csiborgtools/notebooks/field_velocity_fof_sph.ipynb

Tests of velocities of haloes in CSiBORG¶

In [1]:

import numpy as np
import matplotlib.pyplot as plt
import csiborgtools

%matplotlib inline
%load_ext autoreload
%autoreload 2

FoF vs SPH velocity¶

In [3]:

kind = "main"
nsnap = 99
nsim = 17417

field_reader = csiborgtools.read.CSiBORG2Field(nsim, kind)
catalogue = csiborgtools.read.CSiBORG2Catalogue(nsim, nsnap, kind)
boxsize = csiborgtools.simname2boxsize("csiborg2_main")

In [9]:

velocity_field = field_reader.velocity_field("SPH", 1024)

In [6]:

pos = catalogue["cartesian_pos"] / boxsize
vel = catalogue["cartesian_vel"]
mass = catalogue["totmass"]

spherical_pos = catalogue["spherical_pos"]
RA = np.deg2rad(spherical_pos[:, 1])
dec = np.deg2rad(spherical_pos[:, 2])

def project_radial(vx, vy, vz, RA, dec):
    vr = vx * np.cos(dec) * np.cos(RA) + vy * np.cos(dec) * np.sin(RA) + vz * np.sin(dec)
    return vr

In [36]:

vx, vy, vz = csiborgtools.field.evaluate_cartesian_cic(velocity_field[0], velocity_field[1], velocity_field[2], pos=pos)

In [43]:

fig, axs = plt.subplots(1, 4, figsize=(15, 4))

axs[0].hexbin(vel[:, 0], vx, gridsize=50, bins="log", mincnt=1)
axs[0].set_xlabel(r"FoF $v_x$")
axs[0].set_ylabel(r"SPH $v_x$")

axs[1].hexbin(vel[:, 1], vy, gridsize=50, bins="log", mincnt=1)
axs[1].set_xlabel(r"FoF $v_y$")
axs[1].set_ylabel(r"SPH $v_y$")

axs[2].hexbin(vel[:, 2], vz, gridsize=50, bins="log", mincnt=1)
axs[2].set_xlabel(r"FoF $v_z$")
axs[2].set_ylabel(r"SPH $v_z$")


vr_fof = project_radial(vel[:, 0], vel[:, 1], vel[:, 2], RA, dec)
vr_sph = project_radial(vx, vy, vz, RA, dec)
axs[3].hexbin(vr_fof, vr_sph, gridsize=50, bins="log", mincnt=1)
axs[3].set_xlabel(r"FoF $v_r$")
axs[3].set_ylabel(r"SPH $v_r$")

for i in range(4):
    axs[i].axline([0, 0], [1, 1], color="red", ls="--")

fig.tight_layout()
fig.savefig("../plots/velocity_comparison.png")
fig.show()

Correlation between the peculiar velocity and total mass¶

In [27]:

from scipy.stats import spearmanr

kind = "main"
nsnap = 99
nsim = 17417

catalogue = csiborgtools.read.CSiBORG2Catalogue(nsim, nsnap, kind)

vel = catalogue["cartesian_vel"]
mass = catalogue["totmass"]
velmag = np.linalg.norm(vel, axis=1)

print(spearmanr(mass, velmag))

SignificanceResult(statistic=-0.011239061725954754, pvalue=1.637324987020833e-17)

In [28]:

mask = mass > 1e12
plt.figure()
plt.hexbin(np.log10(mass), velmag, mincnt=1, bins="log")

plt.xlabel(r"$\log M_{\rm FoF} ~ [M_\odot / h]$")
plt.ylabel(r"$|\mathbf{V}| ~ [\mathrm{km} / \mathrm{s}]$")

plt.savefig("../plots/velocity_mass.png", dpi=300, bbox_inches="tight")
plt.show()

In [ ]: