Spiral and Disk Galaxies are controlled by single parameter. What and How?

[Saul]

This is a significant discovery that something is fundamentally controlling and ordering the properties of spiral and disk gaseous galaxies. Elliptical galaxies have no gas and no star formation.

The question is not only what but how is the unknown parameter controlling spiral and disk galaxy evolution and properties.

This appears to me to be a discovery as significant as the Hertzsprung-Russell diagram which led to the formation theory of stars.

http://en.wikipedia.org/wiki/Hertzsprung–Russell_diagram

http://arxiv.org/abs/0811.1554

http://www.nature.com/nature/journal/v455/n7216/abs/nature07366.html

Galaxies (my comment: Spiral and disk) appear simpler (my comment tightly controlled) than expected

Galaxies are complex systems the evolution of which apparently results from the interplay of dynamics, star formation, chemical enrichment and feedback from supernova explosions and supermassive black holes1. The hierarchical theory of galaxy formation holds that galaxies are assembled from smaller pieces, through numerous mergers of cold dark matter2, 3, 4. The properties of an individual galaxy should be controlled by six independent parameters including mass, angular momentum, baryon fraction, age and size, as well as by the accidents of its recent haphazard merger history. Here we report that a sample of galaxies that were first detected through their neutral hydrogen radio-frequency emission, and are thus free from optical selection effects5, shows five independent correlations among six independent observables, despite having a wide range of properties. This implies that the structure of these galaxies must be controlled by a single parameter, although we cannot identify this parameter from our data set. Such a degree of organization appears to be at odds with hierarchical galaxy formation, a central tenet of the cold dark matter model in cosmology6.

If, as we have argued, galaxies come from at most a six-parameter set, then for gaseous galaxies to appear as a one-parameter set, as observed here, the theory of galaxy formation and evolution must supply five independent constraint equations to constrain the observations. This is such a stringent set of requirements that it is hard to imagine any theory, apart from the correct one, fulfilling them all. For instance, consider heirarchical galaxy formation in the dark matter model, which has been widely discussed in the literature3,4. Even after extensive simplification, it still contains four parameters per galaxy: mass, spin, halo-concentration index and epoch of formation. Consider spin alone, which is thought to be the result of early tidal torquing. Simulations produce spins, independent of mass, with a log-normal distribution. Higher-spin discs naturally cannot contract as far; thus, to a much greater extent than for low-spin discs, their dynamics is controlled by their dark halos, so it is unexpected to see the nearly constant dynamical-mass/luminosity ratio that we and others14 actually observe. Heirarchical galaxy formation simply does not fit the constraints set by the correlation structure in the Equatorial Survey.

More generally, a process of hierarchical merging, in which the present properties of any galaxy are determined by the necessarily haphazard details of its last major mergers, hardly seems consistent with the very high degree of organisation revealed in this analysis. Hierarchical galaxy formation does not explain the commonplace gaseous galaxies we observe. So much organization, and a single controlling parameter which cannot be identified for now argue for some simpler model of formation. It would be illuminating to identify the single controlling galaxy parameter, but this cannot be attempted from the present data.

It is natural to ask why this fundamental line was not discovered before. To some extent it was because even the pioneers24,25 and others26,27,28 working with small numbers of optically selected spirals could reduce six observables to two; one relating to size, one to morphology. The strong optical selection effects, which hamper optical astronomers in detecting and measuring galaxies whose surface brightnesses are barely brighter than the sky5,29, disguised galaxies’ simplicity.

 

[Chalnoth]

From what I hear batted around by those studying these things, those within the field seem to currently consider AGN feedback to be the primary mechanism that distinguishes spiral behavior from elliptical behavior. Though it's also worth mentioning that galaxies are understood to be incredibly complex beasts, and there are sure to be many other factors at work as well.

 

[Saul]

From what I hear batted around by those studying these things, those within the field seem to currently consider AGN feedback to be the primary mechanism that distinguishes spiral behavior from elliptical behavior. Though it's also worth mentioning that galaxies are understood to be incredibly complex beasts, and there are sure to be many other factors at work as well.

Feedback can not explain any observation. There are presentations concerning these anomalies that are starting to make jokes about the feedback attempt. (i.e. It seems it may not be physically viable. If it is not that is a triumph for scientific analysis as it important not to parameter fit an incorrect mechanism as it stops progress.)

Feedback was also used in an attempt to explain the discrepancy between the observed variance of rotational velocity of spiral galaxies with radius vs what the models predicted with dark matter. (The problem is the dark matter models predict the spiral galaxy's rotational velocity should change as 1/radius of the galaxy as one move from the centre of the galaxy to the galaxy's outer radius, particularly as one reaches the centre of the galaxy. Observationally the rotational velocity of the spiral galaxy changes linearly with radius. The models predict galaxy bulges that are too large (this is related to the rotational velocity observation) and the number of satellite galaxies that is predicted is higher than what is observed by a factor of 10. There are other problems.)

As there are groups of anomalies concerning spiral galaxy & BHs properties and the evolution of those properties with redshift it seems likely there may be a fundamental model explanation for all of the anomalies. i.e. The correct mechanism will explain the entire set and may eliminate other assumed mechanisms which are starting to have trouble. (I will start another thread sometime to elaborate.)

The logical approach is to look to see if there are other observational anomalies concerning the spiral galaxies, spiral galaxy stars, BH holes, BH and Spiral galaxy property evolution wiht redshift looking for a hint as to what the correct fundamental model might be.

 

[Saul]

I am not sure people will understand why this observation is interesting or why it is placed in a thread that discusses the observational finding that spiral galaxy properties are tightly controlled and there is currently no physical explanation for why spiral galaxy properties are tightly control and interrelated.

Perhaps a specific example might help to illustrate the severity of the puzzles. Try to explain the observations using standard assumed models.

