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Fraser
2007-May-15, 06:15 PM
Astronomers using the Hubble Space Telescope have turned up a ghostly ring of dark matter, surrounding the aftermath of a collision between two galaxy clusters. ...

Read the full blog entry (http://www.universetoday.com/2007/05/15/ring-of-dark-matter-discovered-around-a-galaxy-cluster/)

iantresman
2007-May-16, 10:31 AM
Are there any examples of regular matter forming rings in the same manner?

RussT
2007-May-16, 10:37 AM
How did they get DM to 'shine' BLUE?

Hamlet
2007-May-16, 01:19 PM
How did they get DM to 'shine' BLUE?

It's a composite image. The "blue haze" is a visual representation of the dark matter distribution in the cluster as determined by the researchers. The dark matter map was then superimposed over the Hubble image.

cbacba
2007-May-16, 03:35 PM
what i'd like to know is just how one models mysterious exotic dm when one doesn't know anything about it.

Launch window
2007-May-16, 03:42 PM
Are there any examples of regular matter forming rings in the same manner?

Visual examples I can think of are the Cartwheel Galaxy, NGC 2685, AM 0644-741, NGC4650A, NGC 1097 and Hoag's Ring Galaxy

iantresman
2007-May-16, 04:28 PM
Visual examples I can think of are the Cartwheel Galaxy, NGC 2685, AM 0644-741, NGC4650A, NGC 1097 and Hoag's Ring Galaxy

Here we go, the Cartwheel galaxy (http://apod.nasa.gov/apod/ap010612.html), and similar explanation.

But how do two galaxies get on a collision course in an expanding universe?

Argos
2007-May-16, 04:31 PM
How did they get DM to 'shine' BLUE?
[
It's a composite image. The "blue haze" is a visual representation of the dark matter distribution in the cluster as determined by the researchers. The dark matter map was then superimposed over the Hubble image.

Still, a more detailed description of the technique would be appreciated.

upriver
2007-May-16, 08:15 PM
But how do two galaxies get on a collision course in an expanding universe?


Question of the year!!!!

Notice if its not a perfectly described galaxy its going to, or is in the process of, or has collided.

Everything is gloom and destruction instead of growth and life.

Which is the current mindset of society.

Blob
2007-May-16, 10:00 PM
But how do two galaxies get on a collision course in an expanding universe?

Hum,
are you suggesting that, say, the shoemaker levy comet could not collide with Jupiter, if the universe was expanding?

SPOILER: The answer is simply that the force of gravity is stronger than the force of expansion for the two colliding galaxies in question , (and Jupiter and the comet)....

RussT
2007-May-17, 01:25 AM
http://news.aol.com/topnews/articles/_a/space-hubble-dark-matter-ring/20070515145009990001?cid=2359

Hubble Reveals Ghostly Ring of Dark Matter.

And here is an even worse misrepresentation and really reveals why when we use popularizations taken from these kind of headlines, mainstreamers get so upset.

Hubble found no such thing!!! Hubble CANNOT take pictures of DM!!!

BUT, this does reveal the Gross and egregious misrepresentation that ANY 'Picture' (Visual image) trying to represent what DM is actually doing, really is.



what i'd like to know is just how one models mysterious exotic dm when one doesn't know anything about it.

And this is the biggest question (Not galaxy collision!), and it is the question of the decade (or longer) not just the year.

This is a "Cluster Collision" not a galaxy collision! So all 'those' questions above are moot!

So the question 'could be'...how do clusters collide "IF" all the Voids in-between them, are expanding? AND, expanding faster and faster the farther away they are, and this one is apparently 5 Billion Lys away.

BUT, back to the "Visual Blue Light" that is 'supposed' to depict what shape (and therefore, it's 'supposed' mass and speed) DM takes in the presence of Baryonic Matter.

http://www.bautforum.com/showthread.php?t=58575

Here is the abstract from this paper in the Astronomy section.

So, as Argos suggested above to Hamlet, yes, the devil is in the details!!!



The "blue haze" is a visual representation of the dark matter distribution in the cluster as determined by the researchers

SO, this is all about the "ASSUMPTIONS" they are making in their CDM Lambda Model!!!

So, all of these DM explanations (Including the "Spherical Halos" of DM in galaxies!!!)are based on "Computer Generated" simulations based on N-Body numerical simulations, and THEN they generate a Picture based on these N-body sims and 'super-impose' it onto the Hubble pic of this cluster, and Violla---a "Blue Visual" of their version of what the Exotic Matter is doing.

That is....That the DM is 'slow' and has a 'mass limit'! AND, the reason they 'made up' this whole version of what they 'think' DM is doing, is because the "Hot" DM models wouldn't allow the "Large Structure" that "Fits" the FLRW model!!!

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



In the hot dark matter paradigm, popular in the early eighties, structure does not form hierarchically (bottom-up), but rather forms by fragmentation (top-down), with the largest superclusters forming first in flat pancake-like sheets and subsequently fragmenting into smaller pieces like our galaxy the Milky Way. The predictions of hot dark matter strongly disagree with observations of large-scale structure, whereas the cold dark matter paradigm is in general agreement with the observations.

When they say "Observation" here, they are refering to FLRW 'observation'!

Kwalish Kid
2007-May-17, 05:53 AM
http://news.aol.com/topnews/articles/_a/space-hubble-dark-matter-ring/20070515145009990001?cid=2359

Hubble Reveals Ghostly Ring of Dark Matter.

And here is an even worse misrepresentation and really reveals why when we use popularizations taken from these kind of headlines, mainstreamers get so upset.

Hubble found no such thing!!! Hubble CANNOT take pictures of DM!!!

BUT, this does reveal the Gross and egregious misrepresentation that ANY 'Picture' (Visual image) trying to represent what DM is actually doing, really is.
Your post reveals the gross and egregious misrepresentation of science that can happen when people start mucking about without actually learning the science. And yes, that includes the math.

Hubble is a tool used to produce the detailed measurements required to put together the obervation of the matter.

SO, this is all about the "ASSUMPTIONS" they are making in their CDM Lambda Model!!!
It seems pretty clear that these observations are independent of any particular cosmological model, except for the general assumption that the universe is homogeous enough around the site of the collision to allow for the GR analogue to the hollow sphere theorem of Newton's mechanics to apply.

RussT
2007-May-17, 07:48 AM
It seems pretty clear that these observations

Uh, what 'observations' would those be?

wdavidb
2007-May-17, 09:46 AM
Hum,
are you suggesting that, say, the shoemaker levy comet could not collide with Jupiter, if the universe was expanding?

SPOILER: The answer is simply that the force of gravity is stronger than the force of expansion for the two colliding galaxies in question , (and Jupiter and the comet)....

I have a problem with the idea that gravity is a force, as it would seem that gravity itself is not a force at all.

Concluding the force of gravity is stronger than the force of expansion gives you a very slanted perspective of what is going on out there.

Blob
2007-May-17, 10:58 AM
@wdavidb
Hum,
yes, tnx for pointing it out.
It was a badly worded, hasty reply, on my part, to a seemingly trivial question.


<on topic>

Related Dark matter topic:

Bullet cluster 1E0657-56

http://www.bautforum.com/showthread.php?t=45700&highlight=0657-56

</on topic>

GOURDHEAD
2007-May-17, 01:14 PM
From the linked article:
So how did this ring form? Simulations have shown that when galaxy clusters collide, the dark matter falls into the centre of the combined cluster, and then sloshes back out. As it heads back out, mutual gravity slows it back down, and the dark matter piles up into a ring. I got lost somewhere in the wide margin of what was actually observed and what was speculated. The precision of the term "sloshed" and the physics behind it is suspect.

