GOTCHA: A galaxy cluster dominated by dark matter
Image: X-ray: NASA/CXC/M. Markevitch et al.; Optical: NASA/STScI, Magellan/U. Arizona/D. Clowe et al.; Lensing Map: NASA/STScI, ESO WFI, Magellan/U. Arizona/D. Clowe et al.
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The generic line on dark matter is that nobody knows what it is because nobody has seen it. The former claim remains unassailable—any number of hypothetical particles could be dark matter. As to whether or not anybody has seen it, scientists are as divided as ever, and the discourse among rival dark matter hunters is getting chippy.
The controversy centers on an Italy-based research group that runs DAMA, a particle detector that the researchers have claimed for years is picking up dark matter particles. But the group has been secretive about its data, critics say, and physicists have by and large remained skeptical. Indeed, in April a top experimental collaboration known as XENON100 reported findings that appeared to rule out the possibility that DAMA’s signal came from dark matter.
At issue is not the data so much as what they mean. If dark matter rings the galaxy as theory predicts, Earth should be orbiting through a sea of dark particles, and DAMA should detect this as the yearlong ebb and flow in the “ambient particle environment.” For more than 10 years now, DAMA has been registering blips that fit this pattern. “I think everyone would agree at this point that they see a signal,” astronomer Mario Livio of the Space Telescope Science Institute in Baltimore said in May at a dark matter symposium. “The question is, What is it?”
DAMA researchers have now found, at last, some preliminary validation of their claim to have seen signs of dark matter. A Minnesota detector called CoGeNT has registered seasonal blips akin to what DAMA has seen, physicist Juan I. Collar of the University of Chicago said at the symposium. He cautioned that the data are preliminary but charged that competitors—including one whose results he derided as “pure, weapons-grade balonium”—have been too quick to dismiss DAMA.
CoGeNT may turn out to be the ally DAMA has long lacked, but Collar maintains that he is not taking sides. “Maybe DAMA’s wrong, maybe they’re right, but we have to remain neutral,” he said. “I find myself caught between the believers and heathens.” The upshot: the field of dark matter research remains as murky as ever.
This article was originally published with the title International Particle of Mystery.
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26 Comments
Add CommentThe cute image replete with the caption "GOTCHA: A galaxy cluster dominated by dark matter" is an x-ray image of the partially merged 'Bullet Cluster'. It is the 'poster child' of proposed observational evidence of dark matter despite being only very indirectly inferred by several complex analyses of actual data.
Reply | Report Abuse | Link to thisThe pink colored areas do not even indicate the inferred presence of dark matter: they illustrate the x-ray emissions produced by the (ordinary matter) gaseous intergalactic mediums of two merging galaxies. These gaseous regions are thought to have been slowed by the friction of their material interactions and resulting emissions.
I won't even go into the proposed evidence for dark matter not even shown in this image, since you missed it completely, except to point out that it is though to be coincident with the two clusters' galaxies, both of which are thought to have been slowed only by their gravitational interactions.
This article states:
Reply | Report Abuse | Link to this“If dark matter rings the galaxy as theory predicts, Earth should be orbiting through a sea of dark particles…”
Particle physicists seem to expect that there is a planar disc of dark matter coincident with the observed galactic disk of ordinary stars and gasses. While this seems to be a reasonable expectation for particles that interact gravitationally, the inferred requirement for galactic dark matter is based on the discrepancy between observed rotational velocities of galactic disc objects as a function of their distance from the galactic center and the expectations of astronomers based on Keplerian rotational curves illustrating the laws of planetary motion.
Those laws specify that rotational velocities should diminish as a function of distance from the galactic center, but objects within the planar galactic discs of spiral galaxies maintain a generally flat or even increasing rotational curve. Galactic dark matter is intended to provide additional mass at the galactic periphery to account for the observed increased peripheral rotational velocities in relation to the velocities near the inner circumference of the disc.
While the presence of dark matter within the galactic disc cannot be precluded, it would not meet the intended requirements for additional mass. It is currently estimated that the amount of mass provided by dark matter configured within the peripheral dark matter halo (located between 100,000 and 300,000 light years from the galactic center) is about 10 times the mass provided by ordinary galactic matter. ref. Battaglia et al. (2005), "The radial velocity dispersion profile of the Galactic halo: constraining the density profile of the dark halo of the Milky Way", http://www.arxiv.org/abs/astro-ph/0506102
That research identifies more than 200 objects comprised of ordinary matter that orbit the Milky Way within its visible matter halo. They include satellite galaxies, globular clusters and old stars - discrete objects that do comply with the Keplerian rotational curve. I suggest that these objects in effect each independently orbit the collective mass of the galactic disc and bulge similarly to the sparse planets orbiting the Sun, which contains 99.86% of total Solar system mass.
