galaxy in a plane perpendicular to the angular momentum of the bulge.

Upon leaving the bulge a certain amount of mass of gas conserves its angular momentum and its kinetic energy, and because of these conservation laws, the mass is forced to follow a spiral path. Actually, considering the influence of the gravitational potential the curve described by the mass is a more complex curve. The spiral is obtained when the radial velocity at the bulge frontier is much larger than the escape velocity from the bulge. Unfortunately, I could not explain all this in the essay which has a limited scope.

With these conditions one obtains Danvar equation that had not yet been derived from Newtonian Mechanics. And moreover, one sees that the exponent of the equation is the ratio between the radial and tangential velocities of the mass of gas,establishing thus, a direct relation between shape and dynamics.

Only a couple of years ago researchers began measuring the radial velocities of the outflows in spiral galaxies.

Of course, the essay does not have the goal of explaining the origin of the radial outflow. Therefore, there is a lot to be explained.

Please, point the essay to other people that you know. Thank you.

Dear Mario E. de Souza,

Thanks very much for explaining. That must raise the question about 'bulgeless' spiral galaxies - are they thought to have exhausted their bulge material after forming the spirals?

Thanks,

Jim

Dear James T. Dwyer,

Yes, there is a direct relationship between age of a spiral galaxy and the size of its bulge. Young galaxies have large bulges and small arms, and old galaxies have small bulges and long arms (I mean arms with many turns). Actually, very young galaxies have very small nascent arms, just coming out. You got the idea.

Dear Mario E. de Souza,

Now I have to ask, presuming that the rotation curves of bulgeless spirals are also generally flat, or at least not compliant with Keplerian diminishing curves, what force would be responsible for their 'anomalous' peripheral rotational velocities?

The models I've become somewhat familiar with, as I understand, generally radially partition a galaxy's disk to determine partition mass from local rotational velocity.

As I see it, those models account for partition velocity resulting from local gravitational binding. In other words, peripheral masses are not expelled despite their high velocities because they are regionally bound to millions of neighboring objects, not independently orbiting any central mass or center of mass, as has been too often thought.

Sorry I can't explain very thoroughly or precisely - you'd have to review my references to get a more complete understanding...

Hi James T. Dwyer,

When the nucleus of the galaxy would stop shedding matter outwards the spiral arms would stop growing, that is all. But the matter that was shed would just keep going outwards. We have not yet observed this because galaxies have too much mass in their centers. Take a look at M51 which is an old galaxy. Its bulge is small an its arms have made some turns. It is still shedding matter outwards from its center.

Hi Mario,

Sorry if I'm becoming a pest. I found an interesting survey of large bulgeless spirals in doi:10.1088/0004-637X/723/1/54.

It would seem to me that if central outflows of material produced spiral arms and the process eventually stopped that either the outflow velocity would diminish or the spiral arm material would become increasingly sparse near the galactic center, in other words the spiral arms would spread apart from the center. I don't find any of those...

My (uninformed) skepticism is primarily due to the success of models that do not rely on outflow velocity to explain flat rotation curves. Perhaps I'm misinformed...

Thanks,

Jim

Hi,

Thank you for your comment. You raised a very important point which is not explicit in the essay.

Yes, when the Active Galactic Nucleus will become inactive the outflow should stop and the inner ends of the spiral arms will go away from the center and will get more and more apart from each other.

I did not find your survey on the net. Would you please send me the names of the galaxies? I mean their NGC, M, IC or UGC numbers. You should be carefull with what is called bulgeless spiral galaxy. I have never seen one of them. Bulgeless spirals are actually spirals with a very small bulge that becomes essentially the nucleus. For example, in a paper on bulgeless spirals C.J. Wacher et al., Ap.J. Vol. 618, p. 237, 2005 mention the following spirals with NGC numbers 300, 428, 1042, 1493, 2139, 3423, 7418, 7424 and 7793. NGC 300 has, actually, a very small bulge. NGC 428 has a very dim bulge that shows not much activity, and the arms ARE QUITE SEPARATED FROM THE BULGE. This goes in the direction of what you said above and shows that the essay is right. The other spirals of the paper have small bulges. Observe that these are late type spirals that have many turns.

