Questions tagged [dark-matter]

Matter not observed directly but inferred to exist based upon its gravitational effects.

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1answer
382 views

Can we regard dark matter as a special fluid rather than individual particles?

If we assume that dark matter is an $N$-body system of sizeless and collisionless particles which only interact via newtonian gravity, do these huge quantity of particles manifest some collective ...
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235 views

Relation between dark matter and supermassive black holes located in the center of galaxies

This research (see press article and technical paper), conducted on 3000 elliptical galaxies (which are typically galaxy merger results), reports finding "distinct relationship between the mass of the ...
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Are black holes in a binary system with white holes, and are they both wormholes? [closed]

What is a black hole? The general explanation is that a black hole is small region in space with such strong gravitational effects that nothing can escape and even light is trapped inside of the event ...
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420 views

WIMP dark matter annihilation rate equation (approximation)?

WIMP is a possible dark matter candidates, which self-annihilates. What is the WIMP annihilation rate, as a function of density? Most sources state this scales as $\rho^2$, (density squared), but ...
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265 views

Shouldn't dark matter distort light and therefore be directly detectable?

It is an established fact that gravity bends space time and therefore distorts light. We know that Dark matter acts gravitationally. So, just for giggles, lets say I had a sphere of dark matter ...
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Dark Energy and Wormhole stability

Is it possible that the "negative energy" needed to create stable wormholes as theorized by Morris and Thorne (?) could be dark energy? Could this be the "exotic" negative energy matter referred to?
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2answers
161 views

Could black holes interact with dark matter at distances far greater than matter?

I watched this Nova episode on super massive black holes and learned that the speed at which the outer stars in a galaxy orbit correspond to the size of the black hole at the galaxy's center. They ...
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1answer
39 views

What is our confidence with respect to the critical density of the universe? [closed]

How can scientists speak confidently about the critical density of the universe while knowing the majority of matter and energy is foreign and not well understood. Shouldn't more knowledge about dark ...
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1answer
131 views

Evolution of dark matter and gas temperature

So I have recently watched a simulation of dark matter density and gas temperature evolution in a universe. However I couldn't find description of under what assumptions it was was made and what it is ...
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397 views

Why standard model particles cannot be dark matter particles

I'm interested if any of the particles in the standard model could be potential candidates for dark matter? I know that we do not see dark matter, therefore dark matter does not interact ...
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What does “fully depleted” mean?

In many papers/articles on CCDs, particularly those used for dark energy surveys and dark matter detection, the term "fully depleted CCD" is used. What does this mean? References: http://arxiv.org/...
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What is the analogous effect of cosmological redshift for particles with mass?

Due to the metric expansion of space, light emitted from earlier times in faraway parts of the universe and travels for a long time to reach us get progressively redshifted, decreasing the energy of ...
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Restrictions on theories which describe particle which is the dark matter candidate

Lets have theory which describes (cold) dark matter candidate. I know two cosmological (not astrophysical) restrictions for particle: its lifetime has to be larger than the lifetime of the Universe, ...
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Is Dark Matter accounted for in early universe inflationary models?

In the early universe there must have been an abundance of dark matter unless it formed by some unknown process later on. If it were present, is this significant and factored into our models?
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Is most of the matter in the observable universe within galaxies?

Do we know, either through observations or through theory driven computer simulations, the location of the majority of the visible matter in the observable universe? That is, is it located within ...
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1answer
95 views

Does this analogy with matter and energy hold? [duplicate]

Matter is to energy as dark matter is to dark energy. Is that statement correct? If not, is there any relationship, that we know of, between dark matter and dark energy? When I say there is an ...
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1answer
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What is the ratio of cosmic ray energy to dark matter energy in our solar system?

In any cubic meter of space in our solar system there is predicted to be some amount of dark matter. Also in a cubic meter of space is a known average amount of cosmic ray energy. What is the ratio of ...
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1answer
133 views

How dark matter makes ordinary matter far from the center of a disc galaxy rotate faster?

I was reading several questions on this subject, incluiding duplicates, and even received the very useful help of Kyle Oman in this question to understand the behavior and distribution of DM. But I'm ...
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793 views

Is there a possibility of anti-dark matter?

Based on Galactic Gamma Ray Emission My question is simply put. Although dark matter itself is almost a complete mystery, has anything been published which postulates the existence of anti-dark ...
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75 views

Dark matter configuration

We live in a 3D world comprised of 4 dimensions, if you include time. The unit of spacetime as we "see" it is the proton, comprising of 6 quarks, fermions. Hence since these quarks cannot occupy the ...
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112 views

Is Dark Energy and or Dark Matter directly proportional to EMR? [closed]

Is Dark Energy directly proportional to Electromagnetic radiation (EM radiation or EMR)?
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533 views

Density of dark matter along the galaxy [duplicate]

I was reading these 2 interesting articles about dark matter inside the solar system: Does Dark Matter affect the motion of the Solar System? The Incredible Dark Matter Mystery: Why Astronomers Say ...
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4answers
737 views

How can I add dark matter to my $N$-body simulation?

I've written a simple non-scientific N-body simulation for fun: http://magwo.github.io/fullofstars/ I expected to create something looking like spinning galaxies (there are two invisible very heavy ...
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1answer
85 views

What $f(R)$ models pass most of the known constraints? [closed]

In most papers and talks about $f(R)$ gravity authors repeatedly state that the model proposed by Starobinsky 2007 $$ f(R)=R+\lambda\,R_{0} \bigg[\bigg(1+\frac{R^{2}}{R_{0}^{2}}\bigg)^{-n}-1\bigg] $$...
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Where would dark matter be produced?

There are a zoo of dark matter candidates. Are there any candidates which could be produced in extreme conditions such as black holes/active galactic nuclei/pulsars? After reading an article on WIMPs ...
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Is Dark Matter expected to be equally distributed in our solar system?