Conversely, I suggest that the objects within the galactic plane do not each independently orbit any central massive object - they collectively form a loosely bound self-gravitating rotating mass. IMO, there is no requirement for additional mass to account for the rotation of galaxies.
Perhaps Dark Matter interacts with gravity in the opposite way matter does? Has there been any research on that?
Reply | Report Abuse | Link to thisAnd of course all the researchers who built the models upon which the requirement for dark matter was built were too dumb to understand that the galaxy isn't a point mass and build their models on the basis of mutual self-gravitation. Give me a break.
Reply | Report Abuse | Link to thisDo you really think I'm so dumb? The definitive reference that established the perceived requirement for galactic dark matter:
Reply | Report Abuse | Link to thisV. Rubin, N. Thonnard, W. K. Ford, Jr, (1980), "Rotational Properties of 21 Sc Galaxies with a Large Range of Luminosities and Radii from NGC 4605 (R=4kpc) to UGC 2885 (R=122kpc)", Astrophysical Journal 238: 471, Bibcode 1980ApJ...238..471R, doi:10.1086/158003,
http://adsabs.harvard.edu/abs/1980ApJ...238..471R
For additional research, I suggest:
"Rotating thin-disk galaxies through the eyes of Newton",
http://www.arxiv.org/abs/1007.3778
"Is Dark Matter Present in NGC 4736? An Iterative Spectral Method for Finding Mass Distribution in Spiral Galaxies",
http://www.iopscience.iop.org/0004-637X/679/1/373/
These papers also contain references to libraries of supporting materials.
BTW, the accomplished astronomers who established that perceived requirement for galactic dark matter within the astronomical community did not model galactic gravitation at all.
Reply | Report Abuse | Link to thisThey simply identified the observational discrepancy of stellar rotational velocities with the expected diminishing rotational velocities specified by "Keplerian rotation charts". From this it alone was concluded that some additional, undetected mass must be present. Please refer to the Vera Rubin et al research reports.
Wilkinson Microwave Anisotropy (WMAP) SHOWS DARK MATTER?
Reply | Report Abuse | Link to thisDark matter, what is it? Have Physicists been looking in all the wrong places, yes.
A new theory predicts Dark matter to be a subatomic particle that has Pooled in the universe, it's properties give it anti-gravity effects so as to push on all matter from the edge of the Universe.
Positrons and antimatter subatomic particles are what Physicists have call Dark matter. When high altitude thunderstorms are photographed with high speed cameras they have captured lighting within these storms create vast amounts of Positrons from hydrogen atoms. Just as CERN creates positrons lighting does the same but in enormous amounts, the Positrons race up the electromagnetic field of Earth and into outer space.
Antimatter being polar opposite of gravity races to the edge of the universe collecting in A large pool attracted to each other, just as matter clumps together to make planets or Stars so does anti-matter clump in the same way.
Currently Physicists have been unable to detect this ghost with particle detectors but they may have already found it but just did not realize it.
Physicists have been chasing the ghost of Dark Matter when the real particle has been part of the atomic family of quirks all along. The particles that are emitted by all types of planets with lighting around the Universe for 13.5 billion years. The amount of anti-matter within the Universe would be solvable based on the amount of (-) negative weight in the Universe.
The Pool of anti-matter should show up on the Wilkinson Microwave Anisotropy (WMAP) as a large cool area, have you seen this image on the WMAP? Positrons along with all subatomic particles that make up the same family will theoretically coalesce into an anomaly, a Pool of cool blue in the Universe.
Ronald Nussbeck
And what about "MOND" Modyfied Newtonian Dynamics ?
Reply | Report Abuse | Link to thisCorrection: the term "intergalactic mediums" should be changed to "intracluster mediums".
Reply | Report Abuse | Link to thisCorrection to comment #6: the term "Keplerian rotation charts" should be changed to "Keplerian rotation curves".
