Questions tagged [dark-matter]
Matter not observed directly but inferred to exist based upon its gravitational effects.
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Readings on Dark Matter [duplicate]
I am looking for introductions and reviews (papers or books) on the possible observation and the nature of dark matter. This book seems to be a good start, but I would be grateful for any other ...
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Can photon be said to warp time only and not space? Can SR be modelled like GR, considering warping of temporal dimension only? [closed]
If we try to get closer and closer to a photon (i.e. get closer to speed of light), time slows down in a fashion similar to when we get closer and closer to a massive object. Are these two things ...
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What are the decay modes of a massive photon?
I need to find the possible decay modes of a massive photon (it's actually a dark photon but is being treated as a photon with rest mass that couples the same was to SM particles as a photon would) It ...
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Dark matter and gravitation
Dark matter does not interact with the electromagnetic force, however does interact with the gravitational force. Do we know if there are any big ‘clumps’ (like a star) of dark matter? If they exist (...
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Need help in deriving Boltzmann Equation for $3\to3$ scattering
This is the first time I am posting a question here, so please forgive me if I make any mistake. I am trying to derive the Boltzmann Equation for $3\to3$ scattering, which means there are 3 particles ...
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Could cosmological cold dark matter be a neutrino condensate?
What is wrong with the following?
Neutrinos are dark matter.
A neutrino condensate would be cold. (Often, neutrinos are dismissed
as being automatically hot dark matter.)
Cold neutrinos could be ...
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Cold neutrinos - how are they distributed?
Cold or slow neutrinos have non-relativistic velocities and hence very low energies. That makes them very difficult to detect. Answers to Where are all the slow neutrinos? make it clear that they are ...
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2answers
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Dark matter and velocity [duplicate]
We know that as the speed of an object increases, so does its relativistic mass.
But can it be said that dark matter may be due to the increasing relativistic mass of nebulae, stars, galaxies, etc. ...
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Cosmological consequences of the mass-energy content of gravitational waves
This paper published in 1969 indicates that a majority of the mass-energy of the universe may be contained in gravitational waves:
"Turning next to phenomena on a galactic scale, we find it ...
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Rotational velocity due to Dark matter
I was wondering if we can predict the rotational velocity due to dark matter in this way:
Consider that we theoretically derived the rotational velocity of a galaxy ($v_{the}$). Then from experiment ...
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If the Holdom Force Exists what would be the spin of the force carrier of the Holdom Force?
I read about Mirror Matter.
Mirror Matter, if it exists, would be similar to ordinary matter, but with the chirality of some of the mirror particles being reversed. If mirror matter exists then there ...
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What are ordinary mass-terms (of neutrinos)?
When reading the introduction to Sterile neutrino hot, warm, and cold dark matter I came across the following definition of sterile neutrinos:
We can define sterile neutrinos generically as spin-$\...
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Is It Possible Right Handed Neutrinos Are Dark Matter?
Disclaimer: I am not a physics expert, just a teen with an interest.
I was watching a SciShow video, and they were talking about left-handed and right-handed neutrinos. The idea is that right-handed ...
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Are ultra-cold neutrinos an option for cold dark matter? [duplicate]
Nobody hass seen cold dark matter. Are ultra-cold (non-relativistic) neutrinos, below 1 fK (femtokelvin), an option for dark matter?
This is a question about normal neutrinos - electron neutrinos and ...
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1answer
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Why is Fuzzy Dark Matter Cold?
Fuzzy dark matter (FDM) has a typical mass of $10^{-22}$ eV. With such a low mass, why is it typically assumed to be cold? That is, what keeps the FDM non-relativistic. With such a low mass, wouldn't ...
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Why is dark matter and dark energy needed to explain why there's more and less gravity respectively than there should be? [closed]
Why is dark matter needed to account for that there's more gravity than there should be, and dark energy for that there's less gravity than there should be?
Obviously that can't be correct, but I'm ...
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1answer
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Do dark matter and dark energy have different physical laws from ordinary matter and energy? [closed]
What are dark matter and dark energy?
Do dark matter and dark energy have different physical laws from ordinary matter and energy?
Can string theory explain their mechanisms?
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Dark Matter Abundance and Being a Cold Relic
I was reading Longair its stated that,
"An important conclusion was that, if dark matter particles were as common as neutrinos and photons,their rest mass energies could not be much greater than $...
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Unstable Dark Matter
Dark matter is generally considered to be stable or at least long-lived (age of the universe) and I understand that is necessary to have such abundance today. My questions are 3:
Is it 100% necessary ...
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Is dark matter paramagnetic/diamagnetic?
From my understanding, constrains on the interaction of dark matter with electromagnetic fields comes from the lack of scattering/absorption/emission of light.
But, do we know anything of its DC ...
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Are neutrinos and sterile neutrinos both dark matter candidates?
Are both neutrinos and sterile neutrinos candidates for dark matter?
In particular, why would "standard" neutrinos be a candidate for dark matter, since they interact with matter?
Why would ...
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What is the gas distribution in galaxies?
I'm fitting a number of galaxy rotation curves, and I need the density distributions of stars, gas, and DM. I know that the baryonic disk densities fall off exponentially (the characteristic radii can ...
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How are neutrinos massless? Could they or at least some of their forms be a potential candidate for Dark matter? [duplicate]
I am particularly new to this subject. Can neutrino physics be understood by a 10th grade?
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What do we know about the features of Dark Matter? [closed]
In 2020, how much information have we got about this matter? I'm just curious.
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What is the possible relevance of $R$-parity to dark matter?
So say if $R$-parity is preserved, then whatever particle (if we assume its a particle) the dark matter consists of, only interacting with the weak nuclear force and gravitational, then wouldn't this ...
