#!/usr/bin/env python3 # # Aaron LI # Created: 2016-06-10 # Updated: 2016-07-15 # # Change logs: # 2016-07-15: # * Do not repeat electron number density calculation # 2016-07-11: # * Use a default config to allow a minimal user config # 2016-07-10: # * Use class 'SmoothSpline' from module # 2016-07-04: # * Use model's "report()" method # * Add config "sbpexp_rcut" # * Rename config "sbpexp_rcut*" to "sbpexp_rignore*" # * Save profile radii in unit "kpc" # * Update to that cooling function profile's radius in unit "kpc" # 2016-06-27: # * Minor cleanups # * Remove obsolete class "DeprojectSBP" # * Fit smoothing spline to SBP and cooling function profiles by # calling the R `mgcv::gam()`: "fit_spline()" and "eval_spline()" # * Update "plot()" to also plot the fitted smoothing spline # 2016-06-26: # * Split out method "save()" for class "BrightnessProfile" # * Split classes 'FitModel', 'ABModel' and 'PLCModel' into separate # module 'fitting_models.py' # 2016-06-25: # * Use 'InterpolatedUnivariateSpline' instead of 'interp1d' # 2016-06-24: # * Move class 'ChandraPixel' to module 'astro_params.py' # * Split class 'Projection' to a separate module 'projection.py' # * Move class 'DensityProfile' to tool 'calc_mass_potential.py' # * Split class 'AstroParams' to separate module 'astro_params.py' # 2016-06-23: # * Add configuration parameter 'sbpexp_rcut' # * Allow extrapolate the cooling function profile # * Add plot function to class 'BrightnessProfile' # * Update sample configuration file # * Remove obsolete class 'SurfaceBrightnessProfile' # 2016-06-22: # * Add class 'DensityProfile', the inversion to 'BrightnessProfile' # * Add classes 'AstroParams' and 'BrightnessProfile' # * Add class 'ChandraPixel' # * Update documentation # 2016-06-21: # * Add document about the gas density derivation # 2016-06-20: # * Use configuration file instead of the tedious command line arguments # 2016-06-16: # * Add methods 'save()', 'report()' and 'plot()' to class 'SBP' # 2016-06-15: # * Add command line arguments # * Add class 'SBP' for SBP background subtraction and extrapolation # 2016-06-14: # * Add class 'PLCModel' based on 'FitModel' # * Split class 'FitModel' from 'ABModel' # 2016-06-13: # * Add class 'ABModel' to support data scaling # * Implement primitive SBP deprojection approach for class 'DeprojectSBP' # """ Deproject the 2D surface brightness profile (SBP) into ??? The SBP deprojection is performed using a non-parametric approach with regularization which add the constraint that the 3D gas density profile should be smooth. ======================================================================= Surface brightness (`SUR_FLUX` column of the dmextract'ed radial profile): Brightness: [ photon s^-1 cm^-2 pixel^-2 ] where the 'cm^-2' is due to the instrumental effective area, and the 'pixel^-2' is corresponding to the solid angle with respect to the source (i.e., [ arcsec^-2 ]). The flux has dimension: Flux: [ photon s^-1 cm^-2 ] therefore, the dimension of brightness can also be expressed as: Brightness: [ Flux pixel^-2 ] = [ Flux sr^-1 ] The instrument and (time-normalized) exposure map has dimension: [ count photon^-1 cm^2 ] which is used to convert the instrument-specific counts image into physical- meaningful flux unit. Emission measure: EM = \int n_e n_H dV ~= (n_e^2 / ratio_eH) V [ cm^-3 ] where 'ratio_eH' is the ratio of electron density to proton density (n_H). APEC normalization returned by XSPEC is simply the *emission measure* of the gas scaled by the distance: eta = (\int n_e n_H dV) / (4 