Cosmology
H
0
[km/s/Mpc]
Ω
m
Ω
Λ
Flat (Ω
Λ
= 1 − Ω
m
)
Redshift z
Overdensity definition
Δ
relative to
critical (ρc)
mean matter (ρm)
Convert (edit either field)
M [M
⊙
]
R
unit
pc
kpc
Mpc
frame
physical
comoving
Use h
−1
units (M in M
⊙
/h, R in kpc/h etc.)
Accepts scientific notation, e.g. 3.5e14.
Halo
Assumptions
M = (4π/3) Δ ρ
ref
(z) R³, with ρ
c
(z) = 3H(z)²/8πG and ρ
m
(z) = Ω
m
(1+z)³ρ
c,0
. No halo profile is assumed, so this cannot convert between different Δ for the same halo.
ΛCDM (w = −1); radiation and neutrinos neglected.
“vir” is the Bryan & Norman (1998) flat-ΛCDM fit.