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What is the meaning of a number changing process?
On my lecturer's notes on Dark Matter I am told:
"It is customary to define densities normalised by the time dependent volume $V (t) = a(t)^3$. The reason for this is that, in the absence of number ...
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Supersymmetry and Elko spinors
Now, very popular subject is Elko spinors.
Is it possible to construct supersymmetric theory with
Elko spinors as parameters of susy transformations?
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How is Einstein-Bose condensation supposed to stabilize d*(2380)?
A recent paper suggests a new dark matter candidate: Einstein-Bose condensates of the hexaquark/dibaryon d*(2380) ($uuuddd$). The nice thing about this theory is that it does not require any new ...
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If the distribution of dark matter is not uniform, why it is not attracted towards center of galaxies?
The dark matter hypothesis was formed due to difference in theoretical and observed speed of the outer parts of galaxies. Therefore, there is more dark matter in the outer parts of the galaxy than in ...
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How do I decompose my overall rotation curve for M31 into a rotation curve for the disk and halo?
How do I decompose my grand rotation curve into rotation curves for the disk and halo, like the image below?
The picture is from this link pages.pomona.edu/~tmoore/RotCurve
The data points are ...
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1answer
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What methods can I use to determine the total mass of M31 using rotation curve data (galactocentric radius and rotational velocities)?
I've used M(r) = RV^2/G to find the enclosed mass within the orbit of a target body in M31, but I want to use other methods to derive the total mass of the galaxy, including the mass of dark matter ...
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Indications on the axion symmetry breaking scale
The production of cold dark matter axions can be provided for by multiple mechanisms which in turn depend on whether the breaking of the $U(1)_{pq}$ symmetry occurs before or after the inflationary ...
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Expansion of the relation between the cosmological growth factor and scale factor
Hello i'm studying large scale structure of the Universe (in $\Lambda$CDM Universe) using as time the growth factor defined by
$$ \ddot{D}+2H\dot{D}-4\pi G\bar{\rho}_{DM}D=0$$
in my equations i have ...
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How to acquire Dark Matter? [closed]
I want to acquire some Dark Matter as is mentioned in this paper and I have two questions:
Is it possible to use helium balloon to reach to the Dark-Matter-sphere?
What type of ceramic or other ...
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Thermalization of BEC dark matter
In the context of BEC/superfluid dark matter, one of the important requirements is that - within galaxies - dark matter thermalizes [1]. Axions are appropriate in this regieme, as their self-...
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Questions about Dark Matter and Galactic Rotation
First, does the dark matter halo and galactic rotation of a galaxy depend on it's size? So bigger galaxies, bigger dark matter halo.
Secondly, is the amount of dark matter for a galaxy universal? So ...
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Introduction article/book to Lambda cdm Model
After reading Spacetime and Geometry of Caroll, I would like to understand better cosmology: in particular the $\Lambda$CDM model which is referred to as
"the standard model of Big Bang cosmology ...
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Is momentum conserved when dark matter falls into a black hole?
Since dark matter does not interact with any other forces (unless you consider the gravitational force), I would like to know what happens to the momentum of the dark matter when falling into a black ...
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What is dark parity?
What is the physical significance of the odd dark parity and even dark parity? Does it mean if a particle has odd dark parity then it is not a dark matter candidate?
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What is the mathematical expression of the Lambda-CDM model?
The conceptual meaning of this model is clear to me. But where can I find the actual mathematical model?
The Wikipedia page says "The simple ΛCDM model is based on six parameters". Six parameter ...
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Why couldn’t dark matter be from advanced technologies? [closed]
(Coming from a layman)
Why couldn’t dark matter be the consequence of advanced technology?
For many reasons I can imagine that the game theory for intelligent life is to eventually hide/ camouflage ...
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Does the no-hair theorem imply that dark matter cannot have any “charge”?
By "charge" I mean some kind of unique conserved property, similar to electric charge, color charge, baryon number, etc.
The no-hair theorem states that black holes can only have three macroscopic ...
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What does. DM- nu, sigma = 10^-33 m_DM GeV^-1 cm^2. mean?
I tried posting a screenshot above......
On Ethan Siegel's blog over at Forbes, he has repeatedly posted a graphic showing possible 'new physics' that could explain why the Planck satellite ...
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1answer
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Is there any evidence that dark matter interacts with ordinary matter non-gravitationally?
As far as I understand it, dark matter direct detection experiments are based on the idea that dark matter interacts with ordinary matter, it just has a very small cross-section. So far, there's been ...
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Can one galaxy have a higher dark matter ratio than another?
Dark matter do not interact with ordinary matter and light, it has mass and is affected by gravity. If the distribution of dark matter and ordinary matter is evenly spread at the early universe then I ...
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Can mass-dimension-one fermion be a dark matter candidate?
There is a growing body of literature on the ELKO spinors (see references here), which are alleged to be mass dimension one fermions and can be a dark matter candidate.
But is the ELKO spinor a red ...
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Dark matter without dark matter - review of suggested theories?
Is there any listing, directory, website or other central resource for suggestions that attempt to explain dark-matter-like behaviour without particulate matter being involved?
There's MOND, and ...
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Dark matter as an emergent phenomenon
Dark matter is invoked as a solution to anomalies in galactic rotation curves, galaxy motions in clusters, and gravitational lensing (please mention other evidence for dark matter that is relevant to ...
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Non-flat Galaxy rotation curves?
The galaxy rotation curve is stated as being constant, hinting towards the presence of dark matter. But few galaxy rotation curves are not constant but it keeps rising (an example shown in image), can ...
