The dark-matter tag has no wiki summary.
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What is the upper-limit on intrinsic heating due to dark matter?
Cold dark matter is thought to fill our galactic neighborhood with a density $\rho$ of about 0.3 GeV/cm${}^3$ and with a velocity $v$ of roughly 200 to 300 km/s. (The velocity dispersion is much ...
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3answers
607 views
Are modified theories of gravity credible?
I'm a statistician with a little training in physics and would just like to know the general consensus on a few things.
I'm reading a book by John Moffat which basically tries to state how GR makes ...
16
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3answers
717 views
How do we know Dark Matter isn't simply Neutrinos?
What evidence is there that dark matter isn't one of the known types of neutrinos?
If it were, how would this be measurable?
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2answers
656 views
Correlation between outstanding hints in experimental particle physics
The 115 GeV ATLAS Higgs with enhanced diphoton decays has gone away but there are several other recent tantalizing hints relevant for particle physics, namely
CoGeNT's 7-8 GeV dark matter particle ...
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6answers
835 views
Why isn't dark matter just matter?
There's more gravitational force in our galaxy (and others) than can be explained by counting stars. So why not lots of dark planetery systems (ie without stars) ? Why must we assume some undiscovered ...
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2answers
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Is there evidence of dark matter in our galaxy?
Is there evidence of dark matter in our galaxy?
How can we measure this, say, how many percent of the center of our galaxy is dark matter?
I did not find the answer in the question What's Dark ...
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2answers
249 views
Do we have an idea about the amount of matter in the universe?
Do we consider the amount of matter in the universe to be "infinite"? Or do we have an idea about "how much" there is?
9
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1answer
571 views
How do we know Dark Matter is non baryonic?
It seems widely stated, but not thoroughly explained, that Dark Matter is not normal matter as we understand it. Wikipedia states "Consistency with other observations indicates that the vast majority ...
9
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1answer
223 views
What dark matter can AMS currently find (or exclude)?
The rumor mill is running again, this time it's about the AMS experiment (Alpha Magnetic Spectrometer) that's going to make a major announcement soon.
I suppose they are looking for peaks in gamma ...
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4answers
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What makes the stars that are farther from the nucleus of the galaxy go faster than those in the middle?
It has no sense that stars that have a bigger radius and apparently less angular speed($\omega$) goes faster than the ones near the center.
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5answers
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How Does Dark Matter Form Lumps?
As far as we know, the particles of dark matter can interact with each other only by gravitation. No electromagnetics, no weak force, no strong force. So, let's suppose a local slight concentration ...
8
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1answer
177 views
Distribution of Dark Matter around galaxies
It is well-known that measurements of the velocity profile in galaxies are not compatible with Newtonian laws. A way to circumvent the problem is to assume that galaxies are surrounded by a spherical ...
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3answers
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What's dark matter and who discovered it?
I have heard about dark matter that's called the Master Of The Universe. What's this and is the dark matter the reason galaxies exist?
7
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2answers
491 views
Is dark matter repulsive to dark matter? Why?
I think I saw in a video that if dark matter wasn't repulsive to dark matter, it would have formed dense massive objects or even black holes which we should have detected.
So, could dark matter be ...
7
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1answer
286 views
What properties of Germanium make it suitable for Dark Matter detectors?
What properties of Germanium make it suitable for Dark Matter detectors?
I tried googling but there was too many results describing the use of Germanium Chrystals at low tempretures for Dark Matter ...
7
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2answers
235 views
Would dark matter absorb gravitational waves?
Would the vast and seemingly diffuse clouds of dark matter floating around our galaxy (and most others) absorb gravitational waves? Is this perhaps why we haven't detected any yet?
6
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3answers
800 views
Why can't dark matter be black holes?
Since 90 % of matter is what we cannot see, why can't it be black-holes from early on? Is is possible to figure out that there are no black holes in the line of sight of various stars/galaxies we ...
6
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4answers
356 views
How do we know that dark matter is dark?
How do we know that dark matter is dark, in the sense that it doesn't give out any light or absorb any? It is impossible for humans to be watching every single wavelength. For example, what about ...
6
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1answer
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Temperature of WIMPs
As a dark matter candidate, what should be the temperature and kinetic energy (or also the speed) of the WIMPs (weakly interacting massive particles) to agree with the observed distribution of dark ...
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4answers
307 views
Dark matter references
I've been looking for questions about dark matter, and I've read some very interesting answers. However, I desire too look into it deeply.
This is not actually a question. I'm asking the community ...
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2answers
229 views
Is dark matter really present around the sun?
Recently I read an article that there is dark matter around the sun but if it is so, than why can we see it clearly.
If it is called matter than it shall show some hindrance in radiation we receive ...
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3answers
79 views
Could dark energy be the effect of gravity at great distances?
This may be a silly question, but is it possible that dark energy and gravity are related to each other?
Space-time is deformed everywhere in space by objects with mass. The more massive the object, ...
5
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1answer
466 views
7 GeV dark matter particle: how particle accelerators missed it?
This posting is regarding the recent confirmation of the DAMA results that might be due to underlying differences in proton and neutron cross section with the dark matter particles, which reflect on ...
5
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2answers
102 views
following up dark matter accretion in supermassive black holes
A while ago, there was some conspicuous evidence that supermassive black holes didn't seem to be eating dark matter at the expected rate of 70%-30%, in fact, only 10% of the black hole mass increase ...
5
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1answer
210 views
Does dark matter have to be matter?
There is a very similar question to this one: Is dark matter really matter?. But the particular aspect I'm asking about seems not to be mentioned there. So, here we go:
Does dark matter have to exist ...