Spiral galaxy luminosity for example is tightly related to the galaxy in questions' rotational velocity. (This relationship is called the Tully-Fisher luminosity vs rotational relationship) Also the galaxies mass is tightly related to the galaxies rotational velocity (That relationship is called the Tully-Fisher Baryonic mass to rotational relationship.)

Now think about what is observed. How could a galaxy's rotational velocity change with time? Galaxies are getting large with higher redshift and those that have most rotational velocity are the most luminous and have the most mass. What model are you assuming (i.e. Physically what are you assuming is happening to the spiral galaxy in question? What is happening to the spiral galaxy to increase its rotational velocity? When you are increasing the rotational velocity of the spiral galaxy how do you keep a close relationship to the galaxy's luminosity?

The ratio of the BH hole's mass to the ratio of BH hole's Host galaxy get less with redshift by a factor of 7 from z=0 to z=3. Gets less by a factor of 7. Gets less by a factor of 7.

Either the BH has lost mass which is assumed to be impossible or the galaxies have gained mass or BH mass formation was more efficient at Z=3 than Z=0 in a manner that changes with in a straight line with redshift.

I am placing this observation in this thread because it concerns an anomaly concerning mass. Specific astronomical objects have more or less gas. Gas is mass.

http://journals.cambridge.org/action/displayAbstract?fromPage=online&aid=7790506

Co-Evolution of Supermassive Black Holes and Their Host Galaxies


We study the evolution of the MBH/Mhost relation up to z = 3 for a sample of 96 quasars with known host galaxy luminosities. Black hole masses are estimated assuming virial equilibrium in the broad-line regions, while the host galaxy masses are inferred from their luminosities. With this data, we are able to pin down the evolution of the MBH/Mhost relation over 85% of the age of the universe. While the MBH/Lhost relation remains nearly unchanged, taking into account the aging of the stellar population, we find that the MBH/Mhost ratio (Γ) increases by a factor ~ 7 from z = 0 to z = 3. We show that the evolution of Γ is independent of radio loudness and quasar luminosity. We propose that the most massive black holes, in their quasar phase at high-redshift, become extremely rare objects in host galaxies of similar mass in the local universe.

This is a public link to the same paper.

http://arxiv.org/PS_cache/arxiv/pdf/0911/0911.2988v1.pdf

The quasar MBH–Mhost relation through Cosmic Time
II – Evidence for evolution from z = 3 to the present age

In Figure 2 MBH, Mhost and their ratio Γ are plotted all together as a function of redshift. The linear best fit of log Γ is: log Γ = (0.28 ± 0.06) z − (2.91 ± 0.06) suggesting that galaxies with similar stellar masses harbour BHs approx. 7 times more massive at z = 3 than galaxies at z = 0.

 

[Chalnoth]

Spiral galaxy luminosity for example is tightly related to the galaxy in questions' rotational velocity. (This relationship is called the Tully-Fisher luminosity vs rotational relationship) Also the galaxies mass is tightly related to the galaxies rotational velocity (That relationship is called the Tully-Fisher Baryonic mass to rotational relationship.)

Now think about what is observed. How could a galaxy's rotational velocity change with time?

I don't understand why this would be terribly surprising. Spiral galaxies tend to have lots of interstellar dust, dust which also feeds star formation. The dust itself feeds star formation, and also adds a friction term that would relate to the galaxy's rotational velocity. The existence of a direct relationship between rotational velocity and luminosity, then, is likely to be telling us something interesting about the nature of the gas physics in these galaxies.

The ratio of the BH hole's mass to the ratio of BH hole's Host galaxy get less with redshift by a factor of 7 from z=0 to z=3. Gets less by a factor of 7. Gets less by a factor of 7.

More likely what you're seeing here is a selection effect. It's easier to observe and measure smaller black holes that are nearby. The only ones that we can see at large distances are the ones that are larger. I sincerely doubt that this will turn out to be a real relationship.

 

[Saul]

I don't understand why this would be terribly surprising. Spiral galaxies tend to have lots of interstellar dust, dust which also feeds star formation. The dust itself feeds star formation, and also adds a friction term that would relate to the galaxy's rotational velocity. The existence of a direct relationship between rotational velocity and luminosity, then, is likely to be telling us something interesting about the nature of the gas physics in these galaxies.


More likely what you're seeing here is a selection effect. It's easier to observe and measure smaller black holes that are nearby. The only ones that we can see at large distances are the ones that are larger. I sincerely doubt that this will turn out to be a real relationship.

The dust itself feeds star formation, and also adds a friction term that would relate to the galaxy's rotational velocity.

What friction factor increases the rotational velocity of galaxies? Explain the friction factor. Angular momentum is conserved. There must be a torque to create the increase rotation. Try mergers. The problem however with mergers is in simulations mergers of spiral with spiral creates an elliptical galaxies. The fraction of spiral galaxy to elliptical galaxy stays roughly constant with redshift at 70% spiral and 30% elliptical.

More likely what you're seeing here is a selection effect. It's easier to observe and measure smaller black holes that are nearby. The only ones that we can see at large distances are the ones that are larger. I sincerely doubt that this will turn out to be a real relationship.

There are other papers on the same subject. I have not heard anyone proposing that it is do to selection factor.

Note the host galaxy's mass increases relative to the BH by a factor of 7 from z=3 to z=0. There must be massive amounts of new gas that enters the galaxy and does not increase the mass of the BH, or there must be mergers that increases the mass of the galaxy but not the mass of the BH or the BH must be losing mass to the its host galaxy which we believe is physically not possible.

As noted above the problem with mergers is simulations show a merger of spiral to spiral creates a elliptical galaxy.

Note also there is the requirement to provide a physical explanation of Disney et al's discovery that spiral and disk galaxy properties are tightly control by a single mechanism and that mechanism also increases rotational velocity.

 

[Chalnoth]

What friction factor increases the rotational velocity of galaxies?

