path: root/calc_overdensity.py

#!/usr/bin/env python3
#
# Aaron LI
# Created: 2016-06-30
# Updated: 2016-07-13
#
# Change logs:
# 2016-07-13:
#   * Use class 'SmoothSpline' from module 'spline.py'
# 2016-07-11:
#   * Use a default config to allow a minimal user config
# 2016-07-04:
#   * Fix a bug with wrong variable
#   * Update radii to unit "kpc" and mass to unit "Msun"
#

"""
Calculate the overdensity profile, and from which to calculate the
R_{500} (defined as the radius of the sphere that encloses a mean total
mass density of 500 times the critical density at the cluster's redshift)
and M_gas_{500}/M_{500} (the enclosed gas/total mass by a sphere of radius
R_{500}).


References:
[1] Ettori et al., 2013, Space Science Review, 177, 119-154
"""


import argparse
import json
from collections import OrderedDict

import numpy as np
import scipy.optimize as optimize
import astropy.units as au
from astropy.cosmology import FlatLambdaCDM
from configobj import ConfigObj

from astro_params import AstroParams
from spline import SmoothSpline


config_default = """
## Configuration for `calc_overdensity.py`

# redshift of the source (critical density)
#redshift = <REDSHIFT>

# gas mass profile
m_gas_profile = mass_gas_profile.txt

# output total (gravitational) mass profile
m_total_profile = mass_total_profile.txt

# number of times w.r.t the critical density
delta = 1500, 500, 200

# output results in JSON format
outfile = overdensity.json

# output overdensity profile
overdensity_profile = overdensity_profile.txt
"""


class MassProfile:
    """
    Cluster's gas/total integrated mass profile.

    The total/gravitational mass profile is required to calculate
    the overdensity profile, from which the R_{delta} is then determined.
    """
    # supported types of mass profile
    MASS_TYPES = ["total", "gas"]
    # available splines
    SPLINES = ["mass", "overdensity"]
    # input mass data: [r, r_err, m]
    r = None
    r_err = None
    m = None
    # redshift of the object
    redshift = None
    # fitted smoothing spline
    m_spline = None
    od_spline = None

    def __init__(self, mass, mass_type="total"):
        self.load_data(data=mass, mass_type=mass_type)

    def load_data(self, data, mass_type="total"):
        if mass_type not in self.MASS_TYPES:
            raise ValueError("invalid mass_types: %s" % mass_type)
        # 3-column mass profile: r[kpc], r_err[kpc], mass[Msun]
        self.r = data[:, 0].copy()
        self.r_err = data[:, 1].copy()
        self.m = data[:, 2].copy()
        self.mass_type = mass_type

    def calc_overdensity(self, z, verbose=True):
        """
        Calculate the overdensity profile from the total/gravitational
        mass profile.

        The overdensity is the ratio of the enclosed mean total mass
        density to the critical density at the source's redshift.
        """
        if self.mass_type != "total":
            raise ValueError("total mass profile is required")
        #
        if verbose:
            print("Calculating the overdensity profile ...")
        overdensity = np.zeros(self.r.shape)
        # critical density
        cosmo = FlatLambdaCDM(H0=AstroParams.H0, Om0=AstroParams.OmegaM0)
        d_crit = cosmo.critical_density(z).cgs.value  # [ g/cm^3 ]
        for i, r in enumerate(self.r):
            volume = (4.0/3.0) * np.pi * (r*au.kpc.to(au.cm))**3
            mass = self.m[i] * au.solMass.to(au.g)
            overdensity[i] = mass / volume / d_crit
        self.overdensity = overdensity
        return overdensity

    def calc_radius_delta(self, delta):
        """
        Calculate the radius at which the overdensity is delta.
        """
        if self.od_spline is None:
            self.fit_spline(spline="overdensity", log10=["x", "y"])
        if min(self.overdensity) > delta:
            raise ValueError("min(overdensity) > %d" % delta)
        r = optimize.newton(
            lambda x: self.eval_spline("overdensity", x) - delta,
            x0=500.0, tol=1e-2)
        return r

    def calc_mass_delta(self, r_delta):
        if self.m_spline is None:
            self.fit_spline(spline="mass", log10=["x", "y"])
        return self.eval_spline(spline="mass", x=r_delta)

    def save(self, outfile):
        """
        Save calculated overdensity profile.
        """
        data = np.column_stack([self.r,
                                self.r_err,
                                self.overdensity])
        header = "radius[kpc]  radius_err[kpc]  overdensity"
        np.savetxt(outfile, data, header=header)

    def fit_spline(self, spline, log10=[]):
        if spline not in self.SPLINES:
            raise ValueError("invalid spline: %s" % spline)
        #
        if spline == "mass":
            # input gas/total mass profile
            x = self.r
            y = self.m
            spl = "m_spline"
        elif spline == "overdensity":
            # calculated overdensity profile
            x = self.radius
            y = self.rho_total
            spl = "od_spline"
        else:
            raise ValueError("invalid spline: %s" % spline)
        setattr(self, spl, SmoothSpline(x=x, y=y))
        getattr(self, spl).fit(log10=log10)

    def eval_spline(self, spline, x):
        """
        Evaluate the specified spline at the supplied positions.
        Also check whether the spline was fitted in the log-scale space,
        and transform the evaluated values if necessary.
        """
        if spline == "mass":
            spl = self.m_spline
        elif spline == "overdensity":
            spl = self.od_spline
        else:
            raise ValueError("invalid spline: %s" % spline)
        #
        return spl.eval(x)


def main():
    parser = argparse.ArgumentParser(
            description="Calculate overdensity profile and R_{500} etc.")
    parser.add_argument("config", nargs="?", default="overdensity.conf",
                        help="config for overdensity profile and R_{500} " +
                             "etc. calculation (default: overdensity.conf)")
    args = parser.parse_args()

    config = ConfigObj(config_default.splitlines())
    config_user = ConfigObj(args.config)
    config.merge(config_user)

    redshift = config.as_float("redshift")
    m_gas_data = np.loadtxt(config["m_gas_profile"])
    m_total_data = np.loadtxt(config["m_total_profile"])
    delta = list(map(int, config.as_list("delta")))

    m_total_profile = MassProfile(mass=m_total_data, mass_type="total")
    m_total_profile.calc_overdensity(z=redshift, verbose=True)
    m_total_profile.save(outfile=config["overdensity_profile"])

    m_gas_profile = MassProfile(mass=m_gas_data, mass_type="gas")

    results = OrderedDict()
    results["redshift"] = redshift

    for d in delta:
        r_delta = m_total_profile.calc_radius_delta(delta=d)
        m_total_delta = m_total_profile.calc_mass_delta(r_delta)
        m_gas_delta = m_gas_profile.calc_mass_delta(r_delta)
        results["R%d[kpc]" % d] = r_delta
        results["Mtotal%d[Msun]" % d] = m_total_delta
        results["Mgas%d[Msun]" % d] = m_gas_delta

    results_json = json.dumps(results, indent=2)
    print(results_json)
    open(config["outfile"], "w").write(results_json+"\n")


if __name__ == "__main__":
    main()