Simulating dark matter by assuming stable solution

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Discussion Overview

The discussion revolves around the exploration of dark matter models, particularly focusing on the concept of assuming stable solutions for the universe and how this might constrain various dark matter theories. Participants are interested in the implications of stability on models like Warm Dark Matter (WDM), Cold Dark Matter (CDM), and others, while also considering observational constraints and previous simulations.

Discussion Character

  • Exploratory
  • Debate/contested
  • Technical explanation

Main Points Raised

  • One participant inquires about research that constrains dark matter models by assuming a stable solution for the universe, expressing interest in how this might yield sensible constraints on dark matter properties.
  • Another participant asserts that there is no stable solution for the universe due to its expansion and out-of-equilibrium state.
  • A clarification is made regarding the term "stable solution," focusing on stability for galaxies over short time scales, suggesting that any solution can be stable temporarily.
  • Further discussion emphasizes the need for a clear definition of "short" time scales, as stability can vary significantly depending on the duration considered.
  • One participant expresses a lack of interest in solving the question themselves, indicating that they seek insights from other researchers rather than developing time scales and constraints independently.

Areas of Agreement / Disagreement

Participants exhibit disagreement regarding the existence of stable solutions in the universe, with some asserting that stability can be defined for short time scales while others argue that the universe's expansion prevents any stable solution from being valid in the long term. The discussion remains unresolved with competing views on the implications of stability in dark matter modeling.

Contextual Notes

The discussion highlights the ambiguity surrounding the definitions of stability and time scales, which may affect the interpretation of models and their constraints. There is also a mention of existing research on various dark matter models that may provide context for the ongoing inquiry.

ohannuks
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Hey,

I've a short question. Is there any research attempting to constrain models of dark matter by assuming stable solution for the universe? I'm interested in knowing whether this gives any sensible constraints on the dark matter models.

I'm still fairly new to studying dark matter but as I understand there are loads of different models floating around; Warm Dark Matter (WDM), Cold Dark Matter (CDM) (with and without collisions), self-annihilating dark matter, fuzzy dark matter (non-relativistic bose condensate), and so forth. The idea has been, as far as I understand, is to try to constrain the dark matter model to fit the observations, and to constrain the "Dark Matter particle" properties.

The researches I've read about have been done as follows (as far as I understand):
  1. Make an educated guess on the properties of dark matter while letting one or two variables regarding the 'dark matter particle' go unconstrained
  2. Run the simulation from initial stage to final stage (final stage usually being the observable universe)
  3. Analyze the result and compare with observations

My question is whether there are any attempts at doing the following in any shape or form (and I'd appreciate it if I could read about them):
  1. Make a model with as little constraints as possible
  2. Create an initial stage based on observations and corrections to the results of previous simulations (effectively this means creating the observable universe)
  3. Assume that the system is stable
  4. Constrain the model to only include the solutions that do not shake the stability
Thanks.
 
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Stable solution? There is no stable solution. The universe is expanding. It is out of equilibrium, and will remain out of equilibrium until there is nothing left but empty space.
 
I should clarify; I mean stable solution for galaxies on short time-scales and whichever structures remain stable if left alone (the bare-bone idea).

In short, I'd like to read about research with heavy emphasis on creating a "minimum constraint" model with constraints directly from observations (and/or previous simulations)

observations (and/or previous simulations): By this I mean that the starting point of the model is the expected solution.

Ps. Is there any way to edit the initial question afterwards? It would be helpful to correct it in case some people only read the original post.
 
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ohannuks said:
stable solution for galaxies on short time-scale

On a short enough time scale, any solution is stable, On a long enough time scale, virtually all are not. This condition has no meaning without a better definition of "short", in years,
 
Vanadium 50 said:
On a short enough time scale, any solution is stable, On a long enough time scale, virtually all are not. This condition has no meaning without a better definition of "short", in years,
One can construct a model which blows up after any finite time-scale (whether this is physical or not is another question).

I should clarify further; I am not interested in solving this question myself (that means I'm not interested in coming up with the time-scales and constraints from observations; this has already been researched by so many people before, see research on MSP, CCP, catch 22, MFP and dwarf spheroidal galaxies..) I'm interested in the thoughts of other researchers on the subject.
 
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