Has anyone been able to depict the gravity wells of each galaxy in each cluster embedded within their respective clusters and the embedding of the gravity wells of each cluster within the gravity well of the system consisting of all the clusters? Could the space dragging associated with each of these objects cause the accumulation of potential energy stored in the deformation of space which, as it is released (converted to kinetic energy of the motion of the objects) accounts for the observations that have been heretofore attributed to dark matter? By extrapolation, could the expansion, including the inflation period and the current acceleration of expansion, of the universe be yet another manifestation of the unwinding of space dragging associated with "near initial" conditions extant at T+10^-43 seconds after the big bang? That must have been some gravity well at BB + 10^-43 seconds.

antoniseb
2007-May-17, 01:31 PM
From the linked article: I got lost somewhere in the wide margin of what was actually observed and what was speculated. The precision of the term "sloshed" and the physics behind it is suspect.

You have (I think) correctly pointed out that there is some hand-waving in this explanation. The fact is that this concentration of CDM was observed by the weak lensing technique, and that a group ran simulations, and found one that seemed to explain it. The dark matter is there. The collision is one explanation that works, and no others have been found yet, but that doesn't rule out others.

Kwalish Kid
2007-May-17, 01:48 PM
How did they get DM to 'shine' BLUE?
The blue glow is probably gas. The observations of the effects of dark matter is the gravitational lensing of distant objects. Even in the picture, one cannot see any dark matter through cursory visual inspection. One has to sit down and do the math about the position and shape of background sources.

iantresman
2007-May-17, 02:19 PM
The blue glow is probably gas. The observations of the effects of dark matter is the gravitational lensing of distant objects. Even in the picture, one cannot see any dark matter through cursory visual inspection. One has to sit down and do the math about the position and shape of background sources.

Surely the blue glow is a plasma? Am I right to say that gases don't glow?

Blob
2007-May-17, 03:55 PM
Hum,
like something straight out of Douglas Adams' Hitchhiker's Guide to the Galaxy - deciding what colour the ring should be may be simple in comparison to finding out what it is made of.


BTW, i vote we change it to barbie pink

Kwalish Kid
2007-May-17, 04:08 PM
Surely the blue glow is a plasma? Am I right to say that gases don't glow?
Everything (except dark matter ;) ) glows.

antoniseb
2007-May-17, 04:37 PM
The blue glow is probably gas.

You are joking, right? The blue is not a glow, or anything picked up optically. It is the representation of where the dark matter must be as computed by the weak lensing studies.

Jerry
2007-May-17, 05:16 PM
Surely the blue glow is a plasma? Am I right to say that gases don't glow?
As I understand the model, the blue glow is a representation of dark matter derived from the distortions obvious in the clusters underneath - there is no spectral signature other than apparent distortions.

In a cluster environment like this, there is certainly a possibility that baryonic matter - either as plasma, or as a cold gas - is found in the greater cluster environment. In fact, if we are viewing the cluster through an extensive spherical gas cloud that is associated with the cluster, the distortions should appear greatest as rings aligned with our line-of-sight, just as we see distortions in the limbs of planets with transparent atmospheres. The alignment is a red flag, not a green one.

I see this, and the bullet galaxies, as curious phenomenon that deserve careful study. However, the conclusion that either of these events provides strong supportive evidence of dark matter is like finding a pile of horse dung and turning cartwheels because the circus must be in town. We do not know the galactic history of either event with enough certainty to label these inferences as any more than speculative - at least until ordinary baryonic matter can be eliminated. Sometimes a horse is just a horse. Another obvious question is: Could baryonic matter produce greater gravitational lensing of light than expected?

Kwalish Kid
2007-May-17, 05:17 PM
I was of the opinion that the picture was not actually a representation of the distribution, but merely a visual representation of the area.

Looking at the press release about the image, http://hubblesite.org/newscenter/archive/releases/2007/17/image/a/ , it does appear that they have enhanced the image to give an indication of the presence of the ring, but I can't tell whether or not they mean the blue area to indicate the ring or the void to indicate the ring.

Blob
2007-May-17, 05:39 PM
Hum,
there is another thread that has links to the papers...

http://www.bautforum.com/showthread.php?t=58575

dhd40
2007-May-17, 06:03 PM
http://news.aol.com/topnews/articles/_a/space-hubble-dark-matter-ring/20070515145009990001?cid=2359

(snip) Hubble found no such thing!!! Hubble CANNOT take pictures of DM!!!
Absolutely true!
(SNIP)

So, all of these DM explanations (Including the "Spherical Halos" of DM in galaxies!!!)are based on "Computer Generated" simulations based on N-Body numerical simulations, and THEN they generate a Picture based on these N-body sims and 'super-impose' it onto the Hubble pic of this cluster, and Violla---a "Blue Visual" of their version of what the Exotic Matter is doing.

Et voilā, thatīs the explanation! Donīt understand, how people could misunderstand the message.
(SNIP)

dhd40
2007-May-17, 06:09 PM
Hum,
like something straight out of Douglas Adams' Hitchhiker's Guide to the Galaxy - deciding what colour the ring should be may be simple in comparison to finding out what it is made of.


BTW, i vote we change it to barbie pink

No, no! Itīs definitely Paris Hilton rouge

iantresman
2007-May-17, 06:41 PM
Everything (except dark matter ;) ) glows.

Surely not in the visible part of the spectrum? So doesn't only plasma glow?

cbacba
2007-May-18, 08:22 PM
From the linked article: I got lost somewhere in the wide margin of what was actually observed and what was speculated. The precision of the term "sloshed" and the physics behind it is suspect.

Has anyone been able to depict the gravity wells of each galaxy in each cluster embedded within their respective clusters and the embedding of the gravity wells of each cluster within the gravity well of the system consisting of all the clusters? Could the space dragging associated with each of these objects cause the accumulation of potential energy stored in the deformation of space which, as it is released (converted to kinetic energy of the motion of the objects) accounts for the observations that have been heretofore attributed to dark matter? By extrapolation, could the expansion, including the inflation period and the current acceleration of expansion, of the universe be yet another manifestation of the unwinding of space dragging associated with "near initial" conditions extant at T+10^-43 seconds after the big bang? That must have been some gravity well at BB + 10^-43 seconds.

Sloshing around has to be more accurate a term than what could possibly be forecast by a computer model of something we've no clue about.

Personally, I tend to think DM is a variety of normal matter objects (and maybe black holes made from what at least used to be normal matter). If it's not just a diffuse gas, it's not going to easily be swept around by some 'collision' or another with intergalactic gases.

However, such virtually impossible to see, rather mundane objects aren't going to garner much research money and no pop sci publicity.

RussT
2007-May-19, 09:41 AM
Originally Posted by RussT
http://news.aol.com/topnews/articles...90001?cid=2359

(snip) Hubble found no such thing!!! Hubble CANNOT take pictures of DM!!!



Absolutely true!




So, all of these DM explanations (Including the "Spherical Halos" of DM in galaxies!!!)are based on "Computer Generated" simulations based on N-Body numerical simulations, and THEN they generate a Picture based on these N-body sims and 'super-impose' it onto the Hubble pic of this cluster, and Voila---a "Blue Visual" of their version of what the Exotic Matter is doing.



Et voil&#224;, that&#180;s the explanation! Don&#180;t understand, how people could misunderstand the message.

Thanks dhd40. Obviously there are quite a few misconceptions going on here!