If dark matter winds up being roughly equally distributed in our solar system would this mean it has no net gravitational influence? Furthermore, do we expect dark matter to be less dense out in ...
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1answer
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Dark Civilizations? [duplicate]

I just read that maybe the dark matter could have dark forces. Hence, I wonder: dark atoms, dark galaxies, dark intelligent beings. Basically a parallel, interpenetrating universe. Is this plausible?...
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1answer
356 views

Galaxy bias and baryon acoustic oscillations (BAO)

I have a doubt with the concept of galaxy bias and how it affects baryon acoustic oscillations, it is supposed to mean that by measuring the distribution of galaxies we are not measuring the actual ...
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Effect of dark matter on measuring our weight

We know that 95% of the matter in the universe, and all around us, and in our room is dark matter. Dark matter does interact with normal matter only through gravitation. So, does it have an effect on ...
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1answer
413 views

Did dark matter cause the formation of the Solar System?

This question is related to my previous question on Solar System Formation and is a pure thought experiment, with as few as possible assumptions made. From my previous question, I learned that stars ...
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1answer
298 views

Signs of supersymmetry and thus dark matter at CERN

The Large Hadron Collider at CERN has just re-started after a two year pause and is now running at unprecedented levels of 6.5 TeV, with collisions that will release up to 13.5 TeV. With this increase ...
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1answer
99 views

Does dark matter originate from matter falling into a black hole? [closed]

Is it possible that due to the fact that dark matter is clumped around black holes, that the dark matter used to be matter, fell into a black hole, and simply became dark? Furthermore, if the total "...
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211 views

Are there experiments taking place right now that might show evidence for or falsify dark energy or dark matter?

What experiments at quantum or cosmic level might provide the strongest supporting evidence for or, conversely, potential for falsifying, the existence of dark matter or dark energy?
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Implications of dark matter imprints on Cosmic Microwave Background Radiation?

Looking at this link, CMB Anisotropy, I have two questions regarding the possible creation and properties of dark matter: If dark matter has left it's imprint on the CMB, that to me, would imply ...
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584 views

Integrated Boltzmann equation for dark matter

In Dodelson's book, the equation for a scattering process $ a + b \Leftrightarrow c + d $ is given as \begin{align} a^{-3} \frac{\mathrm d (n_a a^3)}{\mathrm d t}&=-n^{\text{eq}}_a n^{\text{eq}}...
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6answers
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Can dark matter be converted to dark energy?

According to energy mass conversion law, mass can be converted to energy. So is it possible to convert dark matter into dark energy?
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1answer
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Could M-Theory explain dark matter as well as dark energy?

Is it possible that M-Theory provides a solution to the mystery of dark matter and dark energy? The idea of dark matter and dark energy is that there is some inexplicable source affecting our ...
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4answers
1k views

Why is the ratio dark matter / normal matter bigger today than in the past? Is it the dark matter that increased or the normal matter that decreased?

These two pie charts clearly show that the ratio dark matter / normal matter is bigger today than it was in the past. But why? How is it possible? And does it mean that the amount of dark matter ...
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Could there be a dark matter planet? [duplicate]

Since dark matter is gravitationally "charged", by which I mean it has mass and attracts things, could it bunch together to form a planet?
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1answer
181 views

Could dark matter be degenerate?

If dark matter were to be partly composed of fermions (such as hypothetical neutralinos), then could these particles be subject to degeneracy pressure if they were trapped in the potential well of a ...
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1answer
150 views

Dark energy and exotic states of space-time

So far as I know attempts to detect new particle that responsible for the nature of dark matter/energy are not successful. And there are reasonable explanation for this, like energy levels we can get ...
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1answer
99 views

Is there a real and relevant relationship between Big Bang and dark matter?

Since the postulate of dark matter is based on the unexpected rotational velocity around the centre of a spiral galaxy, then it can be presumed that the Big Bang Theory is not relevant to the search ...
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Why do planets moving around our Sun lead to how stars move around the centre of a spiral galaxy?

We know that the speed with which the planets go around our sun decreases as a function of the distance they are from the sun. Since stars are not planets, and presumably do not behave like planets, ...
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Dark matter clumping [duplicate]

How can dark matter particles (WIMP's) get ever more densely clumped during the evolution of the universe, as we see for example in the Millennium simulation, if they can't loose kinetic energy by ...
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1answer
148 views

Where would the dark matter particle fit inside a picture of the standard model of particle physics?

Where would the dark matter particle fit inside a picture of the standard model of particle physics? While I am particularly fond of the Sterile Neutrino, I have not been able to find any example of ...
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423 views

Where is all the Dark Matter? Theoretical Question

In my Physics Class we had to look into possible areas where Dark Matter could be "hiding." Such as Black Holes and so on. Dark matter really can be "seen" through its gravitational effects, and we ...
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is electromagnetic phenomena and particle behavior dependent on dark matter?

Dark matter permeates space and coalesce s in its own gravitational attraction. It neither absorbs or emits light or interacts well with baryonic matter. It deflects light on a path and is the sub ...
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1answer
62 views

Neutrinos born before inflation

What would happen, if there was (hypothetically, for any reason) a very large number of neutrinos+antineutrinos before the inflation period. They probably dont like to annihilate too much. I would ...
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What is the current state of axion research theoretically?

Is the problem (the strong CP problem) that is solved by axions still considered a really big problem, like the missing mass terms that could be solved by the Higgs mechanism? Or is it more a "problem"...
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Can Dark Matter just be clumps of Neutrons

I was wondering about Dark matter, and it occurred to me that why could it not be just nuclei of Neutrons with no electron cloud. Is it possible for such things to exists. Can Neutrons bond to one ...