Generally when a gravitational system loses energy through friction, it collapses inward, which causes it to speed up its rotation.

There must be massive amounts of new gas that enters the galaxy and does not increase the mass of the BH, or there must be mergers that increases the mass of the galaxy but not the mass of the BH or the BH must be losing mass to the its host galaxy which we believe is physically not possible.

Ah, well, that actually makes sense. There are two possibilities that I can see:
1. Most of the mergers are with smaller galaxies that don't disturb the spiral structure.
2. Galaxies, if they have a significant amount of interstellar dust remaining, tend to revert to a spiral shape after mergers.

I suspect the first is the far more likely option of the two.

As noted above the problem with mergers is simulations show a merger of spiral to spiral creates a elliptical galaxy.

Only simulations of mergers with nearly equal-mass galaxies.

Note also there is the requirement to provide a physical explanation of Disney et al's discovery that spiral and disk galaxy properties are tightly control by a single mechanism and that mechanism also increases rotational velocity.

A single parameter is not a single mechanism. The two are different concepts, and probably says more about the dynamics, likely due to baryonic physics combined with AGN feedback, that lead galaxies to one of two potential end fates than anything else.

 

[Saul]

Generally when a gravitational system loses energy through friction, it collapses inward, which causes it to speed up its rotation.

You are thinking about a star not a galaxy. When a rotating cloud that has angular momentum collapses the cloud's rotational energy is conserved and the rotational velocity of the resultant; stars and planets increases.

For this case the galaxies in question increase in mass is due to the in falling of new gas clouds. (The galaxies increase in mass from z=3 to z=0 by a factor of 7, in relationship to their black holes.). (i.e. The initial cloud that formed the galaxy is the source of the galaxy's angular momentum. Gas clouds do not de facto have angular momentum unless they are part of a rotating spiral galaxy which has angular momentum. There are clusters of stars that formed from gas clouds that did not rotating in regions about our galaxy that do not have angular momentum.)

Comment:
The source of the spiral and disk's angular momentum is hypothesized to be torque of two different gas clouds. That mechanism does not explain how spiral galaxies can increase their rotational velocity as they grow. Compare a spiral galaxy to an elliptical galaxy.

What we would expect is all galaxies should be elliptical. Multiple merger events of spiral galaxies should create elliptical galaxies. Gas clouds and spiral galaxies fall into the spiral galaxy from random angles. The resultant is a group of stars (elliptical galaxy) that has typically no significant net rotation. (i.e. Elliptical galaxies' stars rotate in clockwise and counter clockwise about up to three rotational axises so net sum of the angular momentum cancels.

Subsequent gas clouds that falls into the galaxy's disk gas cloud heats up the disk gas but does not increase the rotational velocity of the disk. (There is friction which heats up the gas and dissipates the kinetic energy of the in falling gas cloud but no increase in angular momentum. Angular momentum is conserved.) There is hence no increase in rotational velocity.

 

[Chalnoth]

You are thinking about a star not a galaxy. When a rotating cloud that has angular momentum collapses the cloud's rotational energy is conserved and the rotational velocity of the resultant; stars and planets increases.

For this case the galaxies in question increase in mass is due to the in falling of new gas clouds. (The galaxies increase in mass from z=3 to z=0 by a factor of 7, in relationship to their black holes.). (i.e. The initial cloud that formed the galaxy is the source of the galaxy's angular momentum. Gas clouds do not de facto have angular momentum unless they are part of a rotating spiral galaxy which has angular momentum. There are clusters of stars that formed from gas clouds that did not rotating in regions about our galaxy that do not have angular momentum.)

No, it's a general statement. It comes from the fact that a random walk diverges from the zero mean by the square root of the number of steps. So when you produce a gas cloud by starting from a big, diffuse entity that collapses inward, on average you get something with quite a bit of angular momentum and noticeable rotation.

There's nothing fundamentally different about this situation versus producing a large galaxy through a merger of a large number of small ones: each one will add a random angular momentum that will, in general, not be zero, and not add to zero. All that you need is some friction to transmit the angular momentum from the incoming gas clouds to the rest of the galaxy.

Of course, the devil is in the details, and it may well be difficult to get the right amount of rotation. But the simple fact of galaxies increasing in apparent angular momentum with mergers doesn't surprise me in the least.

Comment:
The source of the spiral and disk's angular momentum is hypothesized to be torque of two different gas clouds. That mechanism does not explain how spiral galaxies can increase their rotational velocity as they grow. Compare a spiral galaxy to an elliptical galaxy.

What we would expect is all galaxies should be elliptical. Multiple merger events of spiral galaxies should create elliptical galaxies. Gas clouds and spiral galaxies fall into the spiral galaxy from random angles. The resultant is a group of stars (elliptical galaxy) that has typically no significant net rotation. (i.e. Elliptical galaxies' stars rotate in clockwise and counter clockwise about up to three rotational axises so net sum of the angular momentum cancels.

No, it's a random walk. In the ensemble average the angular momentum may be zero, but individual galaxies will definitely not have zero angular momenta. The difference is that the elliptical galaxy typically has very little dust, which means very little friction, so that you just don't see the angular momentum because the stars aren't forced to line up along the direction of average rotation.

 

[Max™]

I get the impression that the "no significant net rotation" is being misinterpreted, a tub full of moving marbles may not exhibit a preferred rotational axis, but it is hardly sitting still.

We can observe that dusty spiral galaxy effectively transfers so much rotational motion along the same axis, why wouldn't a less dusty elliptical be more randomized?

 

[Saul]

No, it's a general statement. It comes from the fact that a random walk diverges from the zero mean by the square root of the number of steps. So when you produce a gas cloud by starting from a big, diffuse entity that collapses inward, on average you get something with quite a bit of angular momentum and noticeable rotation.