pi (D_A (1+z))^2) assuming (ref. [4]): n_H ~= 0.826 n_e then the gas density (n_H or n_e) can be calculated. The flux calculated with the XSPEC `flux` command has dimension: Flux: [ photon s^-1 cm^-2 ] or [ erg s^-2 cm^-2 ] When use XSPEC APEC model to calculate the cooling function (Lambda), its normalization is calculated with EM = 1, therefore: norm = 1e-14 / (4 pi (D_A (1+z))^2) * EM = 1e-14 / (4 pi (D_A (1+z))^2) [ cm^-5 ] where the 'D_A' is the angular diameter distance which can be simply calculated from its redshift. With the Galactic absorption (nH), temperature (varies with radius), and abundance (assumed constant) been set, the cooling function is derived by using the XSPEC `flux` command. Therefore, cooling function has dimension: Lambda: [ Flux EM^-1 ] By deprojecting the surface brightness, the flux per volume can be derived, and EM can be further obtained by incorporating the cooling function, and finally the (3D) gas density can be determined. (projection): EM * Lambda / A -> Brightness where 'A' is the solid angle (i.e., area covered by the source). ======================================================================= References: [1] Croston et al. 2006, A&A, 459, 1007-1019 [2] McLaughlin, 1999, ApJ, 117, 2398-2427 [3] Bouchet, 1995, A&AS, 113, 167 [4] Ettori et al, 2013, Space Science Review, 177, 119-154 [5] AtomDB / APEC model: * http://www.atomdb.org/faq.php#DensityXSPECnorm * https://heasarc.gsfc.nasa.gov/docs/xanadu/xspec/manual/XSmodelApec.html """ import argparse import json from collections import OrderedDict import astropy.units as au import numpy as np import pandas as pd import matplotlib.pyplot as plt from matplotlib.backends.backend_agg import FigureCanvasAgg as FigureCanvas from matplotlib.figure import Figure from configobj import ConfigObj from astro_params import AstroParams, ChandraPixel from projection import Projection from fitting_models import PLCModel from spline import SmoothSpline plt.style.use("ggplot") config_default = """ ## Configuration for `deproject_sbp.py` # config file for SBP fitting (e.g., sbpfit.conf) sbpfit_config = sbpfit.conf # input cooling function profile coolfunc_profile = coolfunc_profile.txt # redshift of the object (for pixel to distance conversion) #redshift = ## SBP extrapolation # ignorance radius from which the SBP is fitted for extrapolation, # specified by the ratio w.r.t sbpfit rc (default: 1.2 * rc) sbpexp_rignore_ratio = 1.2 # or directly specify the ignorance radius (override above) (unit: pixel) #sbpexp_rignore = # cut radius to which stop the extrapolation (unit: kpc) sbpexp_rcut = 3000 # output of the extrapolated SBP sbpexp_outfile = sbpexp.csv # extrapolation model information sbpexp_json = sbpexp.json # plot of the SBP extrapolation sbpexp_image = sbpexp.png ## Density profiles # deprojected 3D electron number density profile ne_profile = ne_profile.txt # deprojected 3D gas mass density profile rho_gas_profile = rho_gas_profile.txt # image of the density profiles (electron density and/or gas density) density_profile_image = density_profile.png """ class SBP: """ X-ray surface brightness profile class. This class deals with SBP background subtraction and SBP extrapolation. """ # input SBP data: [r, r_err, s, s_err] r = None r_err = None s = None s_err = None # uniform background been subtracted bkg = None # ignorance/minimal radius from which the SBP is fitted to the PLCModel rignore = None # cut radius where the extrapolation stops rcut = None # PLCModel instance used to extrapolate the SBP plcmodel = None