And like I warned here...[BUT, this does reveal the Gross and egregious misrepresentation that ANY 'Picture' (Visual image) trying to represent what DM is actually doing, really is.] They did the same thing with the "Bullit Cluster" too.

Because it causes rediculous statements like this.



The blue glow is probably gas.

And he then has the audacity to say this (because he has seen others do it, which I reported, And will do so every time it is done by anyone in the future)



Your post reveals the gross and egregious misrepresentation of science that can happen when people start mucking about without actually learning the science. And yes, that includes the math.

These kind of dismissive remarks are ludicrous and a personal attack, and that should apply even if they say that "anyone' who can't do GR maths, cannot possibly understand what is really going on.

RussT
2007-May-19, 10:33 AM
You are joking, right? The blue is not a glow, or anything picked up optically. It is the representation of where the dark matter must be as computed by the weak lensing studies.

antoniseb, moderator is still by your name, so why was this allowed to go un-moderated?



Your post reveals the gross and egregious misrepresentation of science that can happen when people start mucking about without actually learning the science. And yes, that includes the math.


It says in the abstract that I linked above (and blob linked] that they used both strong and weak lensing. However, as far as I know, that just means that the lensing is there, NOT that they can actually mathematically extrapolate the lensing itself to show anything about the actual structure of the DM in relation to the galaxies that make up the clusters.

When they say this at the very beginning of the abstract...
[We present a comprehensive mass reconstruction of the z = 0.4 rich galaxy cluster CL0024+17 from Advanced Camera for Surveys data, unifying both strong and weak-lensing constraints.]

that is a N-Body numerical computer generated 'reconstruction', I believe, and when they do that, they are imputting the 'assumed' values for the 'slow' velocity (whatever that might be?), and the 'assumed' WIMP 'mass' (Whatever that might be), and they give the baryonic matter (galaxies) a certain color, and then their N-body 'supposed' non-collisional DM a "Blue" color, and then take that image of the Blue DM after the 'mixing/motion', and superimpose it on the Hubble image of the clusters.

SO, this whole thing is just MADE UP! AND cbacba was basically right above when he said...



what i'd like to know is just how one models mysterious exotic DM when one doesn't know anything about it.

The only thing we really know about the "Exotic Matter", ever since mainstream introduced it (Which I defintely think is one of the things that is right about our universe), as the possible answer to the rotation curves of galaxies and the cluster dynamics...the only thing we really know is that it is "There". There is 'Extra Gravity' there to hold the stars in the galaxies and the galaxies in the clusters. BUT there is NO WAY to tell yet, how fast it is moving, OR what mass it does have!

SO, using the 'Reconstructions', N-body sims, is NOT 'Observations" of anything other than pretty computer images.

And this is even worse than Carlos Frenk's "Galaxy Merger' Sims, where he has 'turned the knobs' enough to be able to use the same word they use in the abstract here..."Remarkable"

At least Arp is using 'pictures' and actual HI mappings of real astronomical objects!

dhd40
2007-May-20, 07:34 PM
(SNIP)

SO, using the 'Reconstructions', N-body sims, is NOT 'Observations" of anything other than pretty computer images. (SNIP)

And reading this, I just wonder whether the N-body sims have been run in 2D or 3D (3D must be very complicated).
This is not at all meant to blame the simulations! We need them, they can be extremely helpful.

trinitree88
2007-May-20, 08:50 PM
It's kind of like taking an old movie still from the King & I with Yul Brynner....and retouching it in the darkroom to make a full head of hair...:shifty::lol: pete.

RussT
2007-May-20, 09:36 PM
It's kind of like taking an old movie still from the King & I with Yul Brynner....and retouching it in the darkroom to make a full head of hair...:shifty::lol: pete.

It is far worse than that! At least in this example you are starting with something that is real...Yul Brynner"s head!

I gave this explanation in post #11. I'll explain below it, and trinitree88, since you seem to understand as much about QM as anyone around, let's see if you are in agreement with the assessment.



That is....That the DM is 'slow' and has a 'mass limit'! AND, the reason they 'made up' this whole version of what they 'think' DM is doing, is because the "Hot" DM models wouldn't allow the "Large Structure" that "Fits" the FLRW model!!!

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


Quote:
In the hot dark matter paradigm, popular in the early eighties, structure does not form hierarchically (bottom-up), but rather forms by fragmentation (top-down), with the largest superclusters forming first in flat pancake-like sheets and subsequently fragmenting into smaller pieces like our galaxy the Milky Way. The predictions of hot dark matter strongly disagree with observations of large-scale structure, whereas the cold dark matter paradigm is in general agreement with the observations.

When they say "Observation" here, they are refering to FLRW 'observation'!

What this is basically saying is that when they tried to model Neutrinos (Hot DM) for the "Large Structure" make up of clusters and galaxy formation, that it simply did not work if the universe is/was expanding Via the FLRW Hubble relation/flow.

SO, what did they do? They (?) hypotheisized/invented a NEW PARTICLE!

The WIMP...Weakly Interacting "Massive" Particle. Thus was 'born' the L-CDM Model.

SO, where is the 'full' family of electron/proton/neutron WIMP's and their Anti-particles???

This finally dawned on me when CM told Bogie in his ISU thread that he needed to come up with the particle/anti-particles for his EEP's!!!

I will explain more when this is answered.

trinitree88
2007-May-20, 11:26 PM
It is far worse than that! At least in this example you are starting with something that is real...Yul Brynner"s head!

I gave this explanation in post #11. I'll explain below it, and trinitree88, since you seem to understand as much about QM as anyone around, let's see if you are in agreement with the assessment.



What this is basically saying is that when they tried to model Neutrinos (Hot DM) for the "Large Structure" make up of clusters and galaxy formation, that it simply did not work if the universe is/was expanding Via the FLRW Hubble relation/flow.

SO, what did they do? They (?) hypotheisized/invented a NEW PARTICLE!

The WIMP...Weakly Interacting "Massive" Particle. Thus was 'born' the L-CDM Model.

SO, where is the 'full' family of electron/proton/neutron WIMP's and their Anti-particles???

This finally dawned on me when CM told Bogie in his ISU thread that he needed to come up with the particle/anti-particles for his EEP's!!!

I will explain more when this is answered.

RussT. I've been around HDM and CDM for a long time. The only thing that shows up in accelerator labs is the Standard Model babies....all three families. The nice thing about accelerators is that you can tune them, like your radio dial, to the exact energy you want. When beams intersect targets, conservation laws, sensitive detectors, and data processing algorithms affirm or deny the properties of your expected creations. That's not to say something strange doesn't show up once in a while...but more often than not, it turns out to be a stray event from an unshielded cosmic ray. Generally speaking coincidence counters filter these out...but a very energetic Z can slip in undetected, react, and create an energy anomaly.. Georg Altarelli . They're just not repeatable, so they're discounted.
Nobody's seen a WIMP, a sneutrino, a sparticle, or any of the 34 predicted babies in a detector yet. It might happen tonight, but I'll bet I look more like Yul before they find another particle (presently my hairline is Jean-Luc Picard...so I don't have far to go..:lol:). Better instrumentation in the space satellite area will yield a few surprises though....that's been consistent, and warrants further funding. Pete.

my title was chopped....feel free

RussT
2007-May-21, 12:28 AM
trinitree88, thanks, that helps a little, BUT you have talked before about SN 1987a and neutrinos detected at 99.99&#37; "c" from that.

So, first, aren't neutrino's existance far more established than WIMPS?

And second, how did they determine that those neutrinos were coming from SN 1987a specifically VS all the other sources from that direction that Neutrinos could be coming from?

trinitree88
2007-May-21, 08:39 AM
trinitree88, thanks, that helps a little, BUT you have talked before about SN 1987a and neutrinos detected at 99.99% "c" from that.

