Galaxy motions -> hidden superstructure (DM)

[Loren Booda]

My two cents, from http://www.quantumdream.net :

The "Hubble acceleration," a_H=c²/R_H=cH₀=6 x 10^-8 cm/s², demarcates a critical radial acceleration for galaxies and larger bodies where the influence of so-called dark matter begins. Following the rotation curve for a given galaxy, one notices the departure from conventional luminous matter dynamics at approximately the rotational velocity v with radius r so that a_H=v²/r. This asserts that the radial universal expansion parameters, i. e., the Hubble acceleration, also affect rotational dynamics. The concept of "dark matter" may arise in large part to a quantizing of a_H. If so, this would indicate a characteristic of baryonic matter's inertia to overcome an "ultraviolet catastrophe" (similar to the blackbody's). Consequently, it tends to maintain the acceleration, and likewise the velocity, of galaxies' outlying halos.

The effects of "dark matter" on large-scale structures are predominantly due to compliance with discretized minimal acceleration, given by the ratio between speed of light squared and the cosmological horizon radius.

 

[turbo]

I still believe that the bridge connecting M51 with the other galaxy is a tidal arm. The Toomre brothers demonstrated in 1972 that gravitational interactions can cause these filamentary bridges to occur, so case closed
It's like going to a castle by night in search of phantoms. if you are suggestive to see them, you will see one behind each corner. If you want to see ejections in images that can be explained other way you will see ejections. But I prefer to follow the mainstream, the truth uses to be always with the point of view of the majority

I am so glad that you pointed out the work of the Toomre brothers, and thus "closed the case" on any possible alternate interpretation of the data. Is it possible that other astronomers may contribute anything, or have the Toomre brothers solved everything? "Case closed", indeed!

 

[Chronos]

Your are kidding about the "rigorous study, right?"
I hope so. That paper is lame in so many ways.

Elaborate. Which parts are lame.

The more complex the "explanation" for a particular observation, the more certain you can be that it is absolutely wrong.

I would argue the more diffuse and inspecific the argument becomes, the more likely it is false.

In this case, the obvious distortions of M51 are "explained away" as if its companion has made a concerted but very complex multi-pass attack on it. There is a relatively simple explanation for M51's appearance, and it does not involve a "Kung Fu" battle between the host and the companion. The companion was ejected, and it distorted the arms of the host in the process.

Please reference a paper that supports that position.

You may not like this, but Arp's Atlas of Interacting Galaxies will give you enough examples to refute to keep you busy for the rest of your life (assuming you will not simply nay-say every one). If you have not browsed that work, you should spend a few hours on it:

I am fairly familiar with the Arp Atlas of galactic freaks.

As I have said, Arp has been studying galaxy morphology for decades longer than most cosmologists have been alive.

So have creationists.

Look at the examples, and try to think how these galaxies connected by filaments or obviously skewed by tidal distortion could possibly exhibit these abnormalities in "anticipation" of future interaction. The lame half-witted "capture" model dies here, OK?

Do you have an example that resists conventional explanations? Apparently not. All I asked for was a single study that suggests expulsion cosmology has any basis in fact.

Now, is it even possible in your estimation that any of these interactions are the result of an ejection phenomenon, or must every single one of them be a result of a collision? You don't have to reply right away, and I'm not going to demand math. Please think before answering, though, and go with your gut.

What I see is a lack of evidence supporting any of the Arp assertions. No papers, no objective evidence, no substantial objections to the preponderance of evidence against the Arp assertions. Frankly all I see is a bunch of 'hand waving', as Nereid would say.

 

[turbo]

All I asked for was a single study that suggests expulsion cosmology has any basis in fact.

I guess these poor misguided folks have not had the benefit of your wisdom. Perhaps you should contact them.

http://online.itp.ucsb.edu/online/bhole_c99/mushotzky/inflow.html

 

[turbo]

What I see is a lack of evidence supporting any of the Arp assertions. No papers, no objective evidence, no substantial objections to the preponderance of evidence against the Arp assertions. Frankly all I see is a bunch of 'hand waving', as Nereid would say.

We had a little discussion of the problems with the Heirarchical Model some time back - perhaps you missed it.

https://www.physicsforums.com/showthread.php?t=26644&page=4

There are problems with that model, as demonstrated by the very energetic and highly organized structures (galaxies and quasars) that we see in the infancy of the (presumed) 13.7Gy BB universe. In light of this situation, it is logical that fission/ejection processes are important in the evolution of galaxies.