No, it's a random walk. In the ensemble average the angular momentum may be zero, but individual galaxies will definitely not have zero angular momenta. The difference is that the elliptical galaxy typically has very little dust, which means very little friction, so that you just don't see the angular momentum because the stars aren't forced to line up along the direction of average rotation.

You comment is not correct. Because you live on a rotating planet, that orbits a star, in a rotating spiral galaxy you assume gas clouds when they collapse will always rotate which is not correct.

The gas cloud will only rotate if it had initial angular momentum (i.e. It was rotating before the collapse). Angular momentum is conserved.

What you are describing: A gas cloud that does not have angular momentum suddenly as it collapses develops angular momentum is not physically possible. Just as the water molecules in a glass of water do not suddenly jump out of the glass. i.e. One cannot command all the molecules to change direction or to move about an axis. Think of the trillions of atoms and molecules moving randomly and each individual collision of atom or molecule with atom or molecule. Each collision is from a random direction. The resultant is also random.

You use the word random in your explanation but do not accept the logical consequences of the word random when applied to trillions of individual gas atoms and molecules. Collapsing gas clouds only rotate when they collapse if they where rotating before collapsing.

 

[Jonathan Scott]

Collapsing gas clouds only rotate when they collapse if they where rotating before collapsing.

Next you'll be telling us that bath water doesn't form a vortex above the plug hole.

You're over-stating this.

Small irregularities in velocity and momentum at a large radius give rise to amounts of angular momentum which may appear insignificant, but when the same material is reduced to a much smaller radius, it becomes statistically improbable that it does NOT end up spinning.

Perhaps you're expecting the "randomness" to smooth this out. If you have a larger sample of something random, then it's usually true that the relative deviation from the mean decreases, but it can't simply be assumed to be zero.

 

[Chalnoth]

You comment is not correct. Because you live on a rotating planet, that orbits a star, in a rotating spiral galaxy you assume gas clouds when they collapse will always rotate which is not correct.

The gas cloud will only rotate if it had initial angular momentum (i.e. It was rotating before the collapse). Angular momentum is conserved.

Well, in a sense. But you missed my point. If you take a collection of atoms in a gas cloud, and completely randomize their trajectories, each will provide a random contribution to the overall angular momentum. I'd have to work out how this goes in three dimensions, but it's basically going to end up that the typical angular momentum of a gas cloud will be some number times the typical angular momentum of a single particle times the square root of the number of particles in the gas cloud.

So, as long as the gas cloud starts out much bigger than its eventual collapsed size, you are guaranteed to get noticeable rotation. Now, granted, obviously there had to be some average rotation to begin with, but my point here is that before the gas cloud started to collapse, its rotation wouldn't have been noticeable. It's only once it has collapsed that you are left with a significant amount of rotation.

 

[Saul]

Puzzle 1: Spiral galaxies are simple. i.e. All the different galaxy parameters for disk/spiral galaxies are patterned indicating that they are controlled by something. What and How?

Disney et al finding that spiral galaxies' parameters are tightly controlled by some unknown parameter and or mechanism was not expected and currently has no explanation.

Puzzle 2: What causes spiral/disk galaxies to form as opposed to elliptical galaxies and visa versa?

Connected with Disney's finding is the problem of explaining the two different galaxy general galaxy types: disk/spiral and elliptical

Puzzle 3: Ratio of Disk/Spiral galaxy's BH mass to Host galaxy's mass increases by a factor of 7. Why?

The finding that the ratio of the spiral/disk galaxy's mass to the ratio of the host's galaxy's Black Hole (BH) increases by a factor of 7 from z=3 to z=0 also does not have an explanation. As I noted above either the host galaxy's BH's mass must be getting less with time which we believe is not possible or the mass of all disk/spiral galaxies must be increasing with time in a manner that does not increase the mass of the host galaxy's BH.

Puzzle 4: Curious non random angular momentum oddities in the Milky Way. Angular momentum is conserved. What is causing the observed angular momentum change with time?
If you look into the observations for the Milky Way at detail what is observed is not random. There are puzzling indications of some mechanism that affects rotational velocity. For example is a rotation difference between the thick disk which is older than the thin disk which contains the gas. (The thick disk rotates at a slightly lower speed.) It looks as if something is creating gas in the galaxy and increasing its angular velocity, in the galaxy's disk.

Puzzle 5: Sun's movement outward in the Galaxy. Is this a one of or are other stars moving outward in the galaxy? See puzzle 4. If stars are moving, next question, are all stars the same? Could some stars move outward and others not?

Curiously based on an analysis of solar metallicity it has been shown that the sun has moved outward in the Milky Way by a 1000 light years since it was formed. This observation is alleged to be due fortuitous interaction in the original cluster of stars that the sun was formed in. If you remember it was been found that spiral/disk galaxies at high redshift are massive but compact. Some unknown force is causing the spiral/disk galaxy to expand.

Puzzle 6: Spiral galaxy's rotation anomaly. What is causing that observation? Note all efforts to directly detect dark matter in laboratory experiments have failed. If Shanks' finding of an error in the interpretation of the CMB analysis is correct there is no longer support for the existence of dark matter based on patterns in the CMB.

As noted based on observations the spiral galaxy's rotational velocity changes linearly with radius. Dark matter simulations predict spiral galaxy's rotational velocity should change as 1/radius of the galaxy decreasing as one reaches the center of the galaxy there by creating a central galaxy bulge that is large than observed.Back to thinking about the observations. This comment concerns the two different galaxy types Spiral and Elliptical.

Collisions of spiral with spiral should create an elliptical galaxy. Observationally however the percentage of spiral to elliptical remains almost constant with redshift (time) at 70% spiral to 30% elliptical.