So, first, aren't neutrino's existance far more established than WIMPS?

And second, how did they determine that those neutrinos were coming from SN 1987a specifically VS all the other sources from that direction that Neutrinos could be coming from?

RussT. First, neutrinos are unequivocally known to be real. The Homestake Mine exp., thousands of runs of others.
Second, the water experiments show Cherenkov cones....directionality is implicit....and the SN neutrinos are of higher average energy than a lot of the background sources. Coupled with the timing of the event...9999/10,000 real. pete

Kwalish Kid
2007-May-21, 01:53 PM
What this is basically saying is that when they tried to model Neutrinos (Hot DM) for the "Large Structure" make up of clusters and galaxy formation, that it simply did not work if the universe is/was expanding Via the FLRW Hubble relation/flow.
That seems to be right.

SO, what did they do? They (?) hypotheisized/invented a NEW PARTICLE!

The WIMP...Weakly Interacting "Massive" Particle. Thus was 'born' the L-CDM Model.
From what I've read, the hypothesis of the WIMP seems to predate the large-scale structure tests. The result of these tests, at the time, favoured CDM models. The "L" came later.

SO, where is the 'full' family of electron/proton/neutron WIMP's and their Anti-particles???
This is an excellent question, but not necessarily one that, if unanswered, spells the doom for dark matter. Many of Newton's contemporary detractors argued that, even though the math worked excellently, Newton's theory should be rejected because he couldn't come up with a mechanism for gravity, unlike the vortex theorists. So if we can observe and measure the effects of these particles, especially in circumstances like this where we can see the bending of light that they do (something that places boundaries on the position and distribution of the lens), it seems wrong to get too hung up on specific mechanisms.

Jerry
2007-May-21, 02:09 PM
Et voilā, thatīs the explanation! Donīt understand, how people could misunderstand the message.
(SNIP)
Because the message is not clear as to whether or not there is spectral evidence of matter in the 'blue haze' or not. If there is, the only evidence of dark matter is that the estimated mass of the baryonic matter is to low to cause the distortions.

...Unless the whole article is talking about baryonic dark matter -

transreality
2007-May-21, 11:01 PM
It is quite clear if you read the paper, not just the abstract. The blue haze is visualisation of the mass reconstruction of the cluster image from the lensing study. The circular blue ring without corresponding baryonic mass is quite apparent, DM is hypothesised to explain it.

n-body simulation is used to model the 1D collision of clusters along a filament and if collisionless dark matter is included then a ring like structure is formed, supporting the hypothesis.

There is also nice simulation of the lense properties used to delense background images, which is a neat practical application, and a few pointers at interesting optical properties. Its a nice paper to read.

EDG
2007-May-22, 12:24 AM
Is it actually a 2D ring, or is it really a 3D sphere around the cluster?

trinitree88
2007-May-22, 02:28 AM
Is it actually a 2D ring, or is it really a 3D sphere around the cluster?

EDG. In colorimetry, the extinction of light passing through a cell of path length A, with concentration of absorbing species, B, and extinction coefficient C is ext=A*B*C. For a spherical supernova remnant, your view from outside is going to see a longer path length where your view is tangential along the expanding edges, hence you see a circle of higher density there, and a relatively empty center. So, when they model the DM by using inferred lensing in the cluster, a computer generated sphere of blue color ought to look roughly like a circle viewed from outside, with a low density area in the center....relatively isotropically.
Whether absorbing or scattering light, the path length through the medium plays a big role, so their construct follows from their assumptions....contingent upon those assumptions all being true. pete

EDG
2007-May-22, 08:03 AM
Yep, I understand that's how it works with light... but given that they're basically matching a computer model to the observations, I'd have thought they'd have some idea of the 3D structure of the Dark Matter. I have no clue how DM is supposed to behave, so I don't know if a 2D ring or a 3D sphere is mor reasonable.

transreality
2007-May-22, 08:46 AM
Apparently, at z=3.81 and z=3.95, between 1 and 2 Gyr after the collision each of the cluster cores is surrounded by a donut of mass, and we are viewing in the line-of sight of collision so the donuts are face-on and superimposed.

John Mendenhall
2007-May-22, 04:34 PM
EDG.
Whether absorbing or scattering light, the path length through the medium plays a big role, so their construct follows from their assumptions....contingent upon those assumptions all being true. pete

Much as I dislike the dark matter idea, these folks sure do make a good case for DM.

Jerry
2007-May-22, 04:48 PM
Much as I dislike the dark matter idea, these folks sure do make a good case for DM.

Not really. We know binary star systems that supernova create rings of baryonic matter, matter that we could not see, did not know existed, until the explosion of 1987A. They make a good case that the light from this system is lensed, but can they eliminate ordinary baryonic gases/plasmas as the cause of the lensing?

John Mendenhall
2007-May-22, 04:53 PM
Suggestion, inspired by Groudhead's post #16: Can string theory describe dark matter? If so, does it then limit the number of possible string based universes? Maybe it would avoid string theory predicting too many universes . . .

Grey
2007-May-22, 05:16 PM
It says in the abstract that I linked above (and blob linked] that they used both strong and weak lensing. However, as far as I know, that just means that the lensing is there, NOT that they can actually mathematically extrapolate the lensing itself to show anything about the actual structure of the DM in relation to the galaxies that make up the clusters.Nope. If you read the more detailed piece here (http://hubblesite.org/newscenter/archive/releases/2007/17/full) (or better yet, the full paper (http://arxiv.org/PS_cache/arxiv/pdf/0705/0705.2171v1.pdf)), you'll see that this is exactly what they were doing: using the observed gravitational lensing to map out the matter distribution. You'll also see that at first they thought it must have been an artifact of their analysis technique, and spent a year verifying that, no, it's really there.


that is a N-Body numerical computer generated 'reconstruction', I believe, and when they do that, they are imputting the 'assumed' values for the 'slow' velocity (whatever that might be?), and the 'assumed' WIMP 'mass' (Whatever that might be), and they give the baryonic matter (galaxies) a certain color, and then their N-body 'supposed' non-collisional DM a "Blue" color, and then take that image of the Blue DM after the 'mixing/motion', and superimpose it on the Hubble image of the clusters.Then they did simulations of collisions, and found that, yes, if dark matter behaves the way we theorize, it can produce distributions like what is observed here.


SO, this whole thing is just MADE UP! AND cbacba was basically right above when he said...Nope. This is the standard way to do science. You observe something, you check to see if your current theory works to explain what you see. If it does not, your theory needs some work. If it does (as is true in this case), you've just provided some nice corroborating evidence for your theory.

John Mendenhall
2007-May-22, 05:50 PM
Not really. We know binary star systems that supernova create rings of baryonic matter, matter that we could not see, did not know existed, until the explosion of 1987A. They make a good case that the light from this system is lensed, but can they eliminate ordinary baryonic gases/plasmas as the cause of the lensing?

Wouldn't any kind of baryonic matter be detectable in the infrared? Also, normal matter is sort of sticky. I have problems seeing it distributed in a ring rather than in the center of the cluster.

cbacba
2007-May-27, 01:00 AM
Wouldn't any kind of baryonic matter be detectable in the infrared? Also, normal matter is sort of sticky. I have problems seeing it distributed in a ring rather than in the center of the cluster.

well - if you're dealing with condensed baryonic especially a long way off, it would seem that if it had cooled down (especially if towards the background temperature range) how could you tell there was something there?