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4answers
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Is dark matter around the Milky Way spread in a spiral shape (or, in a different shape)?
Dark matter doesn't interact with electromagnetic radiation, but it, at least, participates in gravitational interactions as known from the discovery of dark matter. But does dark matter exist in a ...
4
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2answers
110 views
Can dark matter be relativistic dust?
As far as I know the mass of an observed object increases as it approaches the speed of light.
Is it possible that the excess mass called "dark matter" is due to relativistic dust?
Surely, stars ...
4
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2answers
320 views
How much light is there in space and how heavy is it?
Our night sky is filled with stars. On a dark night a significant fraction of the sky is light. This light, we are told, has been in transit for many millions of years. There must therefore be quite a ...
4
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2answers
308 views
Sparticles: Relationship to supersymmetry and dark matter?
I was attempting to read this paper after watching a show with Brian Greene. As I understand it, sparticles are a prediction of supersymetry, so I was wondering:
Wouldn't the discovery of ...
4
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2answers
238 views
Sterile Neutrinos as Dark Matter
There has been recent activity by astrophysicists to determine whether a fourth flavor of neutrino, a sterile neutrino, exists. It would likely be more massive than electron, muon or tau neutrinos. ...
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1answer
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3answers
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What current alternatives are there to the standard concordance model of cosmology?
The current "standard model" or concordance model of cosmology is Lambda CDM which includes late time acceleration due to a cosmological constant, cold dark matter as the missing matter component and ...
4
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1answer
154 views
How much does electromagnetic radiation contribute to dark matter?
EM radiation has a relativistic mass (see for instance,
Does a photon exert a gravitational pull?), and therefore exerts a gravitational pull.
Intuitively it makes sense to include EM radiation ...
4
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1answer
88 views
Experimental foundations of the “otherwise galaxies would not hold together” argument for dark matter
On the question of motivation and evidence for dark matter, there are some illuminating (so to speak) answers on this site. I'd like to understand in detail the foundations of one of the lines of ...
4
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2answers
321 views
What is currently incomplete in M-theory?
As it is, what is currently and seemingly incomplete in M-theory?
One example I can give is explaining dark matter proportions
and.. how do we perceive the world as 4-dimensional.
Thanks everyone.
4
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1answer
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Does the dark matter halo rotate with the galaxy?
If the dark matter halo is stationary related to the arms of the galaxy then tidal effects should slow the galaxy rotation.
If it rotates with the normal matter in the galaxy then shouldn't it ...
4
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1answer
106 views
Can dark matter and energy be formulated as local perturbations of the metric
Note, my formal physics education ended over ten years ago so I may be missing some obvious piece of understanding.
The relationship between space-time and matter/energy distribution is described by ...
4
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1answer
73 views
How the CMB anisotropy is linked to the existence of cold dark matter and dark energy?
After the data from the cosmic microwave background has been collected by WMAP or Planck, what types of analysis is needed to conduct in order to deduce the cold dark matter density and the ...
4
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1answer
165 views
Does conformal gravity explain the Bullet cluster lensing effects?
Conformal gravity is an "alternative" theory of gravity, where instead of using the Einstein-Hilbert action composed of the Ricci scalar, the square of the conformal Weyl tensor is used. It was ...
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1answer
88 views
Why doesn't the dark matter halo co-rotate with the luminous disk?
What keeps it from falling into the center if not angular momentum?
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2answers
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If dark matter is a new type of particle, what does that imply?
My understanding is that dark matter cannot be (or is at least highly unlikely to be) an exotic form of any known particle. On the other hand, articles about particle accelerators seem to say that the ...
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2answers
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How convincing is the evidence for dark matter annihilation at 130 GeV in the galactic center from the Fermi Satellite data?
I listened to Christoph Weniger present his results at SLAC today. See his paper is here: http://arxiv.org/abs/1204.2797 and also see a different analysis here: http://arxiv.org/abs/1205.1045. The ...
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1answer
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What happens when astronomical bodies made up of Dark Matter collapse or collide?
Does dark matter not produce heat or radiation after a collision etc?
Or, we detect radiations having no generators?
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2answers
496 views
Does Dark Matter interact with Higgs Field?
Dark matter does have gravitational mass as we know from its discovery. Does it have inertial mass?
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2answers
144 views
Dark matter: degrees of freedom
I'm afraid this question could sound a little too vague. I don't even know if dark matter (DM) can be genuinely described by quantum field theory, or if quantum field theory should be somehow ...
3
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4answers
197 views
Possibility for radiation in dark matter that is not interactive with regular matter?
Definition: Radiation in this case does not refer to electromagnetic radiation. It refers to any kind of emission of energy, even energy that does not interact with regular matter.
Just like dark ...
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2answers
65 views
Orbits within a $-\vec{r}$ field
Let's say that we have a cold dark matter theory, so we imagine weakly interacting particles. Now, let's say that one of those dark-matter particles has a rare interaction while traveling through the ...
3
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2answers
310 views
Is dark matter really matter?
Is dark matter really a form of matter? We know it has a gravitional attraction and we know that everything that has a gravitional force is made by matter. But maybe this is an exception?
And if ...
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2answers
101 views
Why is the dark matter density profile within the solar radius (and local density) uncertain?
It seems that we know the rotation curve inside the sun's galactic orbit fairly accurately. Then wouldn't we be able to just take the derivative* of this to get the DM density profile at smaller ...
3
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1answer
135 views
Difference between baryonic, inertial and gravitational mass? (and relation to dark matter)
Inertial mass: determined from Newton's f = ma
Gravitational mass: determined via Newton's law of gravity
Baryonic mass: sum of mass of all baryons.
Which ones ...