Extragalactic Astronomy and Cosmology An Introduction by Peter Schneider https://www.amazon.com/dp/3540331743/?tag=pfamazon01-20

page 92:

It was once believed that ellipticals contained neither gas or dust, but these components have been found, though at much lower mass-fraction than in spirals. … Many of the normal ellipticals contain visible amounts of dust partially manifested as a dust disk. The metallicity of ellipticals … increases towards the galaxy center, as derived from color gradients.

…. In addition, many ellipticals show a so-called isophote twist: the orientation of the semi major axis for the isophote changes with radius. This indicates that elliptical galaxies are not spheroidal, but triaxial system(or that there is some intrinsic twist of their axes.)

http://www.encyclopedia.com/doc/1O80-isophote.html

isophote A line joining points with the same surface brightness on a diagram or an image of a celestial object such as a galaxy or nebula. The surface brightness is usually measured in magnitudes per square arc second. The sum of all the light within a given isophote is termed the isophotal magnitude.

 

[Chalnoth]

Puzzle 1: Spiral galaxies are simple. i.e. All the different galaxy parameters for disk/spiral galaxies are patterned indicating that they are controlled by something. What and How?

Disney et al finding that spiral galaxies' parameters are tightly controlled by some unknown parameter and or mechanism was not expected and currently has no explanation.

Puzzle 2: What causes spiral/disk galaxies to form as opposed to elliptical galaxies and visa versa?

Connected with Disney's finding is the problem of explaining the two different galaxy general galaxy types: disk/spiral and elliptical

Puzzle 3: Ratio of Disk/Spiral galaxy's BH mass to Host galaxy's mass increases by a factor of 7. Why?

The finding that the ratio of the spiral/disk galaxy's mass to the ratio of the host's galaxy's Black Hole (BH) increases by a factor of 7 from z=3 to z=0 also does not have an explanation. As I noted above either the host galaxy's BH's mass must be getting less with time which we believe is not possible or the mass of all disk/spiral galaxies must be increasing with time in a manner that does not increase the mass of the host galaxy's BH.

Puzzle 4: Curious non random angular momentum oddities in the Milky Way. Angular momentum is conserved. What is causing the observed angular momentum change with time?
If you look into the observations for the Milky Way at detail what is observed is not random. There are puzzling indications of some mechanism that affects rotational velocity. For example is a rotation difference between the thick disk which is older than the thin disk which contains the gas. (The thick disk rotates at a slightly lower speed.) It looks as if something is creating gas in the galaxy and increasing its angular velocity, in the galaxy's disk.

Puzzle 5: Sun's movement outward in the Galaxy. Is this a one of or are other stars moving outward in the galaxy? See puzzle 4. If stars are moving, next question, are all stars the same? Could some stars move outward and others not?

Curiously based on an analysis of solar metallicity it has been shown that the sun has moved outward in the Milky Way by a 1000 light years since it was formed. This observation is alleged to be due fortuitous interaction in the original cluster of stars that the sun was formed in. If you remember it was been found that spiral/disk galaxies at high redshift are massive but compact. Some unknown force is causing the spiral/disk galaxy to expand.

Puzzle 6: Spiral galaxy's rotation anomaly. What is causing that observation? Note all efforts to directly detect dark matter in laboratory experiments have failed. If Shanks' finding of an error in the interpretation of the CMB analysis is correct there is no longer support for the existence of dark matter based on patterns in the CMB.

As noted based on observations the spiral galaxy's rotational velocity changes linearly with radius. Dark matter simulations predict spiral galaxy's rotational velocity should change as 1/radius of the galaxy decreasing as one reaches the center of the galaxy there by creating a central galaxy bulge that is large than observed.

As I've said previously, interactions with the interstellar gas are the most likely explanation for most of these, with AGN feedback primarily affecting the amount of gas within the galaxy (and thus the differentiation between elliptical/spiral galaxies). Getting the baryonic physics correct is absurdly difficult, and it shouldn't be too surprising that many of the subtle details of our simulations don't yet match up with reality.

And no, Shanks' finding doesn't impact the evidence for dark matter in the CMB.

 

[Saul]

Next you'll be telling us that bath water doesn't form a vortex above the plug hole.

You're over-stating this.

Small irregularities in velocity and momentum at a large radius give rise to amounts of angular momentum which may appear insignificant, but when the same material is reduced to a much smaller radius, it becomes statistically improbable that it does NOT end up spinning.

Perhaps you're expecting the "randomness" to smooth this out. If you have a larger sample of something random, then it's usually true that the relative deviation from the mean decreases, but it can't simply be assumed to be zero.

Bath water forms a vortex because the planet rotates.

The resultant of collapsing gas clouds will not rotate if it did not have initial angular momentum.

http://www.loc.gov/rr/scitech/mysteries/coriolis.html

The Coriolis Effect is the observed curved path of moving objects relative to the surface of the Earth. Hurricanes are good visual examples. Hurricane air flow (winds) moves counter-clockwise in the northern hemisphere and clockwise in the southern hemisphere. This is due to the rotation of the Earth. The Coriolis force assists in setting the circulation of a hurricane into motion by producing a rightward (clockwise) deflection that sets up a cyclonic (counterclockwise) circulation around the hurricane low pressure.

 

[Saul]

Well, in a sense. But you missed my point. If you take a collection of atoms in a gas cloud, and completely randomize their trajectories, each will provide a random contribution to the overall angular momentum. I'd have to work out how this goes in three dimensions, but it's basically going to end up that the typical angular momentum of a gas cloud will be some number times the typical angular momentum of a single particle times the square root of the number of particles in the gas cloud.

So, as long as the gas cloud starts out much bigger than its eventual collapsed size, you are guaranteed to get noticeable rotation. Now, granted, obviously there had to be some average rotation to begin with, but my point here is that before the gas cloud started to collapse, its rotation wouldn't have been noticeable. It's only once it has collapsed that you are left with a significant amount of rotation.

If there is no net angular momentum of the initial gas cloud there will be no net angular momentum after collapse.