Blob
2007-May-27, 03:12 AM
Hum,
baryonic matter may not be not be detectable in the infrared,
but it is not a question about there being more baryonic matter than we can see; this has been shown to be an unlikely solution. Big Bang Nucleosynthesis, for example, indicates that the total amount of normal matter created is only 10 - 5 times less than the amount of matter need to hold observed galaxies and clusters gravitationally together.

“ these are not the baryonic matter we are looking for, move along now.”

RussT
2007-May-27, 11:18 AM
Nope. This is the standard way to do science. You observe something, you check to see if your current theory works to explain what you see. If it does not, your theory needs some work. If it does (as is true in this case), you've just provided some nice corroborating evidence for your theory.

Good to see you back!

But, sorry, I have to disagree. This is NOT the way to do science any more!

Infact, this shows the true levels of what the 'machine' of mainstream is able to get away with. And no one can stop mainstream from continuing to "FIT" everything to Big Bang Cosmology because the 'only' viable alternative is an "Open System" multi-verse that has been absolutely defined as Career Suicide! And even though String/"M" theory has 6 micro dimensions, getting Gravity to 'come through' a dimension can never be shown to work.

When the Big Bang was really in trouble, Alan Guth saved the day, and when they found fully developed galaxies 12/13 billion light years away, they just developed a "MUCH FASTER" star formation rate, and when they found "Young/New" galaxies locally, they just developed a 'slower' star formation rate, and Now with L-CDM, they just make up a whole NEW particle, and really mess up QM!

And why won't anyone answer my question about...where are the full family of WIMP electrons/protons/neutrons and their anti-particles? They must be there because they are still saying there must be a Higgs/Graviton.

Kwalish Kid
2007-May-27, 04:18 PM
Guth has not saved the Big Bang from anything. What do you mean?

RussT
2007-May-27, 10:03 PM
Guth has not saved the Big Bang from anything. What do you mean?

Most of the ramifications that are talked about that Inflation 'solved' are the 'flatness' and 'horizon' problems. That still has a major problem I will address below.

BUT, the biggest 'problem' that Inflation over came (By an ad hoc mathematical "FIX") was the Nearly Infinite High Energy/mass (since E=mc^2) density contained in such a small volume of 'space'!!!

If all the mass/energy of the universe was contained in a singularity, then it could never have overcome the gravity and should have collapsed right back in on itself.

SO, in effect, Inflation 'broke through' the Event Horizon that "SHOULD" be there if 'shrinking the universe down to a point' was a valid gravitational collapse lookback.

So, the whole point is, that naked singularties cannot exist, and they cannot expand because an Event Horizon needs to be there, because that is the very definition of gravitational collapse.

Now, to the horizon/expansion problem. Before 1998, ~73&#37; of the universe was "Missing"! Yep, Baryonic Matter was 4% and Non-baryonic DM (they figured this out when they had to switch to the L-CDM because the HDM couldn't explain the large structure formation) was ~23%.

Miraculously (they will call it good science) in 1998, when Perlmutter (supposedly looking for how much the universe was decelerating) found SN1a (?) on demand, and the luminosity was less bright than it 'should' have been, meant that the expansion was not decelerating, but infact, that the expansion was accelerating. Enter Dark Energy (the convoluted Cosmolgical Constant) and the so called "Repulsive" Anti-Gravity, and the 'other' ~73% that had been 'missing'...amazing!!!

Now, it's no problem that 'space' is expanding (Making more of itself) faster than the speed of light. ACCEPT for this...the farther away clusters are, the faster and faster they must be going, or the whole thing falls apart!!!

What is wrong with that you say? Two things are very wrong with that.

1. The farther clusters are away, the faster and faster that 'space' must be making more of itself, so how can they explain More DE the farther away things are?
2. More importantly, the farther away things are, the farther and farther in the PAST they are.

antoniseb
2007-May-28, 12:14 AM
What is wrong with that you say? Two things are very wrong with that.

1. The farther clusters are away, the faster and faster that 'space' must be making more of itself, so how can they explain More DE the farther away things are?
2. More importantly, the farther away things are, the farther and farther in the PAST they are.

I'm not sure I follow what you are saying here. The further away something is, the more total space is being created between us and it. This does not mean that there must be huge amounts of extra space being created near the edge of the visible universe.

antoniseb
2007-May-28, 12:20 AM
You are joking, right? The blue is not a glow, or anything picked up optically. It is the representation of where the dark matter must be as computed by the weak lensing studies.

antoniseb, moderator is still by your name, so why was this allowed to go un-moderated?

Sorry, I've been busy this week, and didn't notice this. Can you explain what your concern here is? If you have a concern about my moderation, you should bring it up with me or another moderator or administrator by private message. If your concern is something about the content of my post as a member you should click the little reporting triangle. If it is something else, I don't know what you are talking about.

RussT
2007-May-28, 07:59 AM
Sorry, I've been busy this week, and didn't notice this. Can you explain what your concern here is? If you have a concern about my moderation, you should bring it up with me or another moderator or administrator by private message. If your concern is something about the content of my post as a member you should click the little reporting triangle. If it is something else, I don't know what you are talking about.



antoniseb, moderator is still by your name, so why was this allowed to go un-moderated?


Quote:
Originally Posted by Kwalish Kid directed at RussT
Your post reveals the gross and egregious misrepresentation of science that can happen when people start mucking about without actually learning the science. And yes, that includes the math.

antoniseb, this from post 31 is what I was refering to. Kwalish Kid originally posted this in post #12, and I did report it to the mods and didn't recieve a PM NOR was there a warning issued!

Which I then followed up with this in post #30...



And like I warned here...[BUT, this does reveal the Gross and egregious misrepresentation that ANY 'Picture' (Visual image) trying to represent what DM is actually doing, really is.] They did the same thing with the "Bullit Cluster" too.

Because it causes rediculous statements like this.


Quote:
Originally Posted by Kwalish Kid
The blue glow is probably gas.

Originally posted by RussT
And he then has the audacity to say this (because he has seen others do it, which I reported, And will do so every time it is done by anyone in the future)


Quote:
Originally Posted by Kwalish Kid
Your post reveals the gross and egregious misrepresentation of science that can happen when people start mucking about without actually learning the science. And yes, that includes the math.

Originally Posted by RussT
These kind of dismissive remarks are ludicrous and a personal attack, and that should apply even if they say that "anyone' who can't do GR maths, cannot possibly understand what is really going on.

Even if he didn't make such an obvious error showing that he didn't really understand, any arguement should be about the concept/ideas/correlations, and NOT about if someone can do the maths, as that is a personal attack designed to discredit and trivialize what the person does or does not understand about how the universe is working.

antoniseb
2007-May-28, 01:01 PM
I did report it to the mods and didn't recieve a PM NOR was there a warning issued!

Ah, I see. Personally, I have been pretty busy with the non-astronomy parts of my life for the last couple months, and didn't notice your report, but having seen the message string, it was warrented, thanks.

Concerning whether a warning was issued, I'm not sure how you'd know, since most warnings are given by PM. Some are given in thread if there is a reason to make it obvious to others, or a belief that the offender doesn't read PMs. I can't speak for what the other mods have done with this particular case.

RussT
2007-May-29, 12:18 AM
Ah, I see. Personally, I have been pretty busy with the non-astronomy parts of my life for the last couple months, and didn't notice your report, but having seen the message string, it was warrented, thanks.

Concerning whether a warning was issued, I'm not sure how you'd know, since most warnings are given by PM. Some are given in thread if there is a reason to make it obvious to others, or a belief that the offender doesn't read PMs. I can't speak for what the other mods have done with this particular case.