Reply | Report Abuse | Link to thisHi James,
Reply | Report Abuse | Link to thisGood to see you alive and kicking in the thought ring, at first I thought you had only data to refer to, but by following all your posts I understood that you indeed are in posession of a certain quantum of data (relatively big or small) but that you have a real honest intention to attribute to the fondamental scaience with the consciousness of your own, which is in my view tha best way to do, you are just a piece of the mosaic, don't get frustrated by bewerto (who the hell is he ?).
keep on thinking
Wilhelmus
Yes - just trying to help. Thank you very much, Wilhelmus.
Reply | Report Abuse | Link to thisWilhelmus de Wilde,
Reply | Report Abuse | Link to thisYes, modified Newtonian dynamics (MOND) is a hypothesis that proposes a modification of Newton's law of gravity to explain the galaxy rotation problem is now solved?
On December 14, 2009 Nasa's Fermi satellite was flying over Egypt, the spacecraft intercepted a particle beam from a terrestrial gamma-ray flash which occurred over it's horizon. Fermi's Gamma-ray burst monitor detected the signal of positrons annihilating on the spacecraft, twice, some of the particles reflected off a magnetic mirror point and returned. Studies of lighting storms using high-speed cameras reveal a whole world of activity in the upper atmosphere that no one expected, anti-matter particles created high above ordinary storm clouds by bolts of lightings. These Terrestrial Gamma-ray flashes send beams of anti-matter arcing through the Earth's atmosphere in thunderstorms as high as 100 kilometers and are sometimes referred to as Blue Jets. It is now believed that as many as 500 or more Gamma-ray flashes happen everyday with thunderstorms coughing Positrons (anti-electrons) up the Earth's magnetic field and into orbit around our Galaxy.
Positrons (anti-electrons) are in fact polar opposite of electrons which are gravitational bound by matter.
Dark matter theory suggests that each galaxy contains a halo of an as yet unidentified type of matter that provides an overall mass distribution different from the observed distribution of normal matter. This dark matter modifies gravity so as to cause the uniform rotation velocity data. This is a true statement but only in terms that positrons and anti-electrons "Push" and "Halo" around galaxy's outer electromagnetic field created by Black Holes. Many of these Positrons escape beyond the Galaxy's grip and have pooled on the edge of the Universe and can be seen in the WMAP.
Ronald Nussbeck
There is no dark matter, just lots of ordinary matter you haven't been able to find yet.
Reply | Report Abuse | Link to thisThank yoy Ronnie for the clear explanation of how about the Standard Model has to be interpreted by the observations we do.
Reply | Report Abuse | Link to thisThis is only one way to try to explain the universe with the knowledge that we have untill this very moment, of course explications can be made this way, but also they can be made in another way, and perhaps tomorrow we will have to change all of our theories.
Gravitation is one of the so called 4 forces that we "contacted" in our universe, but as a matter of fact this gravitation is NOT appliquable to the quantum scale, which is in my humble opinion very logic , because how should gravitation be the result of a wave function ???, (being incertainity of position and speed)it is only after "observation" that the wave function collapses, so before that : NO GRAVITATION, it is so the observer that creates gravitation (?!!!).
This is how I try to explain the difference between these two scales and their fundamental differences. Trying to write a TOE may be possible but not in the way to unify forces that operate only in different scales, we have to try to unify these scales but unifying does not mean here that all these scales have the same laws to attend to, they each have their proprties and laws of their own and their mosaic creates the total UNITY that we are conscious of.
keep on thinking
Wilhelmus
STANDARD MODEL REPLACED BY THEORY OF EVERYTHING (TOE) TO FORM THE BASIS FOR ANTIGRAVITY EQUATION
Reply | Report Abuse | Link to thisUsing the newest scientific investigative direct imaging diagnostic tool now available, that may be able to create
images on a much deeper level from microscopic to unlimited enlargement capabilities than has ever been attained or seen before.
That will give scientists and Planetary researchers a much better look at the Chemical compounds found in the Universe. The name of this new microscopic imaging technology is named:"ORIE". Which is the acronym
meaning;" OPTICAL- REMOTE - IMAGING - ENHANCEMENT "
USING THIS TOOL TO ESTABLISH THE TOE
Chemical compounds are seen as wavelengths by the human eye between 390 nm 750 nm and is called visible light. Chemical compounds contain identity markers know as Wavelengths that can now be traced back beyond the atom to the Quantum level in the form of color emissions wavelengths. The Quantum wave should be considered the instructions for alignment of Protons, Electrons, Positrons, Quarks and so on in the nuclei of the atom. During orbital alignment these Atomic and Subatomic particles form the basis for rotation, alignment, gravity and antigravity with in the Atom, this is ultimately responsible for predetermination of the chemical compound and it's Atomic number.