You are appealing to complexity (i.e. The vast number of particles and there motions.) to create net angular momentum which is not possible. Angular momentum is conserved.

http://en.wikipedia.org/wiki/Angular_momentum

Just as water does not jump out of glass as the water molecules move randomly and the after collisions continue to move randomly.

 

[Chalnoth]

Bath water forms a vortex because the planet rotates.

Nope. It's got nothing to do with that. The coriolis force from the Earth's rotation is insignificant on those scales. It is significant for hurricanes (and other large weather systems) due to their size. It is significant for tornadoes due to their high wind speeds. But it isn't significant for things like toilets and bathtubs.

The resultant of collapsing gas clouds will not rotate if it did not have initial angular momentum.

And gas clouds will, in general, not have zero angular momentum, even with fully-randomized initial conditions.

 

[Saul]

As I've said previously, interactions with the interstellar gas are the most likely explanation for most of these, with AGN feedback primarily affecting the amount of gas within the galaxy (and thus the differentiation between elliptical/spiral galaxies). Getting the baryonic physics correct is absurdly difficult, and it shouldn't be too surprising that many of the subtle details of our simulations don't yet match up with reality.

And no, Shanks' finding doesn't impact the evidence for dark matter in the CMB.

The problem is that simulations produce what is observed for an elliptical galaxy. A complicate object that has multiple rotational axises and that has stars that rotating in multiple directions about galaxy. The point is galactic collisions are at random angles and the galaxies that collide can have different rotational directions.

That fact that observationally spiral galaxies multiple parameters are tightly controlled by some "parameter" and or mechanism was not expected and has no explanation.

http://arxiv.org/abs/0811.1554

Galaxies appear simpler than expected

Galaxies are complex systems the evolution of which apparently results from the interplay of dynamics, star formation, chemical enrichment, and feedback from supernova explosions and supermassive black holes. The hierarchical theory of galaxy formation holds that galaxies are assembled from smaller pieces, through numerous mergers of cold dark matter. The properties of an individual galaxy should be controlled by six independent parameters including mass, angular-momentum, baryon-fraction, age and size, as well as by the accidents of its recent haphazard merger history. Here we report that a sample of galaxies that were first detected through their neutral hydrogen radio-frequency emission, and are thus free of optical selection effects, shows five independent correlations among six independent observables, despite having a wide range of properties. This implies that the structure of these galaxies must be controlled by a single parameter, although we cannot identify this parameter from our dataset. Such a degree of organisation appears to be at odds with hierarchical galaxy formation, a central tenet of the cold dark matter paradigm in cosmology.

If Shanks' finding is correct the CMB data cannot be used to support the existence of Dark Matter. The first peak in the CMB data which is alleges to show dark matter exists changes by 30%. Where previously what was predicted agreed with the measurements by better than 1%. Shanks et al used a distance object to calibrate the CMB data analysis. The authors of the original analysis used Jupiter which gave them the answer they wanted. It should be noted the CMB authors knew the answer they wanted (i.e. What the Dark Matter theoretical first CMB peak should be) before did their analysis.

What we have is an unexplained rotational anomaly of spiral galaxies. As noted above the specific variation of rotational velocity with distance from the center of the spiral galaxy changes linearly while the Dark Matter simulations show it should change at 1/radius of the spiral galaxy which will in addition to creating a different rotational variance with distance from the center of the spiral galaxy will based on simulations create a galaxy bulge that is much larger than observed.

As other authors have noted the finding of massive amounts of gas in clusters removes the need for dark matter to explain cluster motions which has the first indication that "dark matter" was needed by the theory.

The point is Dark Matter does not explain the observations. "Dark Matter" is a place holder for what ever mechanism is causing what is observed. New analysis and data refutes the existence of Dark Matter from multiple logical bases.

 

[Chalnoth]

The problem is that simulations produce what is observed for an elliptical galaxy.

So? Elliptical galaxies are quite a bit simpler.

If Shanks' finding is correct the CMB data cannot be used to support the existence of Dark Matter. The first peak in the CMB data which is alleges to show dark matter exists changes by 30%.

There's no possibility of changing the first peak by 30%. Anyway, it's the ratio between the even and odd peaks that is important, not the amplitude of the first peak.

Where previously what was predicted agreed with the measurements by better than 1%. Shanks et al used a distance object to calibrate the CMB data analysis. The authors of the original analysis used Jupiter which gave them the answer they wanted.

That's nonsense. Jupiter has a vastly smaller angular size than the beam, so its size had very little impact on the beam shape. And by the way, the WMAP team also made use of Mars, Saturn, Uranus, Neptune, and five celestial sources. They also took into account seasonal variation and the angular size of their sources in the calculations. You can read the full paper in detail here:
http://lambda.gsfc.nasa.gov/product...evenyear/calibrators/wmap_7yr_calibrators.pdf

The main point here is that Jupiter is by far the brightest source in the sky at the wavelengths WMAP is looking at. So it would be foolish not to use it to calibrate the instrument. Only using much lower signal-to-noise sources like distant quasars is more likely to lead to an incorrect result.

Then there's also the point that if the WMAP result were off by 30%, ground and balloon-based measurements of the CMB would be completely inconsistent with WMAP. So no, there is no possibility of the WMAP beam shape being off by enough to change the first peak by 30%.

What we have is an unexplained rotational anomaly of spiral galaxies. As noted above the specific variation of rotational velocity with distance from the center of the spiral galaxy changes linearly while the Dark Matter simulations show it should change at 1/radius of the spiral galaxy which will in addition to creating a different rotational variance with distance from the center of the spiral galaxy will based on simulations create a galaxy bulge that is much larger than observed.

Far more likely to be an issue with the simulations than fundamental physics. Spiral galaxies are horribly complex beasts.