[but having seen the message string, it was warrented, thanks.]

Thanks for the confirmation.

Jerry
2007-May-29, 03:24 AM
Wouldn't any kind of baryonic matter be detectable in the infrared? Usually. Cold H2 is quite transparent in the infrared.

Also, normal matter is sort of sticky. I have problems seeing it distributed in a ring rather than in the center of the cluster.
The rings discovered by supernova 1987A were almost completely invisible before they were illuminated by the supernova. At greater distances, a ring of cold gas would be very difficult to detect, but have enough density to contribute to lensing effects. We shouldn't be surprised by ringed baryonic structures on any scale: binary events produce rings.

Grey
2007-May-29, 01:11 PM
Good to see you back!Thanks.


But, sorry, I have to disagree. This is NOT the way to do science any more!

Infact, this shows the true levels of what the 'machine' of mainstream is able to get away with. And no one can stop mainstream from continuing to "FIT" everything to Big Bang Cosmology because the 'only' viable alternative is an "Open System" multi-verse that has been absolutely defined as Career Suicide! And even though String/"M" theory has 6 micro dimensions, getting Gravity to 'come through' a dimension can never be shown to work.Wait, let's keep this focused on the paper in question. If you have a problem with the science in the paper, you can't show that by just railing against the conspiracy of the mainstream ruthlessly supressing all alternatives. You have to focus on the science.

Do you have a problem with using gravitational lensing as a method of mapping out matter? Gravitational lensing is very well tested in cases where we've got independent measurement of the masses involved. And because the researchers found the result surprising, they checked their work several times to be quite certain. The observation here is that there is a large concentration of matter with a distribution that's quite different from the distribution of visible matter. That's exactly the question of dark matter. Of course, that observation by itself doesn't tell us what that matter is, just that it's there.

As with anything we observe, there's no way to tell with absolute certainty how it got there. The best we can do is explore the possible ways in which it could have formed, and try to see if that's consistent with theory. It turns out that it is in this case. A standard CDM model can easily produce such a distribution of dark matter as a result of a collision. No surprise really, since we see rings of baryonic matter as a result of other collisions.


When the Big Bang was really in trouble, Alan Guth saved the day, and when they found fully developed galaxies 12/13 billion light years away, they just developed a "MUCH FASTER" star formation rate, and when they found "Young/New" galaxies locally, they just developed a 'slower' star formation rate, and Now with L-CDM, they just make up a whole NEW particle, and really mess up QM!What does this have to do with the paper here? If you have a problem with the paper, let's address it.


And why won't anyone answer my question about...where are the full family of WIMP electrons/protons/neutrons and their anti-particles? They must be there because they are still saying there must be a Higgs/Graviton.Are you talking about supersymmetry here? If that turns out to be true, it does provide possible candidate particles for dark matter. But I don't think any physicist would insist that we know supersymmetry holds, nor does it have anything to do with this paper. Rather, this paper discusses an observation of dark matter (by definition: unseen matter detected by its gravitational influence that does not follow the distribution of luminous matter), and a demonstration that the standard CDM model can easily produce such a distribution.

RussT
2007-Jun-01, 01:44 AM
Wait, let's keep this focused on the paper in question. If you have a problem with the science in the paper, you can't show that by just railing against the conspiracy of the mainstream ruthlessly supressing all alternatives. You have to focus on the science.

I covered the 'observation' VS N-Body computer sims thoroughly and then described the entire problem with the L-CDM model as well.



Do you have a problem with using gravitational lensing as a method of mapping out matter?

Yes. As I have stated, the weak and strong 'lens' is there. The Non-baronic DM is there (because of the need for 'extra gravity' to account for the rotation curves of galaxies and the cluster dynamics).

The "Mapping Out" of ANY DM is strictly done with "Sims"!!!

SO, you can call the 'lens' being there an "observation" (Yes, ponderable Matter does curve space) and you can call the DM being there an "observation", BUT you CANNOT count anything that the DM is doing "In a Computer Simulation" as an "Observation"...period!

And as I have also described, this whole L-CDM WIMParticle scenario is "Theory Fitting" to the MAX...worse even than Alan Guth's "Inflation", especially when accompanied by the Lambda/DE finding the "Missing" ~73&#37; of the universe.

Grey
2007-Jun-01, 02:04 PM
I covered the 'observation' VS N-Body computer sims thoroughly and then described the entire problem with the L-CDM model as well.

...

Yes. As I have stated, the weak and strong 'lens' is there. The Non-baronic DM is there (because of the need for 'extra gravity' to account for the rotation curves of galaxies and the cluster dynamics).

The "Mapping Out" of ANY DM is strictly done with "Sims"!!!No. This is not correct. The mapping is not done with computer simulations. Read the paper, and notice that there is no discussion of N-body simulations until section 5, page 26, after they have already done all of the analysis for determining the distribution of dark matter, by looking at the observed strong and weak gravitational lensing. The N-body simulation is not used to determine the dark matter distribution. Instead, the computer simulation is used to make a theoretical prediction from a specific model, to see if that prediction agrees with the observation. And it does.


SO, you can call the 'lens' being there an "observation" (Yes, ponderable Matter does curve space) and you can call the DM being there an "observation", BUT you CANNOT count anything that the DM is doing "In a Computer Simulation" as an "Observation"...period!I am not counting anything from the computer simulation portion of the paper as an observation. I am counting only the analysis of the gravitational lensing as such. So we have an observation that there is a ring of dark matter. We might disagree about what makes up that dark matter, but the observation that there's something there that does not follow the distribution profile of luminous matter is a very solid one. Then we have a theoretical prediction (from a computer simulation) that a galactic collision in a CDM model can easily produce such a structure. Hence, corroboration for the theory, since it's prediction is similar to the observation.


And as I have also described, this whole L-CDM WIMParticle scenario is "Theory Fitting" to the MAX...worse even than Alan Guth's "Inflation", especially when accompanied by the Lambda/DE finding the "Missing" ~73% of the universe.You're supposed to try to fit your theory to the observations. That would be easy for any single observation. The tricky part is that different observations constrain a theory in different ways, so having a single theory that agrees with all the observations isn't so simple. A Lambda-CDM model works very well for the observations that we have to date, however.

RussT
2007-Jun-02, 10:26 AM
Okay, I have re-read the entire paper.

All I can say is wow.

You were right, the first part of the paper was not N-Body sims.

The first part of the paper was all about "Numerical Sims" and quoting numerous other "Numerical Sim" papers with a few modifications and minor (That definitely should have been MAJOR warnings) throughout, along with 'shear statistical analysis' that was based on a "Shear Sim".

The only way they even talked about Dark Matter was when 'putting in' Dark Matter Halos and their 'ellipticity' analysis'



So we have an observation that there is a ring of dark matter.

NO, we do not have any kind of "Observation" of a DM ring. Only that it is there, but not its distibution, mass, or speed!

What we have is a completely 'made up' particle...a WIMP that has been hypothesized 100&#37; as a 'theory saving/fitting' necessity because the 'most likely' 'Exotic Matter'/Non-baryonic DM candidate....the Neutrino was quickly shown NOT to be able to account for the large scale structure in a FLRW universe!

Just like Inflation, and Much faster star formation rates in the Full/old galaxies in the 'early universe', and just like the 'slow star formation rates' in the Young/New galaxies in the local neighborhood. Which is the same kind of tactic they are using against anyone (Thuan) when they come up with the (TRG)Tip of the Red Giant 1/10 Gyr bull!
http://www.astro.uni-bonn.de/~webgk/ws98/thuan_r.html

The things (and especially all Sims) that are being accepted as 'good science' because they have been able to get away with it for so long, has become more than just an annoyance!