The Quantum molecular structure Vibration blue print is a Wave carrying the so to speak DNA of the final organic compound produced in the formation and assembly of all atoms. The Quantum Wavelength vibration harmonic only allows the Spin, orbital alignment, gravity and antigravity effects to form in one exact Color.
Each Quantum wavelength is a building blocks of one "Pure chemical compound". Quantum Wavelength vibrations harmonics control all atomic alignment of atoms employing Wave harmonic orbital alignment vibration code is locked inside the Quantum Wavelength. The Quantum Wavelength is the genesis of life which contain all the information for the "Construct" to create the chemical compounds that can be found equally distributed across the Universe.
Ronald Nussbeck
Empirical evidence as provided by NASA scientists show photographic visual evidence of Positrons created in the upper atmosphere by lightening strikes but also confirmed by Fermi's Gamma-ray burst monitor, Fermi's detected the signal of positrons annihilating on the spacecraft, twice, some of the particles reflected off a magnetic mirror point and returned. It is also verified that the Positrons flowed up Earths electromagnetic field by Fermi, this alone proves Positrons are not gravitationally bound but the most abundant proof is in the instruments.
Reply | Report Abuse | Link to thisFermi uses two instruments covering the 20 MeV to >300 GeV energy range, the Large Area Telescope (LAT) has a large collecting area, an imaging capability over a large FOV, and the time resolution and low deadtime sufficient to study transient phenomena. The LAT also provides active background discrimination and rejection against the large fluxes of cosmic rays, earth albedo gamma rays, and trapped radiation that are encountered in orbit. The Fermi Gamma-ray Burst Monitor (GBM) provides the spectral and temporal context in the classical 10 keV to 25 MeV energy band for gamma-ray bursts (GRBs) observed by the LAT, detects and localizes bursts, and alerts the LAT that a burst is in progress. Fermi can autonomously alter its observing plan to observe strong GRBs during and after the low-energy gamma-ray emission, and provides rapid notification to the science community. Science must now come to ask where do Positrons go when released from the confines of the atoms grip and how many have accumilated? The answer is they follow a path along the originating Planets electromagnetic field until it ends at which point the Star or next dominant electromagnetic field becomes dominant, it flows away from the gravitational body as proven by Fermi. Once the Positron exits the Solar system the Positron takes the path of the Galaxy's Black Hole electromagnetic field. Because even a Black Holes gravitational force is in direct opposition to Positrons antigravity it Halo's around the Galaxy until the electromagnetic field of the Galaxy weakens or ends releasing the Positron. I have postulated that there is another electromagnetic field that the Positrons follow, the Universe creates a electromagnetic field which the Positrons follow. Using WMAP we find exactly what has been theorized, a coalescing of anti-matter at the edge of the Universe, the place where the Aurora shines and where Positrons collect.
Ronald Nussbeck
Unlike a stellar wind, the effects of gravitation are not distance limited, only diminished in accordance with the law of inverse squares. However, even the gravitational effects produced by the Milky Way's central black hole represent only a small fraction of the galaxy's total gravitational effects.
Reply | Report Abuse | Link to thisI suggest that that the specific flow velocity of the interstellar medium is locally, regionally and galactically determined local, regional and galactic mass distributions.
I suggest that the interstellar medium is itself rotating around the galactic center, and that shock waves have only been observed for giant stars that happen to have peculiar velocities in relation to the interstellar medium because most stars in the galactic disc do not have such peculiar relative velocities.
Please see, especially:
http://en.wikipedia.org/wiki/Heliopause#Cassini_results
Since photons are attracted by gravity, photons probably also have gravity. Therefore, photons between stars actually add gravity to the universe. Perhaps dark matter is an illusion that is simply due to the gravity of photons.
Reply | Report Abuse | Link to thisGravity of photons might also explain why the universe appears to be expanding. Gravity between photons lowers their energy as they travel great distances in space.
I'm just a pedestrian, but you seem to be juxtaposing cause and effect - in an interesting way.
