Fresh theories about dark matter

Fresh theories about dark matter
An image comparing the data showing the many galaxies and the X-ray emission from the hot gas (left) with the model of the hot gas (right). The "comet" shape of the X-ray data is well reproduced by the model

Tom Broadhurst, the Ikerbasque researcher in the Department of Theoretical Physics of the UPV/EHU, together with Sandor Molnar of the National Taiwan University and visiting Ikerbasque researcher at the UPV/EHU in 2013, have conducted a simulation that explains the collision between two clusters of galaxies. Clusters of galaxies are the biggest objects that exist in the universe. They are collections of hundreds of thousands of galaxies pulled together by gravity.

In general, galaxy clusters grow in size by merging with each other to become increasingly larger. Gravitational forces cause them to slowly come together over time despite the expansion of the universe. The system known as "El Gordo", the biggest known of galaxies, is in turn the result of the collision between two large clusters. It was found that the collision process compresses the gas within each cluster to very high temperatures so that it is shining in the Xray region of the spectrum. In the Xray spectrum this gas cloud is comet shaped with two long tails stretching between the dense cores of the two clusters of galaxies. This distinctive configuration has allowed the researchers to establish the relative speed of the collision, which is extreme (~2200km/second), as it puts it at the limit of what is allowed by current theory for .

These rare, extreme examples of clusters caught in the act of colliding seem to be challenging the accepted view that dark matter is made up of heavy particles, since no such particles have actually been detected yet, despite the efforts being made to find them by means of the LHC (Large Hadron Particle Collider) accelerator in Geneva and the LUX (Large Underground Xenon Experiment), an underground dark matter detector in the United States. In Tom Broadhurst's opinion, "it's all the more important to find a new model that will enable the mysterious dark matter to be understood better". Broadhurst is one of the authors of a wave-dark-matter model published in Nature Physics last year.

This new piece of research has entailed interpreting the gas observed and the dark matter of El Gordo "hydrodynamically" through the development of an in-house computational model that includes the dark matter, which comprises most of the mass, and which can be observed in the Xray region of the visible spectrum because of its extremely high temperature (100 million kelvin). Dr Broadhurst and Dr Molnar have managed to obtain a unique computational solution for this collision because of the comet-like shape of the hot gas, and the locations and the masses of the two dark matter cores that have passed through each other at an oblique angle at a relative speed of about 2200 km/s. This means that the total energy release is bigger than that of any other known phenomenon, with the exception of the Big Bang.

Explore further

Galaxy clusters collide—dark matter still a mystery

More information: "Hydrodynamical Solution for the 'Twin-Tailed' Colliding Galaxy Cluster 'El Gordo.'" Astrophysical Journal, ApJ 800 37. DOI: 10.1088/0004-637X/800/1/37
Citation: Fresh theories about dark matter (2015, May 15) retrieved 14 October 2019 from
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May 15, 2015
jalmy: How it plays out = you see distinct emission lines correlating to the annihilation of matter and anti-matter. It's very well known how to observe anti-matter in the universe.

Ren82: On very large scales, the universe expands. On small scales where mass is the dominant form of energy, that mass gravitationally interacts, and space does not expand. Imagine it like a loaf of raisin bread. The raisins don't expand, even though the dough expands the distance between them.

May 15, 2015
Bigger, Darker, Dark Matter.

Extradimensional mumbo jumbo.

What is Pi in planck units?

Define the least amount of energy that a photon could represent in respect to planck units.

If the radius is 1 plack unit, or the diameter maybe, what does the "math" to determine that?

They don't even know what ordinary matter is in terms of spacial reality, and they're trying to define some pixie dust that supposedly exists ONLY in every other Galaxy, and doesn't at all exist in the Milky Way, based on observations and common sense.

Black holes have no hair, he said.

White holes have infinite "hair" she said.

If you were adjacent to a white hole which did not have critical mass to just collapse to a black hole, what would you "see"?

Radiation and particles of every "type"? Or would it settle on one type of radiation or particle and emitt only that? If so, could you necessarily distinguish it from a normal "star" over human observation time scales?!?

May 15, 2015
Physicists are starting to realize the notions of dark matter and the dark matter particle are incorrect. They are referring to the mass which fills 'empty' space as the 'dark mass' in order to distinguish it from the baggage associated with dark matter.

'Dark Energy/Dark Mass: The Slient Truth'

"That is, all that we are certain about [is] the dark mass, not dark matter, let alone to say about the dark 'particle'."

Particles of matter move through and displace the dark mass, including 'particles' as large as galaxies and galaxy clusters.

The Milky Way moves through and curves spacetime.

The Milky Way moves through and displaces the dark mass.

The state of displacement of the dark mass is curved spacetime.

May 15, 2015
"Hydrodynamical solution" to explain this plasma, in a word? Fail! Let's add an acronym too, GIGO!

May 15, 2015
What a terrible lede. These researchers aren't proposing any 'fresh theories' for dark matter.

May 15, 2015
Take your "in-house computational model that includes the dark matter." Change it so that...

Dark-Matter = Anti-Matter, and
Anti-Matter = Anti-Gravity

See how that plays out.

that certainly wouldn't explain the angular momentum anomaly seen in spiral and elliptical galaxies.

May 15, 2015
'...have conducted a simulation that explains...' This always bothers me. If we don't know what DM is, what it is made of...or worse doesn't exist at all, how does one allow for it in a 'simulation'...maybe I just got out of the wrong side of the bed this morning and unable to imagine some 'impossibilities' before lunch.

May 16, 2015
The most puzzling part of this colliding galaxy cluster picture, is that it makes no connective link to DM.

After a first read of the article you think you must have missed the paragraph which in some inextricable manner hypothesizes these galaxy clusters are colliding due to the presence of DM, but it doesn't say that.

Next you go back & reread it thinking they were interpreting some x-ray or gamma ray spectroscopy emission that could be caused by DM but they didn't do that either.

So next you start thinking maybe they're trying to say that the 2200 km/sec rate of speed has something to do with DM, but they didn't do that either.

So what exactly is it they are hypothesizing for the effects of DM in this galaxy cluster collision?................ Maybe if this guy would just expend a little kinetic energy & head out there a bring back a barrelfull of this stuff that he could show us, he could then find some credibility for the zero DM content of this article.

"These rare, extreme examples of clusters caught in the act of colliding seem to be challenging the accepted view that dark matter is made up of heavy particles--"

Since it's merely stated but not explained, can anyone infer why this observation seems to be challenging the heavy particle view of dark matter?

May 16, 2015
deleted second copy of my post that system made by itself

May 16, 2015
Lots of negative comments about the quality of this article. However in fairness, PhysOrg before it was 'upgraded' used to have a place at the bottom of all articles to rate, one to five stars. Now that is gone and the only way to rate is to say it in the text. That identifies the raters as if that could be done by the server that receives all comments anyway. Having to discourse about quality writing wastes space and the commenter's time when that rating box that did it all could have been kept.

That said, the ideas are food for thought. I personally lean toward small particles flying 'under the radar' or maybe transdimensional particles. Of course if the 'standard model' could be re-modded into three dimensions, which I find a certain 'horse sense' engineering background to reject nonsense answers unless absolutely necessary or some logic is found to make the silly make sense.

We also need to realize that time is 3-D as well!!

May 16, 2015
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May 16, 2015
If the radius is 1 plack unit, or the diameter maybe, what does the "math" to determine that?
See Natural units, under the section "Systems of natural units" see "Planck units".

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