Fitting routines

GOAL:

Step through bins (spectra) and calculate the temperature value of each bin using XSPEC

OUTPUTS:

A file which contains the bin number and associated temperature and reduced chi-squared

ADDITIONAL NOTES:

Be sure to run heainit first

TemperatureMapPipeline.Fits.FitXSPEC(spectrum_files, background_files, redshift, n_H, temp_guess, grouping, spec_count, plot_dir, errors=False)

Fit observations simultaneously using models defined in obsid_set().

Parameters

  • spectrum_files (list) – List of spectrum files (i.e. [‘obs1.pi’, ‘obs2.pi’])

  • background_files (list) – List of background files (i.e. [‘obs1_bkg.pi’, ‘obs2_bkg.pi’])

  • redshift (float) – Cosmological Redshift of Object

  • n_H (float) – Column Density in direction of object – units of 10^{-22} cm^{-2}

  • Temp_guess (float) – Estimate of Temperature Value

  • grouping (int) – Number of counts per bin (i.e. 5)

  • spec_count (int) – Local number of spectra with reference to the total number of spectra being fitted

  • plot_dir (str) – Path to directory containing plots

Kwargs:

errors (bool): Boolean to calculate 1-sigma errors (default=False)

Returns

Fitted Temperature Value in keV Temp_min: Minimum Fitted Temperature Value at 1-sigma in keV Temp_max: Maximum Fitted Temperature Value at 1-sigma in keV Abundance: Fitted Abundance Value in Z_{solar} Ab_min: Minimum Fitted Abundance Value at 1-sigma in Z_{solar} Ab_max: Maximum Fitted Abundance Value at 1-sigma in Z_{solar} Norm: Fitted Normalization Value Norm_min: Minimum Fitted Normalization Value at 1-sigma norm_max: Maximum Fitted Normalization Value at 1-sigma reduced_chi_sq: Reduced Chi Square Value for the Fit Flux: Fitted Flux Value in ergs/s/cm^{-2} Flux_min: Minimum Flux Value in ergs/s/cm^{-2} Flux_max: Maximum Flux Value in ergs/s/cm^{-2}

Return type

Temperature

Note

If the fits are taking too long, set errors=False. The min and max value will just be copies of the fitted value.

Flux errors are always calculated

TemperatureMapPipeline.Fits.Fitting(base_directory, dir, file_name, num_files, redshift, n_H, temp_guess, output_file, bin_spec_dir)

Fit each region’s spectra and create a text file containing the spectral fit information for each bin :param base_directory: Path to main Directory :param dir: ObsID :param file_name: Root name of PI/PHA file :param num_files: Number of spatial bins :param redshift: Redshift of cluster :param n_H: Column density :param temp_guess: Initial temperature guess :param output_file: Text file containing each bin’s spectral fit information :param bin_spec_dir: Path to extracted spectra for each bin within an ObsID

Returns

None

TemperatureMapPipeline.Fits.concat_temp_data(num_spec, output_file)

Concatenate temperature information. Used if running on several processors :param num_spec: Number of spectra (or bins) :param output_file: File name of final concatenated temperature data

TemperatureMapPipeline.Fits.fit_loop(dir, bin_spec_dir, file_name, redshift, n_H, temp_guess, grouping, plot_dir, base_directory, i)

Loop for fitting spectra. This will simply call the FitXSPEC function and write out the results to a temporary file

Parameters

  • bin_spec_dir – Path to extracted spectra for each bin within an ObsID

  • dir (str) – ObsID

  • file_name (str) – Root name of PI/PHA file

  • redshift (float) – Cosmological Redshift of Object

  • n_H (float) – Column Density in direction of object – units of 10^{-22} cm^{-2}

  • Temp_guess (float) – Estimate of Temperature Value

  • grouping (int) – Number of counts per bin (i.e. 5)

  • plot_dir (str) – Path to plots

  • base_directory (str) – Path to main Directory

  • i (int) – Relative spectrum number

Returns

None

TemperatureMapPipeline.Fits.obsid_set(src_model_dict, bkg_model_dict, obsid, bkg_spec, obs_count, redshift, nH_val, Temp_guess)

Set the observations’ model using an absorbed apec model. Each observation will be tied with the other to allow simultaneous fitting.

We additionally apply a background model.

It contains two (frozen) thermal emission pieces:

  1. unabsorbed apec model with kT=0.18 keV

  2. absorbed bremmstrahlung emission with kT=40 keV

Parameters

  • src_model_dict (dict) – Dictionary of source models – Created in FitXSPEC()

  • bkg_model_dict (dict) – Dictionary of background models – Created in FitXSPEC()

  • obsid (str) – Current Chandra ObsID

  • bkg_spec (str) – Background file corresponding to ObsID

  • obs_ct (int) – Relative ObsID number

  • redshift (float) – Cosmological Redshift of Object

  • nH_val (float) – Column Density in direction of object – units of 10^{-22} cm^{-2}

  • Temp_guess (float) – Estimate of Temperature Value

Returns

Updated src_model_dict and bkg_model_dict