Science defining everything so that it MUST adhere to a 'close system' is on the verge (If it hasn't already arrived) of becoming 'Fatally Flawed' just because of that!

I mean think of it...Since Light/photons make gravity, and photons are massless, that means to Unify GR and QFT, the massless light is making the Graviton/Higgs, which is the wave/particle duality that already exists.

Massless anything cannot 'make/give' mass to something. Something is wrong with E=mc^2, which is simply the Einstein did NOT know anything about "Exotic Matter", and therefore E=mc^2 only applies to Baryonic Matter. E=mc^2 does NOT apply to Massless Non-ionizing photons and Non-Baryonic Matter...UNTIL?

Something's wrong somewhere...don't ya think?

Michael Noonan
2007-Jun-02, 12:25 PM
Okay, I have re-read the entire paper.

Something's wrong somewhere...don't ya think?

Hi there,
If you need help with things wrong maybe this will help link (http://www.bautforum.com/showthread.php?p=999881#post999881)
Just for fun, cheers Mike :)

Nick4
2007-Jun-07, 01:01 AM
How did they get DM to 'shine' BLUE?

If you look at the pic you can see a kind of dark ring around the center of the image. i think thats the dark matter ring not the blue.

Nick4
2007-Jun-07, 01:02 AM
This is a really beautiful image though.

Grey
2007-Jun-08, 05:50 PM
Okay, I have re-read the entire paper.

All I can say is wow.

You were right, the first part of the paper was not N-Body sims.

The first part of the paper was all about "Numerical Sims" and quoting numerous other "Numerical Sim" papers with a few modifications and minor (That definitely should have been MAJOR warnings) throughout, along with 'shear statistical analysis' that was based on a "Shear Sim".

The only way they even talked about Dark Matter was when 'putting in' Dark Matter Halos and their 'ellipticity' analysis'Perhaps you don't understand what's going on in a weak lensing analysis. It necessarily requires a statistical element, including numerical analysis techniques. The math is just too complex. You have hundreds or thousands of data point, so you can't just solve directly for the mass distribution. That should be no surprise, since even a three body problem can't be solved analytically, only numerically. Does that mean that they might have made a mistake? Sure. But does that mean that we can simply discount their results without actually showing what was wrong with their analysis? Certainly not. Remember, numerical analysis techniques are what allow us to track the motions of the planets and send probes to visit them.

You don't get to dismiss someone's work just because they used a computer to help work out the math. As with any science, you actually have to do the work of showing where there was a problem. And if you'll note, they were initially concerned themselves that what they were seeing might just be an artifact of their data analysis. That's why they spent a year going over it in detail, trying other possible analysis methods, correlating it to the strong lensing data (which isn't as statistical in nature), and making sure that what they were seeing was genuinely present in the data itself.


NO, we do not have any kind of "Observation" of a DM ring. Only that it is there, but not its distibution, mass, or speed!How can we know anything is there at all if we don't know its distribution or mass? That doesn't make any sense.


What we have is a completely 'made up' particle...a WIMP that has been hypothesized 100% as a 'theory saving/fitting' necessity because the 'most likely' 'Exotic Matter'/Non-baryonic DM candidate....the Neutrino was quickly shown NOT to be able to account for the large scale structure in a FLRW universe!Oops, wait. Now you're moving beyond the observations to theory. Everyone admits that we don't know what dark matter is made of, and this paper is no different. We do some things that it can't be, and we've got some good information on how it has to behave if it is going to explain what we see. And it generally turns out, as in this case, that the properties that would allow it to explain other observations don't need to be changed at all in order to also explain this new observation. That's pretty good corroborating evidence that there really is something with those properties accounting for all of these observations. That still doesn't mean we know what it is, of course, but nobody is claiming that we do. Only that we've got some possibilities that would work.


Massless anything cannot 'make/give' mass to something. Something is wrong with E=mc^2, which is simply the Einstein did NOT know anything about "Exotic Matter", and therefore E=mc^2 only applies to Baryonic Matter. E=mc^2 does NOT apply to Massless Non-ionizing photons and Non-Baryonic Matter...UNTIL?That's interesting. You're criticizing the mainstream for proposing an unobserved particle to explain the observations. Yet here, you're doing exactly the same thing! You're suggesting that some kind of "exotic matter" exists, which has not been directly observed, but which does not obey E = mc2. Well, there's not really anything stopping you from proiposing such an idea of course. The tricky part is, you'll have to show that it actually explains the observations. For example, how does this exotic matter work in this instance to make it appear as far as gravity is concerned that there is matter distributed in a ring in the system being looked at here. Don't forget to be quantitative in your analysis; the paper should have enough details about the observations themselves to give you a good starting point.

RussT
2007-Jun-11, 01:08 AM
Originally Posted by RussT
Okay, I have re-read the entire paper.

All I can say is wow.

You were right, the first part of the paper was not N-Body sims.

The first part of the paper was all about "Numerical Sims" and quoting numerous other "Numerical Sim" papers with a few modifications and minor (That definitely should have been MAJOR warnings) throughout, along with 'shear statistical analysis' that was based on a "Shear Sim".

The only way they even talked about Dark Matter was when 'putting in' Dark Matter Halos and their 'ellipticity' analysis'.



Perhaps you don't understand what's going on in a weak lensing analysis. It necessarily requires a statistical element, including numerical analysis techniques. The math is just too complex. You have hundreds or thousands of data point, so you can't just solve directly for the mass distribution. That should be no surprise, since even a three body problem can't be solved analytically, only numerically. Does that mean that they might have made a mistake? Sure. But does that mean that we can simply discount their results without actually showing what was wrong with their analysis? Certainly not. Remember, numerical analysis techniques are what allow us to track the motions of the planets and send probes to visit them.

But I have shown what is wrong all along...'Numerical "SIMS", "Shear "SIMS", "N-body "SIMS"...and ALL of those "SIMS" input 'assumed' values for WIMPS!!!

AND, as I said, after re-reading the entire paper, the only way they talk about DM is by adding into their "SIMS", DM Halo's, which were developed the same exact way...Through "SIMS"!!!



Remember, numerical analysis techniques are what allow us to track the motions of the planets and send probes to visit them

And this even proves my point! This says NOTHING about DM, does it?



And if you'll note, they were initially concerned themselves that what they were seeing might just be an artifact of their data analysis. That's why they spent a year going over it in detail, trying other possible analysis methods, correlating it to the strong lensing data (which isn't as statistical in nature), and making sure that what they were seeing was genuinely present in the data itself.

This is NOT an arguement for being correct!!! They could take a milenium to study and re-study this and since they are still using the same assumed WIMP values IE; 'slow' and 'x massive', they would still be finding exactly what they are *looking for*, which is precisely why the L-CDM model was developed, just like Inflation!



Oops, wait. Now you're moving beyond the observations to theory.

As I have stated (I believe in this thread and others) the need for "Exotic Matter"/Non-Baryonic DM to hold stars in their galaxies (Galaxy rotation curves) and galaxies in their clusters (Cluster dynamics) is NOT Big Bang (Or any theory) dependent. Those analysis is just showing that "Extra Gravity" must be present. Which is precisely why mainstream came up with "Exotic Matter" as the hypothesized "Extra Gravity".

BUT, as soon as anyone starts trying to show how that 'extra gravity' is moving/distibuted, it does become a "Global" consideration, and becomes 'theory dependent'.

Apparently, I am one of the few who understands this. As can be evidenced here...
http://www.bautforum.com/showthread.php?t=60172

Even professionals don't really appreciate the real differences between Dark Matter and Dark Energy, and most Anti-Big Bangers just rail against both.



That's interesting. You're criticizing the mainstream for proposing an unobserved particle to explain the observations.

Yes I am. And as I have repeatedly said, the words 'observation' and 'detection' have become completely convoluted!

To be continued;

Grey
2007-Jun-11, 03:22 PM
But I have shown what is wrong all along...'Numerical "SIMS", "Shear "SIMS", "N-body "SIMS"...and ALL of those "SIMS" input 'assumed' values for WIMPS!!!No, that's wrong. Look at the first half of the paper again. They make absolutely no assumptions whasoever about what the mass comes from. The early "simulations" are numerical analysis techniques to determine the mass distribution, but they don't even assume that the mass causing the lensing is composed of WIMPS or similar particles, let alone what properties those particles might have. If you disagree, find me a reference from the first part of the paper where they use any parameters or assumptions about what the matter they are observing is.


Remember, numerical analysis techniques are what allow us to track the motions of the planets and send probes to visit them.
And this even proves my point! This says NOTHING about DM, does it?What this shows is that numerical analysis techniques are valid methods of determining the mass, distribution, and motion of objects. It does that sufficiently well that we can do some pretty detailed navigation using the results. So how does that support your claim that such techniques are an invalid method of measuring mass or mass distribution?


This is NOT an arguement for being correct!!! They could take a milenium to study and re-study this and since they are still using the same assumed WIMP values IE; 'slow' and 'x massive', they would still be finding exactly what they are *looking for*, which is precisely why the L-CDM model was developed, just like Inflation!Nope. You might want to read the paper yet again, since it looks like you still misunderstood the first part. There are no[i/] assumptions about the particles making up the matter responsible for the lensing in the first part of the paper. They do not assume that they are slow, or that they have a specific mass, or how they might interact, or anything else. If you wish to continue to dispute this, give a reference to show that they do.


That's interesting. You're criticizing the mainstream for proposing an unobserved particle to explain the observations.
Yes I am. And as I have repeatedly said, the words 'observation' and 'detection' have become completely convoluted!This quote is really taken out of context, and you have not replied to the second part, which you omitted here. Let's look at it again.


That's interesting. You're criticizing the mainstream for proposing an unobserved particle to explain the observations. Yet here, [I]you're doing exactly the same thing! You're suggesting that some kind of "exotic matter" exists, which has not been directly observed, but which does not obey E = mc2.I've added emphasis to the part that you left out. Let me say it again: you're doing the same thing that you're saying is the problem with the mainstream explanation. You're proposing a type of matter which has not been directly observed as a solution to the additional gravitational influences that are observed. You're further claiming that this new type of matter violates relativity, an even more extreme property than the mainstream model of dark matter. So if you can introduce a new type of matter that is not directly observed to explain things, why can't someone else? Well, the answer is, of course, that there's nothing wrong with doing so, but you'd better be able to show (quantitatively, of course), that your model actually works to explain the observations. So, let's have it. If your model can match the observed rotation curves for various galaxies and the dynamical behavior of clusters better than a CDM model, show that quantitative agreement. And stop saying that the mainstream model has to be wrong because it requires some new type of matter when your model also requires some new type of matter.

Jerry
2007-Jun-15, 08:25 AM
arXiv:0706.1976 [ps, pdf, other] :
Title: Tidal dwarf galaxies as a test of fundamental physics
Authors: G. Gentile, B. Famaey, F. Combes, P. Kroupa, H. S. Zhao, O. Tiret
Comments: Submitted to A&A Letters, 4 pages, 3 figures


Within the cold dark matter (CDM) framework tidal dwarf galaxies (TDGs)cannot contain dark matter, so the recent results by Bournaud et al. (2007)that 3 rotating TDGs do show significant evidence for being dark matter dominated is inconsistent with the current concordance cosmological theory unless yet another dark matter component is postulated.

We confirm that the TDG rotation curves are consistent with Newtonian dynamics only if either an additional dark matter component is postulated, or if all 3 TDGs happen to be viewed edge-on, which is unlikely given the geometry of the tidal debris. We also find that the observed rotation curves are very naturally explained without any free parameters within the modified Newtonian dynamics (MOND) framework if inclinations are adopted as derived by Bournaud et al. We explore different inclination angles and two different assumptions about the external field effect.

The results do not change significantly, and we conclude therefore that Newtonian dynamics has severe problems while MOND does exceedingly well in explaining the observed rotation curves of the 3 TDGs studied by Bournaud et al.

So the rare splatter galaxies prove the existance of Dark Matter, while dwarf galaxies prove MOND phenomenology holds true in three other collisions.

It may take a while to sort this out.

Michael Noonan
2007-Jun-15, 02:32 PM
arXiv:0706.1976 [ps, pdf, other] :
Title: Tidal dwarf galaxies as a test of fundamental physics
Authors: G. Gentile, B. Famaey, F. Combes, P. Kroupa, H. S. Zhao, O. Tiret
Comments: Submitted to A&A Letters, 4 pages, 3 figures


So the rare splatter galaxies prove the existance of Dark Matter, while dwarf galaxies prove MOND phenomenology holds true in three other collisions.

It may take a while to sort this out.




What I find so interesting about dark matter is that it is present in our galaxy.

Two it appears to be present in all galaxies
Three all galaxies have super massive black holes
Four we can not detect the dark matter in these galaxies
Five we can not detect the dark matter in our galaxy

Therefore as we don't see it nor can we detect here with us we assume it is not present with us, most interesting.

Most assuredly not a thread hijack, just a curious observation.

Kwalish Kid
2007-Jun-15, 04:10 PM
So the rare splatter galaxies prove the existance of Dark Matter, while dwarf galaxies prove MOND phenomenology holds true in three other collisions.

It may take a while to sort this out.
There isn't much to sort out. If you look at the paper that Gentile et al. cite as the impetus for their research, you'll see that these three galaxies not only can be explained by a CDM model, but that they can be used to measure the amount of baryonic matter present in the progenitor galaxy that is in a form that doesn't radiate electromagnetic radiation at detecable levels or that is traced by visible elements.

Gentile et al. claim that, "The dark matter required in Newtonian dynamics implies a large amount of unseen baryonic matter, which is very unconventional in the CDM context." However, I see no reason for this to be the case. There should be some dark baryonic matter in these galaxies and we do not yet know the specifics of its distribution.

iantresman
2007-Jun-15, 09:10 PM
What I find so interesting about dark matter is that it is present in our galaxy.

This morning I discovered a dent in the body of our car which I suspect is due to dark matter. It's presence in our village was further corroborated by a neighbor who says that their wife drove off the road after an "unknown force" cause her to swerve. I plan to do a survey as I suspect that such dark matter tends to accumulated along roads and near cars.

transreality
2007-Jun-18, 01:28 AM
... Four rings of Dark Matter found around automobile.

chriscurtis
2007-Jun-20, 01:44 AM
This thread is brilliant. Like Cougar, I just about fell off my chair reading the interchange around Zahl's comments.

It's pretty obvious there's no such thing as dark matter/energy and that spacetime is simply a sum of probabilities of finding energy/matter. The reason gravity seems to be attractive is that that probabilities are positive numbers. Voids between galaxies seem to be expanding because the probability of finding particles there is reducing over time.

Humans, hey. They can't see the wood for the trees.

It's all simple or it wouldn't work ;-)

chriscurtis
2007-Jun-20, 01:45 AM
I have no real evidence for any of that of course, it just feels right and if it good enough for G W Bush... :-)