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

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 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.

Hi Mario,

Thanks very much - this really is an excellent paper (to the extent I could comprehend). While it seems to be evaluating data that has already been high processed, to summarize, the 'simple' answer to my question might be that even slight differences in motion relative to the observer across a galaxy plane can be used to accurately indicate rotational velocities relative to the planar disk. Is that a generally correct summary?

I still don't understand how those very slight differences in redshift can be calibrated to determine specific velocities across the plane, but I'll trust that that's somehow reliably accomplished...

P.S. I also have problems speed typing - transposing letters. I noticed the 'j' key is right next to the 'k'...

P.P.S. In my essay, I seem to be criticizing Vera Rubin, but in fact I do appreciate her excellent work - I began my work with large computer systems in the early 1970s, so I understand that she didn't have a lot of help with analytical processing. I just identify the critical error leading to the false conclusion that has so enormously influenced astrophysics for the past 40 years.

Hi James,

You can trust the paper, these guys are good and many other astronomers. Astronomous, in general, are very meticulous.

Vera Rubin was and still is a great astronomer. You see, I have a great respect for the dark matter proposal. It did make a lot of sense at that time, actually, for quite some time. But the last word is always the word of Nature.

Hi Mario,

So did you read my essay and find it unconvincing?

Can you point me to some research that established that spiral galaxies should produce Keplerian rotation curves in any way similar to the Solar system's?

Do you not agree that while using two-body equations to evaluate the effects of gravity for planets orbiting the Sun provides generally useful approximations, they cannot be reasonably applied to n-body systems where n > billions of stars and other masses?

I'd certainly appreciate your feedback.

Hi James,

I have not read your essay yet. What do I do to read it?

All the models that assume the existence of dark matter in spiral galaxies consider that the motion of each star of the disc in a spiral galaxy follows a Keplerian orbit with a velocity equal to the square root of GM/r where G is the gravitational constant, M is the mass of the bulge and r is the distance of the star to the center of the galaxy. You get this relation by equating the centripetal force to the gravitational force. It is the same equation for a planet around the sun if M is the sun´s mass.

Actually, as I show in the essay the equation above cannot be applied to spiral

galaxies because of the radial velocity, that is, the orbit is not fixed.

Hi Mario,

Very good - I think we're in specific, if not general agreement...

The blog page is at http://fqxi.org/community/forum/topic/1419

The PDF can be found at http://fqxi.org/community/forum/topic/essay-download/1419/__details/Dwyer_FQXi_2012__Questionin_1.pdf

The main text is only 3 pages, with 2 more pages of Supplemental Info.

Links to all submitted essays can be viewed at http://fqxi.org/community/forum/category/31418?sort=date

They can be sorted by date, author last name, etc.

Thanks

Hi James,

Thanks for the information. I will take a look at your essay.

Mario

Original and interesting essay on an important subject where current theory is very incomplete. See my replies to James on my Blog. As an astronomer long studying galaxy evolution I do have some questions.

As I said to James I agree current interpretation is very poor and mainly wrong, including density waves 'forming' not blending spiral arms, and that we need fresh views if we're to unravel the complex puzzle. But consistency with real data not interpretation is essential, and any model must be judged by it's power to resolve a large tranche of anomalies without contradictions. I thus point out some apparent contradictions the length limit may have prevented you covering, so you can present for discussion.

1. All data from kinetic analysis consistently shows that the radial motion in older (redder population) galaxies from the disc to the core (accretion). The outflow is exclusively as 'jets' perpendicular to the disc, (both ways) from the AGN core. No flow is found along the arms of the bar, except low accretion to the core from the inner ends. This does not seem to match the core of your thesis. How are these findings explained?

2. How are bars formed in your model. (note that recent surveys confirm most galaxies have bars, just not all clearly visible).

3. Why is the average stellar age of the bar older than the age at the inner ends of the spiral arms in an open spiral?

4. You offer no evidence why Foyle a et al are 'wrong' when they do give evidence. Do you have anything specific?

5. Do you have a cause for the kinetic decoupling now found to be common?

I look forward to an interesting discussion. I have evolved an alternative model with some similarities which does seem to resolve the above and other questions, so it should be possible. Do follow the links in my blog, and read the end notes of my essay, dealing with consistent fundamental physics.

Best wishes.

Peter