Test set-up for full dark matter simulation

[ohannuks]

Hey,

I'm trying to look for a single test set-up for a dark matter-only simulation I and my friend are building. It's currently based on a particle-in-cell approach and we are calculating the Poisson equation and particle trajectories in a co-moving frame (so expansion of the Universe is taken into account).

However, it still lacks hydrodynamics and so I suppose we're neglecting baryonic physics.

Does anyone know of any good test cases for dark matter-only simulations to see if our simulation's predicting correct behaviour?

Since I'm new I'm sorry if I'm posting in the wrong place..

:)

 

[marcus]

Sounds interesting. I'm curious about specifics. Is this simulation to be limited to a small region? Or is it a simulation of dark matter on a very large scale?

What questions might you be trying to answer, using this simulation?

How far back in history do you go? Like, what redshift? what initial density of dark matter?

 

[Andrekosmos]

The hydrodynamics is important for the active liquid xenon to search for xenon nuclei that recoil in response to collisions caused by an impinging flux of dark matter particles (WIMPS). So your simulation can involve what we would expect from http://lz.lbl.gov/detector/

 

[mfb]

The hydrodynamics is important for the active liquid xenon to search for xenon nuclei that recoil in response to collisions caused by an impinging flux of dark matter particles (WIMPS). So your simulation can involve what we would expect from http://lz.lbl.gov/detector/

I don't think ohannuks plans to simulate a detector.

Hydrodynamics is used here for the motion of dark matter in the universe.

 

[ohannuks]

Hey all and thanks for all the replies.

We used the Uintah framework for doing our simulations. In the end, we decided to make DM-only simulation on local scale, simulating the formation of a dark matter halo and comparing its distribution with the Navarro–Frenk–White profile. The test set-up was fairly simple, we simply initialized it with random distribution. The project was mostly about learning the basics of DM simulations, and we decided not to include hydrodynamics into it. On one hand, it would be nice to have a working code made with a grid framework that boasts scaling up to the largest supercomputers but on the other hand there are already great, working simulation codes such as Gadget-2 and Enzo that do the same thing and more, even if their scaling capabilities are limited.

@marcus, Great to hear you're interested! We were interested in redshifts ~20, merely because most of the articles we read were interested in those redshifts.

@mfb From what I understand dark matter can be assumed to be collisionless, which is why the effect of hydrodynamics is often assumed negligible for dark matter, but not for baryonic matter.

We decided to have our project as a nice in-depth look into advanced numerical grid- and particle methods and an introduction to cosmological simulations (since neither of us are from a cosmology background). We also got immensely interested in other methods for local scales, such as simulating local dynamics via Boltzmann equation; from what I understand this is the next logical step for simulations.

Sorry for the late reply. I will reply a bit earlier next time.