Questions tagged [dark-matter]
Questions about astrophysical observations, experimental searches, and theoretical models related to dark matter and its quanta.
953 questions
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Consistency of a khronon EFT with a scalar medium metric 𝑑 𝑠 2 = − 𝜌 2 𝑑 𝑡 2 + 𝜌 − 2 𝑑 𝑥 2 ds 2 =−ρ 2 dt 2 +ρ −2 dx 2 [closed]
I am studying a theoretical model where gravity emerges from a scalar “clock-rate” field
ρ=(−X)−1/2,X=gμν∂μϕ∂νϕ,
with the metric written in unitary gauge as; ρ=(−X)−1/2,X=gμν∂μϕ∂νϕ,
The scalar ...
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In deriving the cosmological constant, and/or predicting dark energy/matter, how can we take d(area) or d(density) wrt $t$ when $t$ is not the same?
Using the fluid equation analogy for the energy density and area of the universe is suspicious. In the case of the fluid equation, it is assumed that time is the same axis for the entire problem. In ...
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Could Dark Matter be normal atoms that dont react with electromagnetism? [duplicate]
As if all their charges are perfectly cancelled out and light just passes right through without amplifying or cancelling out anything. Basically immune against ionization. How such a mechanism could ...
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Why is light more observed than darkness? [closed]
In terms of studying, researching, and scientific method light has been studied more than dark. Nasa says dark matter is the invisible glue that holds the universe together. This mysterious material ...
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Effective energy density of the gravitational field in General Relativity?
Within General Relativity, is there a well-defined or widely used formalism in which contributions from the gravitational field itself can be treated as an effective energy density on large (galactic ...
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Can stochastic halo non-equilibrium within ΛCDM produce a scale-dependent suppression of matter fluctuation amplitude $σ_₈$?
In the context of ΛCDM large-scale structure modeling, halo populations are typically treated as dynamically relaxed on average, with deviations absorbed into phenomenological fits of the halo mass ...
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Explain the phrase "to find dark matter in the sieve"
I need to translate an article: https://arxiv.org/abs/2501.06487.
In this document on page 8 there's a phrase:
"Authors argued that since any viable metric theory of gravity finds dark matter in ...
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Explain ultrarelativistic freezeout
Ultrarelativistic freezeout during inflation has been suggested as the primary source of dark matter in the universe. What does this imply as to the mass limits of DM?
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Is it feasible that multiple constituents of dark matter exist?
Having recently listened to a talk about experiments to find SUSY, one comment that stuck with me was that SUSY was originally postulated to solve a different problem/question in physics, and that it ...
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Is it statistically likely that a single black hole made of dark matter exists in the observable universe?
This popular article considers the question whether dark matter could be concentrated with a high enough local density to collapse into a black hole. It confidently concludes that the answer is "...
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Dark matter's gravity effect on a galaxy
In a galaxy if the vast majority of the dark matter halo is outside the visible normal matter, how does it pull that normal matter in and allow it to spin faster than it would if there was no dark ...
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Can dark matter interactions create detectable shockwaves in galaxy clusters?
Suppose dark matter has weak but non-negligible self-interactions. Could colliding clusters generate pressure-like shocks in the dark sector? If so, how would these affect gravitational lensing? I'd ...
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Is there an experiment (or a bunch of experiments) that would disprove particle dark matter?
Particle dark matter is a hypothetical substance that is posited to explain the observed stronger acceleration of the stars in galaxies than visible matter could account for. It means adding so-far-...
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Have galaxies had enough time to reach rotational equilibrium? [closed]
Current cosmology explains the anomalous galactic rotation curves by introducing dark matter—an unseen mass that adds gravitational pull, because stars orbit the galactic center faster than expected ...
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If dark matter and dark energy make up most of the universe, why haven’t we been able to detect them directly yet?
If dark matter and dark energy make up most of the universe, why haven’t we been able to detect them directly yet? And what does detecting "directly" even mean?