Questions tagged [dark-matter]

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

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Gravitational non-linearities and Dark Matter/Energy

I had read Significance of Gravitational Nonlinearities on the Dynamics of Disk Galaxies (https://arxiv.org/abs/1909.00095), was wondering Is there good reason to think that gravitational non-...
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How the dark matter density parameter appears in Big Bang Nucleosynthesis (BBN)?

I know that it is possible to obtain the light element abundances ($^{4}\mathrm{He}, \mathrm D, ^{7}\mathrm{Li}$ etc.) and to determine the baryon-to-photon ratio $\eta$ from the total baryon ...
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Could the increasing expansion of the universe be proof of the multiverse? [on hold]

Einstein included a cosmological constant in his equations, this leads to the search for dark matter as I understand. Currently we fail to detect this dark matter. So what if it isn't there, but ...
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What might be the effect on galaxy rotation of a linearly and uniformly increasing galaxy mass (over time)? [closed]

In Cosmic clocks: a tight radius–velocity relationship for H i-selected galaxies, Meurer, Obreschkow, Wong, Zheng, Audcent-Ross and Hanish identify that galaxies behave as clocks, rotating once a Gyr ...
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Dark Matter and Equivalence Principle

Dark Matter effects show up in galaxies. Why isn't it considered as a violation of equivalence principle instead of assuming all these extra non-interacting particles as gravitational mass and ...
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Would dark matter (as a BEC) be captured by Black Holes, Neutron Stars, etc?

Suppose that dark matter is in the form of a Bose-Einstein Condensate, with a DeBroglie wavelength of ~10,000 LY. (There are some axion models of DM where the axions are in a BEC.) In this model, the ...
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Where can I find the star distribution data of our galaxy?

I am doing some research on dark matter and for that I need data of star distribution in our Galaxy. Is there any mathematical law that predicts the distribution pattern of stars in our Galaxy?
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Absorption of dark matter by black holes

Our Universe consists of about 22% Dark Matter (DM). Such matter is the main stuff of galaxies. Also, Black Holes (BH) live in galaxies. We know that DM is subject to gravitational interaction. So, ...
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Is dark matter inside galaxies different from dark matter in intergalactic space?

I just read a text about astronomy and when talking about dark matter the author says: [...], the dark matter responsible for the orbits of the stars in the Milky Way is probably different from the ...
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Could dark matter actually be matter which resides in a different spatial dimension? [closed]

I have at best a rudimentary understanding of the math in this side of physics, so bear with me. I am also aware of this question, but it was asked and answered 4 years ago and I don't want to ...
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Dark matter in the time window between freeze-out and kinetic decoupling

Background After the freeze-out, when all annihilations have stopped, the abundance ($Y=\frac{n}{s}$) of thermal dark matter species no longer changes with time. However, it is still kept in kinetic ...
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Does $\Lambda$CDM include inflation?

$\Lambda$CDM obviously includes dark energy (the $\Lambda$) as well as cold dark matter (CDM). Does it also include cosmic inflation? I've not seen a clear answer to this. Wikipedia's article on ...
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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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Can dark matter explain the unusual orbit of transnettunian objects? [closed]

While we are struggling to find an hypothetical planet 9 to explain the unusual orbit of transnettunian objects, I was wondering if it could be just dark matter. We know that the universe is mostly ...
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What crystals are being used in this project to detect dark matter?

I recently read an article about "groundbreaking Australian research in the hunt for dark matter", in which it said: We use highly purified crystals to detect dark matter. These crystals react when ...
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Sterile neutrinos findings

There is a relatively new paper https://arxiv.org/abs/1805.12028 of MiniBooNE on measurements of neutrino oscillations that can only be explained by the postulate of a sterile neutrino. I also read ...
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Why does nobody ever consider the possibility that the universe is not smooth?

Disclaimer: I'm not an astronomer, physicist, mathematician, etc. so this is a question from a complete newbie. One of the greatest mysteries of our age is "where is the dark matter?" The universe ...
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Could quasars produce elements heavier than oxygen?

I have read that supernovae are the main producers of elements heavier than oxygen. I just wonder whether quasars, which have been around a long time just like supernovae have, could have had a ...
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Elastic scattering between particles and forces

If a WIMP interacts elastically with a nucleus, for which force they interact? Weak force? The same for neutrons, it interacts via strong force? The only elastic scattering i know is the Rutherford ...
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How to calculate spin-dependent and spin independent scattering cross sections for different elements inside stars?

To calculate capture-rate of dark matter particles by stars, we need to calculate spin-dependent and spin-independent scattering cross sections for different elements inside stars. How it is ...
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Can dark matter actually be gravitational radiation?

It seems to exist like only space distortion, and it seems to move just like radiation (specially when galaxy clusters collide, dark matter goes trough unaffected just like some type of radiation). ...
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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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Formula for the bias of galaxies

From the article "Large-Scale Galaxy Bias", I try to deduce the equation that my teacher told me which links 2 quantities: the global number density of galaxies the local number density of galaxies ...
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What is phantom matter and how is it different from dark matter?