As other authors have noted the finding of massive amounts of gas in clusters removes the need for dark matter to explain cluster motions which has the first indication that "dark matter" was needed by the theory.

Uh, what? Look at the Bullet Cluster. The mass is not in the same location as the cluster gas, ergo the cluster gas isn't the explanation.

The point is Dark Matter does not explain the observations. "Dark Matter" is a place holder for what ever mechanism is causing what is observed. New analysis and data refutes the existence of Dark Matter from multiple logical bases.

Sorry, but in every single observation where the systematic errors are well-controlled, dark matter provides an excellent fit to the data. It is only when we start moving into areas where the systematic errors aren't as well-understood (such as within spiral galaxies) that we start to have problems.

 

[Saul]

So? Elliptical galaxies are quite a bit simpler.

Elliptical galaxies are more complicated. Not simpler.

I notice that you have stopped your argument that internal friction of a collapsing gas cloud will make it rotate. That is incorrect.

Observational Disney et al has shown that Spiral/Disk galaxy's parameters are controlled by a single parameter. There is no explanation for that observation.

The mass of the spiral/disk galaxy increases by a factor 7 as compared to the host's galaxies BH from z=3 to z=0. There is not explanation for that observation.

I will respond to your comments on Dark Matter and Shanks' CMB analysis in the CMB thread.

 

[Chalnoth]

Elliptical galaxies are more complicated. Not simpler.

They're simpler in the sense that the physics is simpler.

I notice that you have stopped your argument that internal friction of a collapsing gas cloud will make it rotate. That is incorrect.

It was also never my argument. My argument was that friction causes the gas cloud to collapse. Absent friction, a gas cloud would equilibrate at a rather large size with no apparent rotation (or at least very low rotation). With friction, the gas cloud is allowed to collapse inward, causing an increase in rotational velocity.

 

[Saul]

I support the above comment that friction and a gas's ability to radiate energy enables a gas cloud to collapse. As I noted there is no explanation as to why the massive gas clouds associated with clusters have not collapsed. The clouds in question have had sufficient time to collapse. As the cloud density increases the internal friction of the cloud increases.

Back to the discussion of why are spiral galaxies simple (controlled) and the related question which is how do spiral galaxies avoid becoming elliptical galaxies due to mergers.

The point of this thread is Disney et al's discovery that spiral galaxies are controlled by a single parameter or mechanism changes the problem situation. As Disney et al note it appears only the correct theory/mechanism will explain that observations.

Dark matter was a guess. It cannot explain the spiral and disk galaxy's rotational curve and there is no indication it will explain Disney et al's discovery.

http://arxiv.org/abs/astro-ph/0702585v1

“The Milky Way: An Exceptionally Quiet Galaxy; Implications for the formation of spiral galaxies”, by F. Hammer, M. Puech, L. Chemin, H. Flores, M. Lehnert

Disk galaxies constitute the majority of the galaxy population observed in the local universe. They represent 70% of intermediate mass galaxies (stellar masses ranging from 3× 10^10 to 3 × 10^11 M⊙), which themselves include at least two-third of the present-day stellar mass (e.g., Hammer et al. 2005). Early studies of the Milky Way have led to a general description of the formation of a disk galaxy embedded in a halo (Eggen, Lynden-Bell, & Sandage 1962). Fall & Efstathiou (1980) set out a model of galaxy formation assuming that disks form from gas cooling and condensing in dark halos. Protogalactic disks are assumed to be made of gas containing substantial amount of angular momentum, which condenses into stars to form thin disks (Larson 1976). These disks then evolve only through secular processes.

However, there are several outstanding difficulties with this standard scenario. One such difficulty is the so-called angular momentum problem. That is, simulated galaxies cannot reproduce the large angular momentum observed in nearby spiral galaxies (e.g., Steinmetz & Navarro 1999). Another is the assumed absence of collisions during and after the gas condensation process. Indeed, the hierarchical nature of the ΛCDM cosmology predicts that galaxies have assembled a significant fraction of their masses through collisions with other galaxies. It is likely that such collisions would easily destroy galactic disks (e.g., Toth & Ostriker 1992).

Using arguments based on either dynamical friction (Binney & Tremaine 1987) or simple orbital time-scale (e.g.,Bell et al. 2006), this time scale has been estimated to be about 0.35Gyrs. Combining the pair fraction and characteristic time scale estimates suggests that for a present-day galaxy with a stellar mass larger than 3 × 10^10 solar masses, the chance it has experienced a major merger since z=1 is 50±17%, 75±25% and 70% according to Lotz et al. (2006), Hammer et al. (2005), and Bell et al. (2006), respectively1. Although less certain, integrating the merger rate to higher redshift implies that a typical bright galaxy may have experienced up to four to five major merging events since z=3 (Conselice et al. 2003).

The widely accepted assumption that a major merger would unavoidably lead to an elliptical is perhaps no longer tenable: accounting for the large number of major mergers that have apparently occurred since z=3 would imply that all present day galaxies should be ellipticals. This is obviously not the case. So it is likely that disks either can survive or are “rebuilt” after a major merger, through whatever mechanism as yet perhaps unknown in detail (see, for example, Robertson et al. 2006).

 

[Chalnoth]

I support the above comment that friction and a gas's ability to radiate energy enables a gas cloud to collapse. As I noted there is no explanation as to why the massive gas clouds associated with clusters have not collapsed. The clouds in question have had sufficient time to collapse.

Really? Have you done the calculations?

Dark matter was a guess. It cannot explain the spiral and disk galaxy's rotational curve and there is no indication it will explain Disney et al's discovery.

I think you should have bolded this statement instead:

The widely accepted assumption that a major merger would unavoidably lead to an elliptical is perhaps no longer tenable

 

[Saul]

This paper is interesting on two fronts.

The first is on the existence of dark matter. If they could definitely show star motion in elliptical galaxies indicates a lack of dark matter, they would have disproved the existence of dark matter as its not physically possible to have clouds of dark matter around spiral galaxies and not around elliptical galaxies.