The other models are not successful at all. There are only two main models: dark matter models and MOND. Dark matter is actually invisible matter of an extremely strange nature since it is constituted of heavy particles that do not interact with light and do not interact with baryons. That is why the possible candidates are the so-called WIMPS (weakly interacting massive particles). But WIMPS have almost been ruled out. Independently of this, dark matter does not make any sense at all due to the following reasoning. According to the model of dark matter the tangential velocities would have to go down slowly, but since in many spirals they are completely constant or even increase a little, there had to exist so much dark matter around a spiral that this dark matter would join with the dark matter of a nearby spiral and this would cause disruptions due to tidal forces. Besides, why dark matter would exist only in spirals and not in ellipticals? Just because ellipticals rotate less? As you see, it does not make sense. And recently the GALEX have found nascent spiral arms inside some elliptical galaxies!!!

The other important model is MOND that I rule out because according to MOND gravity is modified in a way to keep the tangential velocity constant across the spiral. But this modification of gravity does not act on larger scales and does not act in ellipticals.

Another alternative model is the model that says that spirals were originated from mergers in the early Universe. On this I recommend the enlightening paper Bulgeless Giant Galaxies challenge our picture of galaxy formation by hierarchical clustering by J. Kormendy et al., Ap. J. Vol 723, p. 54, 2010. Again, by bulgeless they mean small gulge. In their list of galaxies there is the galaxy NGC 6503 that has a very small bulge. It looks like that the inner ends of the spiral arms are away from the tiny bulge. The same happens with NGC 6946 mentioned in the paper.

Therefore, it looks like more and more that the idea of the essay is right.

Hi Mario,

Never mind about the survey link - I see it is the same paper by Kormendy et al that you recommend! I just perused it yesterday - I'll try to read it more thoroughly.

PLEASE read my essay, Inappropriate Application of Kepler's Empirical Laws of Planetary Motion to Spiral Galaxies Created the Perceived Galaxy Rotation Problem - Thereby Establishing a Galactic Presence for the Elusive, Inferred Dark Matter.

I attempt to explain how the galaxy rotation problem was erroneously conceived. I suspect some may be put off by my introductory narrative and my approach as a information systems analyst, but I think that if you carefully read through it you'll find some useful information. You should find that I wholeheartedly agree with your assessment of the well known approaches using dark matter or modified gravity - they are merely compensation for a gross misconception about gravitation evaluation.

In addition to the well known models relying on dark matter or MOND that you mention, there is also an unfortunately obscure group of physicists who have developed models more appropriately representing the actual configuration of galactic mass and proper methods of evaluating galaxy rotational dynamics. They have been successfully described observed rotational characteristics. A sampling of their research reports is included in my essay's "Supplemental Information" section, especially:

James Q. Feng and C. F. Gallo. "Modeling the Newtonian dynamics for rotation curve analysis of thin-disk galaxies." Res. Astron. Astrophys. 11 (December 2011): 1429. doi:10.1088/1674-4527/11/12/005. arXiv:1104.3236v4.

These models do not attempt to describe spiral galaxy development/evolution as yours does. I suspect you'll find them complementary, though.

I just started looking at the galaxies you referred to, and found in http://www.astrophotos.net/pages/GALAXIES/ngc%20428.htm an image captioned:

"NGC 428 is classified as type SBm with a surface brightness of 13.5. At 70 million light years, NGC 428 shows a tidal tail, a deformed morphology and starburst activity indicating a past encounter with another galaxy."

That assessment seems likely to me - I think the flippant tail is a telling feature. I'd caution against drawing any conclusions about the structure of galaxies that have been violently distorted through interaction with another galaxy.