If you can come up with any logical model that forbids mass ejection by galaxies, I would love to see it. Then, I will happily watch you reconcile it with the Heirarchical Model (see above).

 

[Garth]

My two cents, from http://www.quantumdream.net :

The "Hubble acceleration," a_H=c²/R_H=cH₀=6 x 10^-8 cm/s², demarcates a critical radial acceleration for galaxies and larger bodies where the influence of so-called dark matter begins.

Just to give my two pennyworth...

This acceleration is also that of the Pioneer anomaly (almost).

SCC explains that anomaly as a clock drift between ephemeris time (that kept by the spacecraft 's orbit) and atomic time ( that kept by the apparatus measuring the doppler shift)

Now how does that apply to galactic rotations?...

Garth

 

[turbo]

All I asked for was a single study that suggests expulsion cosmology has any basis in fact.What I see is a lack of evidence supporting any of the Arp assertions. No papers, no objective evidence, no substantial objections to the preponderance of evidence against the Arp assertions. Frankly all I see is a bunch of 'hand waving', as Nereid would say.

You haven't responded to my previous posts - have you done any kind of searching to see what kinds of models might support Arp's model? Let me steer you toward some interesting work (yes, there are many papers involved, if that will make you more comfortable). Google on "radiation recoil" AND "black hole". After that, you can substitute "three-body slingshot" and "black hole" (or something similar) because there are other mechanisms for black-hole ejection. You will see that there are quite a few people modeling mass ejection from galactic cores, specifically massive black holes in these cases.

Zoltan Haiman uses the radiation recoil model to place constraints on the growth rates of supermassive black holes. Of course the extreme redshifts of the quasars he cites cause problems, because if the redshifts are truly indicative of cosmological distance, there appears to have been insufficient time for the quasars' black holes to form.

http://citebase.eprints.org/cgi-bin/citations?id=oai%3AarXiv%2Eorg%3Aastro%2Dph%2F0404196

What does black hole ejection have to do with Arp? It provides a mechanism for quasars to be emitted from galaxies. It is fairly non-controversial that a quasar's energy is derived from matter falling into a black hole. If quasars are relatively nearby objects, ejected from host galaxies, their apparent excess luminosities are no longer a problem. The question is "what causes the excess red shift"?

 

[Chronos]

I fail to see how radiation recoil is relevant to the issue we were discussing. Why would an 'expelled' black hole suddenly become a quasar while the bully galactic black hole that evicted it does not?

Dear Chronos, if you can rigorously examine and demonstrate that any of these interactions ARE collision or capture events, I wil be happy to review your work. You can start with the M51 system.

Other researchers have already done that... at risk of sounding repetitive

The appearance of M51 is nicely explained by this paper
http://cc.oulu.fi/~hsalo/M51_I_SL_2000.pdf.
An ordinary collision model accounts for observation. The prevalence of the young star forming regions is due to gas cloud collisions. This paper confirms prior studies [as referenced in the paper] where the same conclusions were reached. The case against ejection appears to be pretty solid.

 

[Loren Booda]

Garth,

This acceleration is also that of the Pioneer anomaly (almost).

That Pioneer anomaly, unless it describes a universal constant (not restricted to the Pioneer spacecraft and our solar system), probably signifies a numerologic coincidence with the Hubble acceleration. Can you show it to hold consistently for another spaceship amongst other regions of the galaxy?

 

[Garth]

Garth, That Pioneer anomaly, unless it describes a universal constant (not restricted to the Pioneer spacecraft and our solar system), probably signifies a numerologic coincidence with the Hubble acceleration. Can you show it to hold consistently for another spaceship amongst other regions of the galaxy?

You'll have to wait for "the other regions of the galaxy"!
I quote from some relevant papers:

Nieto et al.: http://arxiv.org/abs/gr-qc/0308017
"First published in 1998, results from an almost twenty years study of radiometric data from Pioneer 10/11, Galileo and Ulysses spacecraft have been continuously reported by Anderson et al. They indicate an apparent anomalous, constant, acceleration acting on the spacecraft with magnitude aP = (8.74 ± 1.33) x 10^−8 cm/s/s, directed towards the Sun, to within the accuracy of the Pioneers’ antennas."
and Mbelek et al. : http://arxiv.org/abs/gr-qc/0310088
"Attempts to verify the anomaly using other spacecraft proved disappointing. This is because the Voyager, Galileo, Ulysses, and Cassini spacecraft navigation data all have their own individual difficulties for use in an independent test of the anomaly."