The second point is why are spiral and elliptical galaxies different?

A subsequent paper was published entitled Dark matter lost and found. However that paper did not prove dark matter is associated with elliptical galaxies. That paper alleged that elliptical star motion was greater than observed, which would then enable dark matter to exist around the elliptical galaxy.

The point of submitting this specific paper is the issue of does or does not dark matter exist is not settled.

The second point is the fundamental issue as to what causes the two different galaxy types elliptical and spiral is not known.

http://arxiv.org/abs/astro-ph/0308518v1

A Dearth of Dark Matter in Ordinary Elliptical Galaxies

The kinematics of the outer parts of three intermediate-luminosity elliptical galaxies have been studied using the Planetary Nebula Spectrograph. The galaxies’ velocity dispersion profiles are found to decline with radius; dynamical modeling of the data indicates the presence of little if any dark matter in these galaxies’ halos. This surprising result conflicts with findings in other galaxy types, and poses a challenge to current galaxy formation theories.

Over the past twenty-five years, astronomers have gone from being surprised by the existence of dark matter to the understanding that in fact most of the Universe is dominated by exotic non-luminous material. In the prevailing paradigm, the gravitational influence of “cold dark matter” (CDM) is crucial to the formation of structure, seeding the collapse and aggregation of today’s luminous systems. An inherent consequence of this picture is that galaxies have massive, extended CDM halos. Indeed, such halos are evident around spiral galaxies, where the rotational speeds in their extended cold gas disks do not decrease outside the visible stars—a gravitational signature of dark matter (1). The evidence for dark matter in elliptical galaxies is still circumstantial. Assessments of the total masses of individual elliptical systems have generally been confined to the very brightest ones, where the gravitational potential may be measured using x-ray emission (2) or strong gravitational lensing (3), and to nearby dwarfs, where the kinematics of individual stars offer a probe of the mass distribution (4).

 

[Jonathan Scott]

Bath water forms a vortex because the planet rotates.

The resultant of collapsing gas clouds will not rotate if it did not have initial angular momentum.

http://www.loc.gov/rr/scitech/mysteries/coriolis.html

It's a myth that the rotation of the Earth has anything to do with the bath water vortex.

It's also statistically implausible (as Chalnoth has also said) that the random component of angular momentum would add up to zero, or even anywhere close. That's like throwing a coin thousands of times and having it come out with exactly the same number of heads and tails.

 

[Chalnoth]

As I said before, the best evidence for dark matter comes from studies where the systematic errors are relatively well-understood. The systematic errors are not well-understood for galaxies, and thus a discrepancy that we see there is more likely to do with our model of the galaxies themselves instead of fundamental physics.

 

[Saul]

It's a myth that the rotation of the Earth has anything to do with the bath water vortex.

It's also statistically implausible (as Chalnoth has also said) that the random component of angular momentum would add up to zero, or even anywhere close. That's like throwing a coin thousands of times and having it come out with exactly the same number of heads and tails.

I am not sure I understand the analogue that flipping a coin a million times has on the finding that spiral/disk galaxies are simpler (patterned, controlled) than expected.

The point is random physical events and properties that should affect the spiral galaxy such as new gas in falling, mergers with other galaxies, the initial rotation of the gas cloud, redshift when the galaxy initial formed, the metallicity of gas in the galaxy, and so on, are overridden by some parameter or mechanism.

http://arxiv.org/abs/0811.1554

Galaxies appear simpler than expected

Galaxies are complex systems the evolution of which apparently results from the interplay of dynamics, star formation, chemical enrichment, and feedback from supernova explosions and supermassive black holes. The hierarchical theory of galaxy formation holds that galaxies are assembled from smaller pieces, through numerous mergers of cold dark matter. The properties of an individual galaxy should be controlled by six independent parameters including mass, angular-momentum, baryon-fraction, age and size, as well as by the accidents of its recent haphazard merger history. Here we report that a sample of galaxies that were first detected through their neutral hydrogen radio-frequency emission, and are thus free of optical selection effects, shows five independent correlations among six independent observables, despite having a wide range of properties. This implies that the structure of these galaxies must be controlled by a single parameter, although we cannot identify this parameter from our dataset. Such a degree of organisation appears to be at odds with hierarchical galaxy formation, a central tenet of the cold dark matter paradigm in cosmology.

 

[Saul]

It's a myth that the rotation of the Earth has anything to do with the bath water vortex.

It's also statistically implausible (as Chalnoth has also said) that the random component of angular momentum would add up to zero, or even anywhere close. That's like throwing a coin thousands of times and having it come out with exactly the same number of heads and tails.

Because we were discussing spin, this additional quote from Disney et al's paper seems relevant. Does Disney's statement make sense?

http://arxiv.org/abs/0811.1554

If, as we have argued, galaxies come from at most a six-parameter set, then for gaseous galaxies to appear as a one-parameter set, as observed here, the theory of galaxy formation and evolution must supply five independent constraint equations to constrain the observations. This is such a stringent set of requirements that it is hard to imagine any theory, apart from the correct one, fulfilling them all. For instance, consider heirarchical galaxy formation in the dark matter model, which has been widely discussed in the literature3,4. Even after extensive simplification, it still contains four parameters per galaxy: mass, spin, halo-concentration index and epoch of formation.

Consider spin alone, which is thought to be the result of early tidal torquing. Simulations produce spins, independent of mass, with a log-normal distribution. Higher-spin discs naturally cannot contract as far; thus, to a much greater extent than for low-spin discs, their dynamics is controlled by their dark halos, so it is unexpected to see the nearly constant dynamical-mass/luminosity ratio that we and others14 actually observe. Heirarchical galaxy formation simply does not fit the constraints set by the correlation structure in the Equatorial Survey.