def __init__(self, r, r_err=None, s=None, s_err=None, rignore=None): self.load_data(r=r, r_err=r_err, s=s, s_err=s_err, rignore=rignore) self.plcmodel = PLCModel(scale=True) def load_data(self, r, r_err=None, s=None, s_err=None, rignore=None): if r.ndim == 2 and r.shape[1] == 4: # 4-column data self.r = r[:, 0].copy() self.r_err = r[:, 1].copy() self.s = r[:, 2].copy() self.s_err = r[:, 3].copy() else: self.r = np.array(r) self.r_err = np.array(r_err) self.s = np.array(s) self.s_err = np.array(s_err) self.rignore = rignore def subtract_bkg(self, bkg): """ Subtract the uniform background from the brightness. The value of background can be acquired by fitting the whole or core-exclude SBP with model consisting of a plain beta model and a constant. The "AB model" maybe also applicable. """ self.bkg = bkg self.s -= bkg self.bkg_subtracted = True def extrapolate(self, rignore=None, rcut=None): """ Extrapolate the SBP by assuming that the outer SBP follows the following relation: S_X = A * r^{-alpha}, which can be determined by model fitting. The SBP is extrapolated to the region where the brightness is lower than the current observed minimal brightness by one order of magnitude, and the extrapolated SBP bins have the same width and relative errors as the last SBP bin observed. If the 'rcut' is specified, then the SBP extrapolation stops when exceeds that radius. Note that the uniform background should be subtracted first. Return: * self.r_extrapolated * self.r_err_extrapolated * self.s_extrapolated * self.s_err_extrapolated * self.mask_extrapolated """ if rignore is not None: self.rignore = rignore if rcut is not None: self.rcut = rcut self.mask = self.r >= self.rignore self.plcmodel.load_data(xdata=self.r[self.mask], ydata=self.s[self.mask], xerr=self.r_err[self.mask], yerr=self.s_err[self.mask], update_params=True) self.plcmodel.set_param("bkg", value=0.0, vary=False) self.plcmodel.fit() last_r_err = self.r_err[-1] last_s = self.s[-1] last_s_err = self.s_err[-1] # r_exp = self.r.tolist() r_err_exp = self.r_err.tolist() s_exp = self.s.tolist() s_err_exp = self.s_err.tolist() mask_exp = [False] * len(r_exp) # do extrapolation r_tmp = r_exp[-1] + 2*r_err_exp[-1] s_tmp = self.plcmodel.f(r_tmp) while True: if rcut is not None and r_tmp > rcut: break if rcut is None and (s_tmp < last_s / 10.0): break r_exp.append(r_tmp) r_err_exp.append(last_r_err) s_exp.append(s_tmp) s_err_exp.append(s_tmp * last_s_err / last_s) mask_exp.append(True) r_tmp = r_exp[-1] + 2*r_err_exp[-1] s_tmp = self.plcmodel.f(r_tmp) # convert to numpy array self.r_extrapolated = np.array(r_exp) self.r_err_extrapolated = np.array(r_err_exp) self.s_extrapolated = np.array(s_exp) self.s_err_extrapolated = np.array(s_err_exp) self.mask_extrapolated = np.array(mask_exp) def report(self, outfile=None): """ Report the extrapolation model fitting results. """ results = OrderedDict([ ("bkg", self.bkg), ("bkg_subtracted", self.bkg_subtracted), ("rignore", self.rignore), ("rcut", self.rcut), ("model", self.plcmodel.name), ("fitting", self.plcmodel.report(rtype="fitting")), ("params", self.plcmodel.report(rtype="parameters")), ]) results_json = json.dumps(results, indent=2) if outfile is None: print(results_json) else: open(outfile, "w").write(results_json+"\n") def plot(self, ax=None, fig=None): """ Make a plot of the SBP extrapolation. """ if ax is None: fig, ax = plt.subplots(1, 1) # ignored data points mask_ignore = np.logical_not(self.mask) if np.sum(mask_ignore) > 0: ax.errorbar(self.r[mask_ignore], self.s[mask_ignore], xerr=self.r_err[mask_ignore], yerr=self.s_err[mask_ignore], fmt="none", elinewidth=1, capthick=1) # data points used to fit the PLC model ax.errorbar(self.r[self.mask], self.s[self.mask], xerr=self.r_err[self.mask], yerr=self.s_err[self.mask], fmt="none", elinewidth=2, capthick=2) # extrapolated data points ax.errorbar(self.r_extrapolated[self.mask_extrapolated], self.s_extrapolated[self.mask_extrapolated], xerr=self.r_err_extrapolated[self.mask_extrapolated], yerr=self.s_err_extrapolated[self.mask_extrapolated], fmt="none", elinewidth=1, capthick=1) # original data points without background subtraction eb = ax.errorbar(self.r, self.s+self.bkg, xerr=self.r_err, yerr=self.s_err, fmt="none", elinewidth=1, capthick=1) eb[-1][0].set_linestyle("dashdot") eb[-1][1].set_linestyle("dashdot") # PLC model mask_fit = self.mask_extrapolated.copy() mask_fit[:len(self.mask)] = self.mask r_fit = self.r_extrapolated[mask_fit] s_fit = self.plcmodel.f(r_fit) ax.plot(r_fit, s_fit, color="black", linestyle="solid") # adjust layout r_min = 1.0 r_max = self.r_extrapolated[-1] + self.r_err_extrapolated[-1] s_min = min(self.s_extrapolated) / 1.2 s_max = max(self.s_extrapolated + self.s_err_extrapolated) * 1.2 ax.set_xscale("log") ax.set_yscale("log") ax.set_xlim(r_min, r_max) ax.set_ylim(s_min, s_max) # labels ax.set_xlabel("Radius (%s)" % "pixel") ax.set_ylabel(r"Surface Brightness (photons/cm$^2$/pixel$^2$/s)") ax.text(x=r_max/1.2, y=s_max/1.2, s=r"reduced $\chi^2$: %.2f / %.2f = %.2f" % ( self.plcmodel.fitted.chisqr, self.plcmodel.fitted.nfree, self.plcmodel.fitted.chisqr/self.plcmodel.fitted.nfree), horizontalalignment="right", verticalalignment="top") fig.tight_layout() return (fig, ax) def get_data(self): """ Get the extrapolated data, for following use. """ return np.column_stack([self.r_extrapolated, self.r_err_extrapolated, self.s_extrapolated, self.s_err_extrapolated]) def save(self, outfile): """ Save the (extrapolated) SBP to the given output file in CSV format. """ df = pd.DataFrame() df["radius"] = self.r_extrapolated df["radius_err"] = self.r_err_extrapolated df["brightness"] = self.s_extrapolated df["brightness_err"] = self.s_err_extrapolated df["flag_extrapolation"] = self.mask_extrapolated flag_fit = np.zeros(self.mask_extrapolated.shape, dtype=bool) flag_fit[:len(self.mask)] = self.mask df["flag_fit"] = flag_fit df.to_csv(outfile, header=True, index=False) class BrightnessProfile: """ Calculate the electron number density and/or gas mass density profile by deprojecting the observed X-ray surface brightness profile and incorporating the cooling function profile. NOTE: * The radii should have unit [ pixel ] (Chandra pixel) * The brightness should have unit [ photon s^-1 cm^-2 pixel^-2 ], i.e., [ Flux pixel^-2 ] (radial profile column `SUR_FLUX`) """ # available splines SPLINES = ["brightness", "cooling_function"] # allowed density profile types DENSITY_TYPES = ["electron", "gas"] # input SBP data: [r, r_err, s, s_err] r = None r_err = None s = None s_err = None # redshift of the source z = None # `ChandraPixel` instance for unit conversion pixel = None # flag to indicate whether the units are converted units_converted = False # calculated electron density profile ne = None # calculated gas mass density profile rho_gas = None # fitted `SmoothSpline` object of the SBP s_spline = None # fitted `SmoothSpline` of the cooling function profile cf_spline = None def __init__(self, sbp_data, cf_data, z): self.load_data(data=sbp_data) self.load_cf_data(data=cf_data) self.z = z self.pixel = ChandraPixel(z) def load_data(self, data): # 4-column SBP: [r, r_err, brightness, brightness_err] self.r = data[:, 0].copy() self.r_err = data[:, 1].copy() self.s = data[:, 2].copy() self.s_err = data[:, 3].copy() def load_cf_data(self, data): # 2-column cooling function profile self.cf_radius = data[:, 0].copy() self.cf_value = data[:, 1].copy() def convert_units(self): """ Convert the units of SBP: radius: pixel -> cm brightness: Flux / pixel**2 -> Flux / cm**2 Convert the units of cooling function profile: radius: kpc -> cm """ if not self.units_converted: cm_per_pixel = self.pixel.get_length().to(au.cm).value self.r *= cm_per_pixel self.r_err *= cm_per_pixel self.s /= cm_per_pixel**2 self.s_err /= cm_per_pixel**2 # cooling function profile: kpc -> cm self.cf_radius *= au.kpc.to(au.cm) self.units_converted = True def get_radius(self): return (self.r.copy(), self.r_err.copy()) def fit_spline(self, spline, log10=[]): if spline not in self.SPLINES: raise ValueError("invalid spline: %s" % spline) # if spline == "brightness": x = self.r y = self.s weights = self.s / self.s_err spl = "s_spline" elif spline == "cooling_function": x = self.cf_radius y = self.cf_value weights = None spl = "cf_spline" setattr(self, spl, SmoothSpline(x=x, y=y, weights=weights)) 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 == "brightness": spl = self.s_spline elif spline == "cooling_function": spl = self.cf_spline else: raise ValueError("invalid spline: %s" % spline) return spl.eval(x) def calc_electron_density(self): """ Deproject the surface brightness profile to derive the 3D electron number density (and then gas mass density) profile by incorporating the cooling function profile. unit: [ cm^-3 ] if the units converted for input data """ if self.s_spline is None: self.fit_spline(spline="brightness", log10=["x", "y"]) if self.cf_spline is None: self.fit_spline(spline="cooling_function", log10=[]) # s_new = self.eval_spline(spline="brightness", x=self.r) cf_new = self.eval_spline(spline="cooling_function", x=self.r) # projector = Projection(rout=self.r+self.r_err) s_deproj = projector.deproject(s_new) # emission measure per unit volume em_v = s_deproj / cf_new ne = np.sqrt(em_v * AstroParams.ratio_ne_np) self.ne = ne return ne def calc_gas_density(self): """ Calculate the gas mass density based the calculated electron number density. unit: [ g cm^-3 ] if the units converted for input data """ if self.ne is None: self.calc_electron_density() rho_gas = self.ne * AstroParams.mu_e * AstroParams.m_atom self.rho_gas = rho_gas return rho_gas def save(self, density_type, outfile): if density_type == "electron": data = np.column_stack([self.r * au.cm.to(au.kpc), self.r_err * au.cm.to(au.kpc), self.ne]) header = "radius[kpc] radius_err[kpc] " + \ "electron_number_density[cm^-3]" elif density_type == "gas": data = np.column_stack([self.r * au.cm.to(au.kpc), self.r_err * au.cm.to(au.kpc), self.rho_gas]) header = "radius[kpc] radius_err[kpc] " + \ "gas_mass_density[g/cm^3]" else: raise ValueError("unknown density_type: %s" % density_type) np.savetxt(outfile, data, header=header) def plot(self, ax=None, fig=None, density_type="electron"): if density_type not in self.DENSITY_TYPES: raise ValueError("invalid density_types: %s" % density_type) if density_type == "electron": density = self.ne d_name = "Deprojected electron number density" d_unit = "cm$^{-3}$" else: density = self.rho_gas d_name = "Deprojected gas mass density" d_unit = "g/cm$^3$" # if self.units_converted: # convert from [cm] to [kpc] r = self.r * au.cm.to(au.kpc) r_err = self.r_err * au.cm.to(au.kpc) r_unit = "kpc" s_unit = "flux/cm$^2$" else: r = self.r r_err = self.r_err r_unit = "pixel" s_unit = "flux/pixel$^2$" # if ax is None: fig, ax = plt.subplots(1, 1) # SBP data points eb = ax.errorbar(r, self.s, xerr=r_err, yerr=self.s_err, fmt="none", elinewidth=2, capthick=2, label="Brightness profile") # fitted smoothing spline to SBP s_new = self.eval_spline(spline="brightness", x=self.r) line1, = ax.plot(r, s_new, linestyle="dashed", linewidth=2, label="SBP smoothing spline") # r_min = 1.0 r_max = max(r + r_err) s_min = min(self.s) / 1.2 s_max = max(self.s + self.s_err) * 1.2 ax.set_xlim(r_min, r_max) ax.set_ylim(s_min, s_max) ax.set_xscale("log") ax.set_yscale("log") ax.set_xlabel("Radius (%s)" % r_unit) ax.set_ylabel(r"Surface brightness (%s)" % s_unit) # deprojected density profile ax2 = ax.twinx() line2, = ax2.plot(r, density, color="black", linestyle="solid", linewidth=2, label="Density profile") d_min = min(density) / 1.2 d_max = max(density) * 1.2 ax2.set_xlim(r_min, r_max) ax2.set_ylim(d_min, d_max) ax2.set_yscale(ax.get_yscale()) ax2.set_ylabel(r"%s (%s)" % (d_name, d_unit)) # legend handles = [eb, line1, line2] labels = [h.get_label() for h in handles] ax.legend(handles=handles, labels=labels, loc=0) fig.tight_layout() return (fig, ax, ax2) def main(): parser = argparse.ArgumentParser( description="Deproject the surface brightness profile (SBP)") parser.add_argument("config", nargs="?", default="sbpdeproj.conf", help="config for SBP deprojection " + "(default: sbpdeproj.conf)") args = parser.parse_args() config = ConfigObj(config_default.splitlines()) config_user = ConfigObj(open(args.config)) config.merge(config_user) sbpfit_conf = ConfigObj(open(config["sbpfit_config"])) try: sbpfit_outfile = sbpfit_conf[sbpfit_conf["model"]]["outfile"] except KeyError: sbpfit_outfile = sbpfit_conf["outfile"] sbpfit_results = json.load(open(sbpfit_outfile)) sbpdata = np.loadtxt(sbpfit_conf["sbpfile"]) rc = sbpfit_results["params"]["rc"][0] bkg = sbpfit_results["params"]["bkg"][0] redshift = config.as_float("redshift") pixel = ChandraPixel(redshift) print("SBP background subtraction and extrapolation ...") sbp = SBP(sbpdata) # ignorance radius rignore = rc * config.as_float("sbpexp_rignore_ratio") try: rignore = config.as_float("sbpexp_rignore") except KeyError: pass # cut radius where extrapolation stops (unit: kpc) try: rcut = config.as_float("sbpexp_rcut") # convert unit "kpc" -> "pixel" rcut /= pixel.get_length().to(au.kpc).value except KeyError: rcut = None sbp.subtract_bkg(bkg=bkg) sbp.extrapolate(rignore=rignore, rcut=rcut) sbp.save(outfile=config["sbpexp_outfile"]) sbp.report(outfile=config["sbpexp_json"]) fig = Figure(figsize=(10, 8)) FigureCanvas(fig) ax = fig.add_subplot(1, 1, 1) sbp.plot(ax=ax, fig=fig) fig.savefig(config["sbpexp_image"], dpi=150) print("SBP deprojection -> density profile ...") cf_data = np.loadtxt(config["coolfunc_profile"]) sbpdata_extrapolated = sbp.get_data() brightness_profile = BrightnessProfile(sbp_data=sbpdata_extrapolated, cf_data=cf_data, z=redshift) brightness_profile.convert_units() brightness_profile.calc_electron_density() brightness_profile.save(density_type="electron", outfile=config["ne_profile"]) brightness_profile.calc_gas_density() brightness_profile.save(density_type="gas", outfile=config["rho_gas_profile"]) fig = Figure(figsize=(10, 8)) FigureCanvas(fig) ax = fig.add_subplot(1, 1, 1) brightness_profile.plot(ax=ax, fig=fig) fig.savefig(config["density_profile_image"], dpi=150) if __name__ == "__main__": main()