So make of that what you will - the anomaly seems not to be explained by mundane causes such as gas leakage or anisotropic radiation reaction, I do not believe it is a coincidence that it is almost equal to the Hubble acceleration. But then I am biased!

Garth

 

[turbo]

I fail to see how radiation recoil is relevant to the issue we were discussing. Why would an 'expelled' black hole suddenly become a quasar while the bully galactic black hole that evicted it does not?

You didn't do the Google search and scan the papers, did you? The entire merged black hole is kicked out of the glactic core, radiating linear momentum. When it sweeps up matter and starts "feeding", we see a quasar.

It is commonly thought that quasars are black holes that are "feeding". There are indications that a binary black hole system will quickly clear the stars out of a surrounding volume of space by sweeping up some them, and perturbing a lot of them out of the area. This greatly reduces the infall rate for those BHs. The black hole(s) presumed to be at the center of the MW are presently not feeding, for instance. When the binary merges, the perturbative effects caused by the binary system go away, and the black hole can resume growing by accretion (and take on the appearance of a quasar). If the black hole did not have to shed enough linear momentum (radiation recoil), it may only be displaced in its galactic core and eventually settle back toward the center (wreaking havok in the meantime). If it does get ejected by the kick, it can sweep up matter on its way out and start feeding by accretion. Please give the papers at least a cursory scan.

 

[Nereid]

My two cents, from http://www.quantumdream.net :

The "Hubble acceleration," a_H=c²/R_H=cH₀=6 x 10^-8 cm/s², demarcates a critical radial acceleration for galaxies and larger bodies where the influence of so-called dark matter begins. Following the rotation curve for a given galaxy, one notices the departure from conventional luminous matter dynamics at approximately the rotational velocity v with radius r so that a_H=v²/r. This asserts that the radial universal expansion parameters, i. e., the Hubble acceleration, also affect rotational dynamics. The concept of "dark matter" may arise in large part to a quantizing of a_H. If so, this would indicate a characteristic of baryonic matter's inertia to overcome an "ultraviolet catastrophe" (similar to the blackbody's). Consequently, it tends to maintain the acceleration, and likewise the velocity, of galaxies' outlying halos.

The effects of "dark matter" on large-scale structures are predominantly due to compliance with discretized minimal acceleration, given by the ratio between speed of light squared and the cosmological horizon radius.

The link doesn't seem to be working Loren.

This idea should be extremely easy to test against a mass of existing data - rotation curves for galaxies, 3D motion of Milky Way halo objects (e.g. globular clusters) - have you looked at the data?

 

[Nereid]

I am so glad that you pointed out the work of the Toomre brothers, and thus "closed the case" on any possible alternate interpretation of the data. Is it possible that other astronomers may contribute anything, or have the Toomre brothers solved everything? "Case closed", indeed!

What the Toomre brother did was show that many of the filaments, distorted disks, and other strange shapes in images of galaxies such as in Arp's collection (and Zwicky's before that) *could* be produced by gravitational forces during galaxy collisions (in the broadest sense). IIRC, at the time this was rather a surprise. Around the same time, King started doing his thing on radial luminosity profiles, and showed that for many (elliptical) galaxies the profiles were best accounted for by 'tidal interactions'. This work, which owed much to de Vaucouleurs, subsequently lead to the 'generalised Navarro, Frenk and White' (or NFW) profiles. Further advances in computing power lead to much more detailed galaxy collision modeling.

AFAIK, there isn't any serious disagreement with the ability of the models to produce all observed features in images and spectra of interacting galaxies. Further, the observed radial profiles of galaxies not apparently interacting are also well understood, and consistent with a model that includes DM (one of my favourite examples of interaction is not a galaxy at all, but the globular http://www.aas.org/publications/baas/v34n2/aas200/475.htm ).

Finally, for the avoidance of doubt, galaxy evolution continues to be a field of vigourous research, with new results coming out in respect of things such as the cause and evolution of bars, the role of magnetic fields, the extent to which dwarf galaxies are evolved (the recent Subaru results suggest at least one local one has undergone quite some), and much more.

