Add min smoothing length vs. redshift plot and update min smoothing length histrogram plot

[EvgeniiChaikin]

Two changes in this update

• Update the gas-particle minimal smoothing-length histogram by normalizing hmin_gas by gravitational softening at the corresponding redshift. I.e. before the update, hmin_gas would be plotted but now hmin_gas / \varepsilon_soft is plotted.

• Add a plot showing gas-particle minimal smoothing-length vs. redshift at which it as reached, plotted as a 2D histogram.

Here are the examples of the updated plot and the new plot

[EvgeniiChaikin]

@MatthieuSchaller, Joop just asked me to also add a curve indicating the redshift evolution of the softening. This is done in the most recent commit.

The new plot will look as follows

[MatthieuSchaller]

what is e_soft,min ?

[EvgeniiChaikin]

The minimum softening (the minimum between the comoving softening and the maximum physical softening).

Since you asked this, I am anticipating that it was not clear, so I should probably just write e_soft instead of e_soft,min.

[MatthieuSchaller]

Is the ratio then exactly 10^-4 ? seems weird to me.

[EvgeniiChaikin]

Now I do not understand.

If h_min is set to 1e-4 in the parameter file (https://gitlab.cosma.dur.ac.uk/EAGLE/swift-colibre/-/blob/master/examples/parameter_example.yml#L42), then we should see here a line at 1e-4, no?

[EvgeniiChaikin]

Because in the parameter file, we specify h_min relative to softening.

[MatthieuSchaller]

we specify e_plummer in the parameter file. That means the softening starts at 3 e_plummer. We then use H = h_min_ratio 3 e_Plummer. That then leads to h = h_min_ratio 3 * e_Plummer / kernel_gamma.

[EvgeniiChaikin]

Ah, I see what you mean now! Sorry for the confusion!

The script correctly applies the factor of 3 and kernel_gamma correction (https://github.com/SWIFTSIM/pipeline-configs/pull/256/files#diff-80007c0d55552991c352811da2c9f718499b849442d3c35e21641247c4c6891fR63) However, the axis does not say it.

What we plot is smoothing length * kernel_gamma / (3 * e_Plummer). This is why the line indicating the h_min ratio is exactly at 1e-4.

I purposely did not include kernel_gamma and 3 in the label of the X-axis because I didn't want to over-complicate the definition.

Do you think it would be better to change the axis label to something like h_min / (3 e_Plummer / kernel_gamma), or just add this extra information to the caption?

[MatthieuSchaller]

As long as the calculation is correct then it's ok like this.

[EvgeniiChaikin]

I extended the caption. It now says that both the factor of 3 and gamma_kernel are taken into account.

[MatthieuSchaller]

Yes, looks good.