What is phantom matter and how is it different from dark matter? I have googled the term "Phantom Matter" and the results were mostly research papers which assume that the readers already know the ...
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Gravity as a repulsive force

As we know that universe is expanding, why can't we think the gravitational force as repulsive in nature in the realms of dark matter and dark energy?
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Primordial dark matter synthesis

In standard cosmology, there is a general picture of: Primordial nucleosynthesis, i.e., when and how, nuclei or elements were formed. It is not quite tested, but it is more or less known where it ...
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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 ...
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How do you distinguish between missing momentum from a neutrino and from dark matter?

I thought googling this would give me an answer quite quickly, but actually couldn't find much, so maybe it's a silly question. But I read that dark matter searches rely on measuring missing momentum ...
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What is the mass/cross section of Dark Matter candidates?

I understand that experiments at LUX, XENON and LHC have eliminated many of the predicted masses for candidates for Dark Matter. Does anyone know what the current lowest possible mass is that hasn't ...
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What proof do we have that dark matter is matter? [duplicate]

The Dark matter page on CERN's official website describes dark matter as if it were regular matter just with some mysterious properties. This was a surprise to me because every time someone mentions ...
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Exclusion limits on particle dark matter

I'm trying to make sense of how the upper limits of the cross-section of particle dark matter (WIMPs) are computed, like in the figure below. This is taken from an article on dark matter searches. ...
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Dark matter pressure

Dark matter is suppose to form large halos of unknown yet type of particle with a specific density density profile. Does the dark matter halo can be viewed as a fluid of particles with density and non-...
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Generally how much faster are stars on the outskirts of galaxies orbiting than they should be?

This assumes there is no mysterious matter causing the extra speed. Are they orbiting say 10% faster than expected etc?
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Dark Matter Stars Triggering Nebula Collapse

I'm interested in theories of dark matter where dark matter is an equivalent copy (or copies) of ordinary matter. Each equivalent sector is hidden from the others would see the others as 'dark' and ...
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How are the dark matter (DM) thermalization rates derived in singlet DM model?

This well-cited paper talks about a minimal renormalizable extension to the Standard Model (SM) to incorporate particle dark matter (DM) into it by adding a real scalar field $S$ which (unlike the ...
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Demonstration about large-scale bias of galaxies

From this article : https://arxiv.org/pdf/1611.09787.pdf , I try to deduce the equation that my teacher told me which links 3 quantities : 1) the global number density of galaxies 2) the local ...
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How does the cosmological constant dominate cold matter perturbations?

I have been studying inhomogeneous universe in physical cosmology, whereupon I arrive at cold matter perturbations which are dominated by various background fluids. I understood the solutions for the ...
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Spiral galaxy stability

Is there a limit of baryonic masses $M_{B}$ ($M_{B}=M_{\star}+M_{g}$), beyond which a spiral galaxy is no longer rotationally supported? Like for example: Could spiral galaxies of baryonic masses $M_{...
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Dark Matter vs Modified Gravity

Why do cosmologists and astrophysicists assume that the reason for the higher velocities of outer stars in galaxies is due to matter at all? The name dark matter seems misleading. Couldn't gravity ...
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Justification for new theories of Particle Physics and General Relativity

In reference to arxiv:1212.4893v3 and arxiv:1206.5078v2 papers of Ma and Wang, they have proposed new theories in particle physics, the weakton model where quarks and leptons are formed using these ...
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Why is the distribution of dark matter in a Galaxy different from the distribution of normal matter?

The dynamics of a galaxy are driven by gravity. And dark matter experiences the same gravitational forces as normal matter. The effects of other forces are very small in comparison. So why is the ...
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When galaxies collide, what happens to dark vs. light matter?

I have read that galactic collisions have been used as evidence demonstrating the effects of dark matter. In particular, that luminous matter slows down and interacts while dark matter shoots through, ...
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Dark matter composition [closed]

I assume that dark matter is made of heavy neutrinos.But wouldnt they be converted into neutrinos with less mass throygh weak interaction?So dark matter isnt made of neutrinos.I think there is truly ...
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Could dark matter be curved pockets of spacetime left over from the big bang?

My understanding of general relativity is that gravitation is equivalent to spacetime curvature and is proportional relative to localized mass. Traditionally, we conceptualize that massive things ...
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Dark Matter Wave Particle Duality

CERN is looking for dark photons, and they are seeking to look for interactions with the Higgs boson with the dark photon.See link here. So in other words a dark photon - a mediator for dark matter is ...
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How well supported by observations is the hypothesis that concentrations of dark matter are essential to galaxy formation?

Much work regarding the formation and early evolution of galaxies seems to assume that galaxies form based on clumps dark matter. The following observations indicate that some galaxies started with ...
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Dark matter and supersymmetric particles

Is there a possibility to consider supersymmetric particles of fermions and bosons as the unknown dark matter?
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Why physical / cosmological models that have been falsified weren't abandoned? [closed]

Before anything, I'd like to say that I'm a layman (non physicist) and english is not my main language; I apologize if my choice of words make me sound rude / arrogant, that is not my intent. I often ...
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Dark Matter search, why DAMA collaboration does not publish $S_0$?

Results from recent experiments are starting to come in, mostly in the direction of not confirming the annual modulation measuremements published by the DAMA/Libra collaboration. In the search for ...
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How do they know the numbers of the energy pie chart of the universe?

They say that the total energy of the universe consists of 4.9\% ordinary matter, 26.8\% dark matter and 68.3\% dark energy. I hear this pie part in virtually every lecture in cosmology. How do we ...