csiborgtools/galomatch/units/box_units.py
Richard Stiskalek 942c36b142
Box units conversion (#3)
* linting

* fix long line

* rename nb

* rename import

* add group catalog

* move imports out of functions

* add array_to_structured

* add references

* fix subsampling

* fix coord bug

* add 2M++ dists

* save nb

* fix comment

* add snapshot path

* add snapshot path

* add read_info

* Move transforms

* add import radec

* expand docs

* Move flipcols

* update nb

* add flip_cols

* create file

* add blank line

* Move units transfs

* add blank line

* add units import

* rm imports

* add import

* add box_units

* add comments
2022-10-20 23:28:44 +01:00

166 lines
4.5 KiB
Python

# Copyright (C) 2022 Richard Stiskalek, Deaglan Bartlett
# This program is free software; you can redistribute it and/or modify it
# under the terms of the GNU General Public License as published by the
# Free Software Foundation; either version 3 of the License, or (at your
# option) any later version.
#
# This program is distributed in the hope that it will be useful, but
# WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General
# Public License for more details.
#
# You should have received a copy of the GNU General Public License along
# with this program; if not, write to the Free Software Foundation, Inc.,
# 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
"""
Simulation box unit transformations.
"""
from astropy.cosmology import LambdaCDM
from astropy import (constants, units)
from ..io import read_info
# Conversion factors
MSUNCGS = constants.M_sun.cgs.value
KPC_TO_CM = 3.08567758149137e21
PI = 3.1415926535897932384626433
class BoxUnits:
"""
Box units class for converting between box and physical units.
Paramaters
----------
Nsnap : int
Snapshot index.
simpath : str
Path to the simulation where its snapshot index folders are stored.
"""
def __init__(self, Nsnap, simpath):
"""
Read in the snapshot info file and set the units from it.
"""
info = read_info(Nsnap, simpath)
pars = ["boxlen", "time", "aexp", "H0",
"omega_m", "omega_l", "omega_k", "omega_b",
"unit_l", "unit_d", "unit_t"]
for par in pars:
setattr(self, par, float(info[par]))
self.h = self.H0 / 100
self.cosmo = LambdaCDM(H0=self.H0, Om0=self.omega_m, Ode0=self.omega_l,
Tcmb0=2.725 * units.K, Ob0=self.omega_b)
# Constants in box units
self.G = constants.G.cgs.value * (self.unit_d * self.unit_t ** 2)
self.H0 = self.H0 * 1e5 / (1e3 * KPC_TO_CM) * self.unit_t
self.c = constants.c.cgs.value * self.unit_t / self.unit_l
self.rho_crit = 3 * self.H0 ** 2 / (8 * PI * self.G)
def box2kpc(self, length):
r"""
Convert length from box units to :math:`\mathrm{kpc}`.
Parameters
----------
length : float
Length in box units.
Returns
-------
length : foat
Length in :math:`\mathrm{kpc}`
"""
return length * self.unit_l / KPC_TO_CM
def kpc2box(self, length):
r"""
Convert length from :math:`\mathrm{kpc}` to box units.
Parameters
----------
length : float
Length in :math:`\mathrm{kpc}`
Returns
-------
length : foat
Length in box units.
"""
return length / self.unit_l * KPC_TO_CM
def solarmass2box(self, mass):
r"""
Convert mass from :math:`M_\odot` to box units.
Parameters
----------
mass : float
Mass in :math:`M_\odot`.
Returns
-------
mass : float
Mass in box units.
"""
m = mass * MSUNCGS # In cgs
unit_m = self.unit_d * self.unit_l ** 3
return m / unit_m
def box2solarmass(self, mass):
r"""
Convert mass from box units to :math:`M_\odot`.
TODO: check this.
Parameters
----------
mass : float
Mass in box units.
Returns
-------
mass : float
Mass in :math:`M_\odot`.
"""
unit_m = self.unit_d * self.unit_l**3
m = mass * unit_m # In cgs
m = m / MSUNCGS
return m
def box2dens(self, density):
r"""
Convert density from box units to :math:`M_\odot / \mathrm{pc}^3`.
TODO: check this.
Parameters
----------
density : float
Density in box units.
box : `BoxConstants`
Simulation box class with units.
Returns
-------
density : float
Density in :math:`M_\odot / \mathrm{pc}^3`.
"""
rho = density * self.unit_d # In cgs
rho = rho * (KPC_TO_CM * 1e-3)**3 # In g/pc^3
rho = rho / MSUNCGS
return rho
def dens2box(self, density):
r"""
Convert density from M_sun / pc^3
TODO: check this and write documentation.
"""
rho = density * MSUNCGS
rho = rho / (KPC_TO_CM * 1e-3)**3 # In g/cm^3
rho = rho / self.unit_d
return rho