synthesizer.kernel_functions¶

A module defining SPH kernels integrated along the line-of-sight.

This module provides a class for calculating SPH kernels integrated along the line-of-sight. The kernels are used in smoothed particle hydrodynamics (SPH) simulations to compute the density of particles in a given volume. The kernels are defined as functions of the distance from the center of the kernel and are integrated along the line-of-sight to obtain the density distribution.

Available kernels include:

uniform
sph_anarchy
gadget_2
cubic
quintic

Example usage:

kernel = Kernel(name=”sph_anarchy”, binsize=10000) kernel_data = kernel.get_kernel()

Functions

synthesizer.kernel_functions.cubic(r)[source]¶

Calculate the cubic kernel.

Parameters:: r (float) – The distance from the center of the kernel.
Returns:: The value of the cubic kernel.
Return type:: float

synthesizer.kernel_functions.gadget_2(r)[source]¶

Calculate the Gadget-2 kernel.

Parameters:: r (float) – The distance from the center of the kernel.
Returns:: The value of the Gadget-2 kernel.
Return type:: float

synthesizer.kernel_functions.quintic(r)[source]¶

Calculate the quintic kernel.

Parameters:: r (float) – The distance from the center of the kernel.
Returns:: The value of the quintic kernel.
Return type:: float

synthesizer.kernel_functions.sph_anarchy(r)[source]¶

Calculate the SPH Anarchy kernel.

Parameters:: r (float) – The distance from the center of the kernel.
Returns:: The value of the SPH Anarchy kernel.
Return type:: float

synthesizer.kernel_functions.uniform(r)[source]¶

Calculate the uniform kernel.

Parameters:: r (float) – The distance from the center of the kernel.
Returns:: The value of the uniform kernel.
Return type:: float

Classes

class synthesizer.kernel_functions.Kernel(name='sph_anarchy', binsize=10000)[source]¶

A class describing a SPH kernel integrated along the line-of-sight.

Line of sight distance along a particle, l = 2*sqrt(h^2 + b^2), where h and b are the smoothing length and the impact parameter respectively. This needs to be weighted along with the kernel density function W(r), to calculate the los density. Integrated los density,

D = 2 * integral(W(r)dz) from 0 to sqrt(h^2-b^2),

where r = sqrt(z^2 + b^2), W(r) is in units of h^-3 and is a function of r and h. The parameters are normalized in terms of the smoothing length, helping us to create a look-up table for every impact parameter along the line-of-sight. Hence we substitute x = x/h and b = b/h.