 

[Nereid]

We had a little discussion of the problems with the Heirarchical Model some time back - perhaps you missed it.

https://www.physicsforums.com/showthread.php?t=26644&page=4

There are problems with that model, as demonstrated by the very energetic and highly organized structures (galaxies and quasars) that we see in the infancy of the (presumed) 13.7Gy BB universe. In light of this situation, it is logical that fission/ejection processes are important in the evolution of galaxies.

If you can come up with any logical model that forbids mass ejection by galaxies, I would love to see it. Then, I will happily watch you reconcile it with the Heirarchical Model (see above).

IMHO, this is really a topic we should have some threads on! As readers probably know, it relates to cosmological models and large scale structure, and there's been lots of breathless PRs in the past few years, from various researchers, announcing its death.

 

[Nereid]

You'll have to wait for "the other regions of the galaxy"!
I quote from some relevant papers:

Nieto et al.: http://arxiv.org/abs/gr-qc/0308017
"First published in 1998, results from an almost twenty years study of radiometric data from Pioneer 10/11, Galileo and Ulysses spacecraft have been continuously reported by Anderson et al. They indicate an apparent anomalous, constant, acceleration acting on the spacecraft with magnitude aP = (8.74 ± 1.33) x 10^−8 cm/s/s, directed towards the Sun, to within the accuracy of the Pioneers’ antennas."
and Mbelek et al. : http://arxiv.org/abs/gr-qc/0310088
"Attempts to verify the anomaly using other spacecraft proved disappointing. This is because the Voyager, Galileo, Ulysses, and Cassini spacecraft navigation data all have their own individual difficulties for use in an independent test of the anomaly."

So make of that what you will - the anomaly seems not to be explained by mundane causes such as gas leakage or anisotropic radiation reaction, I do not believe it is a coincidence that it is almost equal to the Hubble acceleration. But then I am biased!

Garth

The good news is that LISA will be able to detect any such acceleration (and much else) ; the bad news is that it's not due for launch until 2012

Anyone know of anything planned that will help nail down the anomaly before then?

 

[Nereid]

Dear Nereid, the letter is not an "accusation" aimed at people whose research is aimed at bolstering the standard cosmologies. It is a statement of principal that funding should not be denied nor professional resources withheld from people whose lines of inquiry diverge from the "concordance models", lest potentially valuable insights go unexplored.

I was not aware that is was belligerent, just speaking its mind. Its key recommendation: "To redress this, we urge those agencies that fund work in cosmology to set aside a significant fraction of their funding for investigations into alternative theories and observational contradictions of the big bang." is motivated by a desire for good scientific practice - but also, I must admit, probably a little resentment that such funding hasn't already been forthcoming.

I’ve been puzzling over this part.

First, in terms of new space-based science, can any in the ‘alternatives’ camp honestly say that the current missions (e.g. WMAP, Spitzer, Hubble, Integral) or planned missions (e.g. JWST, LISA, GLAST) were designed in such a way as to preclude tests of their favourite alternative ideas? If so, what and how? I’m not talking about funds for the analyses of data, or how observations are scheduled, just the mission designs.

Second, can any in the ‘alternatives’ camp honestly say that the current or planned missions deny access to the data from the missions, at an appropriately early stage of the pipeline, so as to preclude tests of their favourite alternative ideas? If so, what and how?

Third, other than funds for tea and biscuits (and computer time), what resources do those in the ‘alternatives’ camp lack, wrt pursuing their research?

Fourth, if those in the ‘alternatives’ camp had the budget for a dream space-based mission or three, how would they differ from current and planned missions?

Fifth, what ground-based observational program (or CERN/SLAC etc one) would those in the ‘alternatives’ camp wish to pursue? I’m only interested in ones that would be significantly different from those which the likes of Gemini, Subaru, Keck, VLT, etc are already devoting much time to. I’m also interested in what significantly new or different instruments for these facilities these folk would have liked to have had developed (e.g. what would they have built instead of Subaru’s Suprime-Cam?)

Sixth, how many high quality proposals have those in the ‘alternatives’ camp submitted in response to the open calls for proposals, from Integral, Cosmic Visions, Newton-XMM, Hubble, etc? Ditto, wrt proposals for use of the Directors’ discretionary time on these missions?