I'll try to evaluate the other galaxies you mention later, as I'm old, lame & getting very tired...

My objective is to expose the myth of dark matter - the emperor has no clothes! [this may now be an obscure reference to the old children's story, "The Emperor's New Clothes"...]

Jim

P.S Regarding nascent spiral galaxies, there's an interesting article in Science News, Hubble Spots the Farthest Spiral Galaxy Ever Seen. It references a report in Nature Letters, High velocity dispersion in a rare grand-design spiral galaxy at redshift z = 2.18.

P.P.S. I did send a link to your essay and a brief description to ~20 physicists (see my "Suppl." section) and interested parties. So far I've only received a response from one theoretical physicist who only commented that he'd seen your paper...

Hi James,

I will take a look at your essay. The main idea that is wrong about galaxy formation is the idea of formation of a disk by rotation. In order to achieve this the rotational velocity had to be extremely high and thus it would completely disrupt the whole structure.

Hi Mario,

I hope you can answer a couple of very basic questions to help me to better comprehend your analysis.

I had understood that rotational velocities, for example, could be determined for spirals that presented some observational angle to us. In this way the rotational velocities of luminous disk objects could be derived from their peculiar spectrum shift relative to us.

That approach would not seem to be available for disks viewed face-on, since their rotational velocity would not be indicated by any redshift of light that we can detect, correct?

Since the galaxies shown in your paper all present a face-on view (the best for identifying the structure of spiral arms), how are 'lateral' velocities determined for what I presume are outflows directed along the disk plane, as are the spiral arms?

I have read of outflows and inflows of gas & dust moving perpendicularly in and out of the plane of a thin galactic disk to produce a thick disk...

Thanks very much in advance...

Hi James,

I only considerend in the essays galaxies that had the radial velocities known and also that could be easily fitted. The radial velocities (also known as outflow velocities) of galaxies that are not faqce-on have not yet been measured. But it is just a matter of making the right projections.

Yes, some galaxies have outflows perpendicular to the disk, but im most of them the outlows are not continuous and are not dense, and in some galaxies there are outflows of radiation. The Milky Way, for example, has two huge lobes of gamma radiation, like balloons, perpendicular to the disk. Read more on this just typing BUBBLES IN THE MILKY WAY on Google.

Hi Mario,

Thanks very much for the help. Perhaps I'm just too inquisitive, but do you know how 'lateral' or rotational velocity of face-on spirals is determined, since it would seem there'd be no significant spectrum shift of its EM emissions? I can easily understand how rotational velocity is determined for edge-on spirals, since the spectrum of their light that we receive is affected by their relative motion, but not face-on spirals.

Yep, the relativistic jets of AGNs and bubbles of ionized gas are very interesting. By the way, I just happened to notice that the rain bands in Hurricane Isaac (no relation) now sitting on top of New Orleans appear to correspond quite well to the arms of highly developed spiral galaxies. You might not be seeing it on your local weather programs, though...

As I understand, hurricanes are generally driven by rising hot air masses drawing up warm surface water. Could be analogous to the highly energetic central region of short-lived massive star formation and destruction, producing large volumes of dust and gas...

Hi James,

Actually, a real face-on is very rare. In general out line of sight makes an angle different from 90 degrees with the plane of disk of the galaxy. What researchers determine is a velocity field on the plane of the galaxy. On this I suggest that you read the important paper by J.E. Becjman, A. Zurita and J.C.V. Beltrán Kinematic measurements of gas and stars in spiral galaxies. Just type this title on Google.

A hurricane involves very different processes but we can see an important fact: the aggregation of gas particles into a rotating initial mass of gas produces a single thick arm which is subdivided in different parts.

Hi James,

I´m correcting a few typing mistakes I made in the last message. I meant OUR LINE OF SIGHT and on the paper I suggested one of the authors is J. E. Beckman and not J. E. Becjman.