Reply | Report Abuse | Link to thisIn simple relativistic terms, light is understood to respond to gravitational effects because gravitation curves the spacetime that light traverses. Light as a EM wave self-propagates through (expanding) spacetime, an effective vacuum, at the speed c precisely because it has no rest mass.
While gravitation is not completely understood, theories that presume that its effects are proportional to mass are (when applied correctly) have become generally established because they are highly successful.
I think the effect of gravitation (equivalent to velocity) on light could also be understood as gravitation contributing to its total (but not net) velocity by redirecting it.
Please see:
http://en.wikipedia.org/wiki/Photons#Experimental_checks_on_photon_mass
"Photons inside superconductors do develop a nonzero effective rest mass; as a result, electromagnetic forces become short-range inside superconductors" - in this case light does not propagate at the speed c.
If we assume that photons are actually dark matter then the dark matter emitted by the Sun is five million metric tons per second. This means that in the volume between the Sun and Pluto, the mass of dark matter, as photons, is about 2.5 billion metric tons. This is a very small amount. Therefore, it may be that the gravity that photons exert is directional. Perhaps photons have much more gravity as they approach a particle of matter, and perhaps photons have less gravity as they pass and continue into space away from the Sun. In other words, photons may exert much greater gravity as they approach and much less as they leave. This means that photons lose energy as they come towards us from the Sun although they gain energy from Earth as they approach Earth from the Sun.
Reply | Report Abuse | Link to thisIt seems that photons cannot leave a black hole, and photons fall into a black hole. If photons exert gravity on a black hole then they should be able to escape a black hole. But perhaps black holes cannot emit photons from their surfaces at all.
I think photons probably are dark matter. For example, when photons are absorbed they exert anti-gravity since photons do have radiation pressure. Radiation pressure is actually due to photon anti-gravity, since photons have no mass. On photon-absorption, photon-gravity-gain reappears as repulsion instead of attraction, which explains how a photon with zero mass can impart momentum to the Earth when sunlight hits the Earth and is absorbed.
Continuing with the topic of my last comment, dark matter, if it consists of photons, and if their apparent gravity is due to negative-radiation-pressure, will actually have apparent mass. For example, the apparent mass of five million metric tons per second (of photons coming from the Sun) is actually 150 trillion metric tons. This is the apparent dark matter mass between the Sun and the Earth, inside a sphere with that radius.
Reply | Report Abuse | Link to thisNew theories are awaited to explain the dark matter. I have a new theory. Can experts verify that? It can be found at http://akbmurugan.com/my_theories.
Reply | Report Abuse | Link to thisNew theories are awaited to explain the dark matter. I have a new theory. Can experts verify that? It can be found at http://akbmurugan.com/my_theories.
Reply | Report Abuse | Link to thisScientists will release a "White Paper" on Dark Matter as it relates to Positrons (antigravity particle) and there ability to reduce the effects of gravity March 1, 2013.
Reply | Report Abuse | Link to thisAs I wrote In Scientic America in June of 2011 Positrons make up Dark Matter, scientists now are ready to concede that Positrons are the leading candidate for dark matter.
Positrons are produced on Earth, yes antimatter is produced in mass quantity from Earths high altitude lighting storms, lighting striking hydrogen atoms release huge amounts of Positrons that escape Earth through it's electromagnet field. Positrons are antigravity particles that circle our Solar System, Galaxy and Universe along Magnetic fields and reduce the gradational forces of all objects by up to 6 times.
Ronald Nussbeck
Scientists have concluded the expansion of the Universe is because of an unknown force called Dark Energy or Dark Matter but there is now a name to replace these nick names, Positrons. Positrons will soon be found to be the force behind the acceleration of the Universe's expansion, it's pushing galaxy's away from each other with ever increasing speed. Positrons have since the very moment of creation accelerated the expansion with ever increasing velocity. Positrons created from Hydrogen atoms that have been split, on Earth this happens from lighting striking Hydrogen atoms in our upper atmosphere. The Positrons are antigravity that fly away from gravity bound matter following the electrometric field of the Earth, the Sun, Solar System, Galaxy. Electrons and Positrons race away from each other but distance does not diminish the push as the number of positrons rise the amount of electrons stay the same creating an imbalance in the force of gravity. This also would solve the question of why gravity is so weak when measured against the strength of the other 3 forces.
Reply | Report Abuse | Link to thisRonald Nussbeck