 

[Garth]

First, in terms of new space-based science, can any in the ‘alternatives’ camp honestly say that the current missions (e.g. WMAP, Spitzer, Hubble, Integral) or planned missions (e.g. JWST, LISA, GLAST) were designed in such a way as to preclude tests of their favourite alternative ideas?

They were not - indeed GPB is ideal for testing such alternatives - SCC and Moffat's non-symmetric gravitational theory (NGT) [see "Modified Gravitational Theory and the Gravity Probe-B Gyroscope Experiment" http://arxiv.org/abs/gr-qc/0405091] .

The question how would a non-GR outcome of the experiment be interpreted should it occur?

Fourth, if those in the ‘alternatives’ camp had the budget for a dream space-based mission or three, how would they differ from current and planned missions?

1. The space-borne interferometer to test whether photons and particles fall 'at the same rate': "Self Creation Cosmology An Alternative Gravitational Theory" http://arXiv:gr-qc/0405094 Section 7.1 pg 17.
2. The deep-space Casimir force experiment to test whether there is a cut off of the Casimir force at great distances from the Sun. (ibid)

Fifth, what ground-based observational program (or CERN/SLAC etc one) would those in the ‘alternatives’ camp wish to pursue?

The truncated LIGO type interferometer, to test the same question as 1 above.

I can partly understand Nereid's puzzlement over the statement. However I would like to point out that, apart from a motley collection of such as myself who might be called 'crackpots' by some, there are a number of respected figures who have signed the statement such as Bondi, Gold and Narlikar. But why have they? Unless it is that the standard-model landscape, and the confidence it inspires, should appear different on the other side of the fence.

Who was it that said, “Cosmologists are often in error but never in doubt”?

- Garth

 

[Ian]

You can see only visible light! not all frequencies are visible to our eyes,
dark matter is the same as ordinary matter, we cannot see it or touch it because it is bigger and on another scale.

 

[Garth]

You can see only visible light! not all frequencies are visible to our eyes,
dark matter is the same as ordinary matter, we cannot see it or touch it because it is bigger and on another scale.

Understood Ian, but the standard model says DM cannot be the same as ordinary matter, i.e. baryonic, as there is too much of it. Standard GR BB nucleo-synthesis allows only a maximum of 4% critical density as ordinary matter (and that is pushing it) whereas galactic dynamics and lensing observations require about 20%, or more. So what is it?

However if the GR R(t) ~ t^(1/2) then t^(2/3) in the radiation and matter dominated epochs respectively is replaced by R(t) ~ t all the way through in the freely coasting model then nucleo-synthesis allows 20% baryonic density + neutrino etc contributions, so the problem is solved. And you will be right; DM is ordinary matter!

- Garth

 

[Mike2]

Understood Ian, but the standard model says DM cannot be the same as ordinary matter, i.e. baryonic, as there is too much of it. Standard GR BB nucleo-synthesis allows only a maximum of 4% critical density as ordinary matter (and that is pushing it) whereas galactic dynamics and lensing observations require about 20%, or more. So what is it?

I've not seen the data. Are the galactic rotation curves and the lensing effects just as strong for Andromeda as for very distant galaxies? Thanks.

 

[Nereid]

They were not - indeed GPB is ideal for testing such alternatives - SCC and Moffat's non-symmetric gravitational theory (NGT) [see "Modified Gravitational Theory and the Gravity Probe-B Gyroscope Experiment" http://arxiv.org/abs/gr-qc/0405091] .

Good to hear.

The question how would a non-GR outcome of the experiment be interpreted should it occur?

Indeed! It should be an exciting time, should it not?

1. The space-borne interferometer to test whether photons and particles fall 'at the same rate': "Self Creation Cosmology An Alternative Gravitational Theory" http://arXiv:gr-qc/0405094 Section 7.1 pg 17.

I'd be interested to hear whether you think the proposals in Cosmic Visions (or the NASA equivalent) will cover this.

2. The deep-space Casimir force experiment to test whether there is a cut off of the Casimir force at great distances from the Sun. (ibid)

AFAIK, there are no deep space experiments planned, by anyone, for any purpose (unless you count the Pluto-Kuiper Express, which is all but dead, no?)

The truncated LIGO type interferometer, to test the same question as 1 above.

To what extent would LISA be able to serve as an alternative? What about the resonant mass gravity wave detectors?

I can partly understand Nereid's puzzlement over the statement. However I would like to point out that, apart from a motley collection of such as myself who might be called 'crackpots' by some, there are a number of respected figures who have signed the statement such as Bondi, Gold and Narlikar. But why have they?

That's what I'm trying to understand! If none of the missions preclude tests of any alternatives, and if there are but a small number of dedicated missions that the iconclasts would dream of, where's the beef (other than pocket money for tea and biccies)?

 

[Chronos]

Speaking of large scale structure and the standard model, this is interesting
http://www.arxiv.org/abs/astro-ph/0404111

 

[Garth]

On possible non-GR outcome of GPB experiment:

It should be an exciting time, should it not?

If such an outcome should occur do you think they will devise another epicycle?

I'd be interested to hear whether you think the proposals in Cosmic Visions (or the NASA equivalent) will cover this.

AFAIK it does not - however not having broadband I haven't been able to download all those files on your link - yet!

AFAIK, there are no deep space experiments planned, by anyone, for any purpose (unless you count the Pluto-Kuiper Express, which is all but dead, no?).

It has been suggested that a Pioneer Anomaly test be put onboard a low-mass, low-thrust mission to Pluto, the Pluto orbiter Probe or POP. A study of such a mission has been undertaken recently in ESA’s Advanced Concepts Team and detailed results of the system design and trajectory design have been presented in T. Bondo et al, “Preliminary Design of an Advanced Mission to Pluto”. Proceeding of the 24th ISTS, Miyazaki, Japan, June 2004. http://www.esa.int/gsp/ACT/doc/ACT-RPR-4200-ISTS2004.pdf . I have no idea as to whether or when it would get off the ground.

To what extent would LISA be able to serve as an alternative? What about the resonant mass gravity wave detectors?

The experiment compares the gravitational attraction of a horizontal light beam against that of a solid apparatus. I do not think LISA will comply, the gravitational bending of light being equal in GR and SCC.
[Such deviation being of two components, one due to the 'free fall' of the photon the other due to the curvature of space - in GR these two contribute 1/2 + 1/2 respectively to the total deviation; in SCC they contribute 3/4 + 1/4 respectively of the same total deviation 1.75".]
- Garth

 

[Nereid]

On possible non-GR outcome of GPB experiment:

Indeed! It should be an exciting time, should it not?

The question how would a non-GR outcome of the experiment be interpreted should it occur?

If such an outcome should occur do you think they will devise another epicycle?

It's pure physics, so lots of $$ will be found to do a bigger and better GPB; ten thousand new 'GR-killer' theories will flow from the word processors of theorists; ten creative ideas to test the new theories will be published, involving little more than what can be found in a leading university lab; three hundred extensive data-mining projects will be commenced, using BOINC (the new grid computing platform on which Seti@Home now runs); ... and key insight for 'the answer' will come from the mind of a bright young PhD student in China (or India).

 

[malthis]

DM as higher vibrations?

Good discussion here.
I used to deride Dark matter as a makeshift idea to plug the emerging holes in GR, or Newtonian at least. I guess what turned me around is string theory. For once Ican see how DM could exist.

I don't think dark matter is one long brane covering the universe, though that is possible. But perhaps it has to do with the frequency of the wave nature of particles. For example, photons are considered a string just as baryons are, only at a higher vibration. Light happens to be at the upper vibratory limit of what our expanded dimensions can swallow. But does that mean there's no strings that vibrate faster than light? If there were, wouldn't we not see them at all, nor be able to detect them? Would that be, 'dark matter'?

It's something I've thought about and perhaps Tachyons(sp?) are an offshoot of that dea, I don't know much about them though. Anyone like to comment?

 

[Garth]

I've not seen the data. Are the galactic rotation curves and the lensing effects just as strong for Andromeda as for very distant galaxies? Thanks.

Lensing effects do not really apply to Andromeda, although searches are made for 'local' (our galactic halo) micro-lensing events that might be caused by mini black holes or Jupiters. [See today's 'Some Consequences of the Baryonic Dark Matter Population' Rudolph E. Schild http://arXiv:astro-ph/0409549 for distant such objects]

However galactic rotation curves certainly do apply not only to Andromeda but also for the Milky Way itself.

Each galaxy seems to have a massive invisible halo and each galaxy cluster seems to have a massive intergalactic medium, also invisible. Visible matter ~ 4%, Dark Matter ~ 23% of total critical density.

Garth