Library of functions to fit lines¶

This class is dedicated to fitting lines on observed spectra.

class LineFittingLibrary.LineFittingLibrary[source]¶

This class contains a variety of function to fit emission or absorption lines in galaxy spectra.

class LineFittingLibrary.LineFittingLibrary(dV=-9999.99)[source]

Loads the environement proper to fit lines :

Gaussian line model
Lorentzian line model
pseudoVoigt line model
conversion magnitude AB to flux : flambda to fnu

Parameters:	dV – the default value (def: -9999.99)

fit_Line(wl, spec1d, err1d, a0, lineName='AL', fitWidth=20, DLC=20, p0_sigma=15.0, p0_flux=8e-17, p0_share=0.5, continuumSide='left', model='gaussian')[source]¶

fits a line profile to a spectrum around a fixed line position

Parameters:

Parameters:	wl – wavelength (array, Angstrom) spec1d – flux observed in the broad band (array, f lambda) err1d – error on the flux observed in the broad band (array, f lambda) a0 – expected position of the peak of the line in the observed frame (redshifted). a0 is not fitted, it is given. lineName – suffix characterizing the line in the headers of the output DLC – wavelength extent to fit the continuum around the line. (def: 230 Angstrom) p0_sigma – prior on the line width in A (def: 15 A) p0_flux – prior on the line flux in erg/cm2/s/A (def: 8e-17) p0_share – prior on the share of Gaussian and Lorentzian model. Only used if the line is fitted with a pseudoVoigt profile width (def: 0.5 no units) continuumSide – “left” = bluewards of the line or “right” = redwards of the line model – line model to be fitted : “gaussian”, “lorentz” or “pseudoVoigt”.

wl – wavelength (array, Angstrom)
spec1d – flux observed in the broad band (array, f lambda)
err1d – error on the flux observed in the broad band (array, f lambda)
a0 – expected position of the peak of the line in the observed frame (redshifted). a0 is not fitted, it is given.
lineName – suffix characterizing the line in the headers of the output
DLC – wavelength extent to fit the continuum around the line. (def: 230 Angstrom)
p0_sigma – prior on the line width in A (def: 15 A)
p0_flux – prior on the line flux in erg/cm2/s/A (def: 8e-17)
p0_share – prior on the share of Gaussian and Lorentzian model. Only used if the line is fitted with a pseudoVoigt profile width (def: 0.5 no units)
continuumSide – “left” = bluewards of the line or “right” = redwards of the line
model – line model to be fitted : “gaussian”, “lorentz” or “pseudoVoigt”.

Returns :

array 1 with the parameters of the model
array 2 with the model (wavelength, flux model)
header corresponding to the array 1

fit_Line_OIIdoublet(wl, spec1d, err1d, a0=3726.0321735398957, lineName='OII', fitWidth=20, DLC=20, p0_sigma=4.0, p0_flux=1e-16, p0_share=0.58, model='gaussian')[source]¶

fits the [OII] doublet line profile

Parameters:

Parameters:	wl – wavelength (array, Angstrom) spec1d – flux observed in the broad band (array, f lambda) err1d – error on the flux observed in the broad band (array, f lambda) a0 – expected position of the peak of the line in the observed frame (redshifted). 2 positions given. lineName – suffix characterizing the line in the headers of the output DLC – wavelength extent to fit the continuum around the line. (def: 230 Angstrom) p0_sigma – prior on the line width in A (def: 15 A) p0_flux – prior on the line flux in erg/cm2/s/A (def: 8e-17) p0_share – prior on the share between the two [OII] lines. (def: 0.58) continuumSide – “left” = bluewards of the line or “right” = redwards of the line model – line model to be fitted : “gaussian”, “lorentz” or “pseudoVoigt”

wl – wavelength (array, Angstrom)
spec1d – flux observed in the broad band (array, f lambda)
err1d – error on the flux observed in the broad band (array, f lambda)
a0 – expected position of the peak of the line in the observed frame (redshifted). 2 positions given.
lineName – suffix characterizing the line in the headers of the output
DLC – wavelength extent to fit the continuum around the line. (def: 230 Angstrom)
p0_sigma – prior on the line width in A (def: 15 A)
p0_flux – prior on the line flux in erg/cm2/s/A (def: 8e-17)
p0_share – prior on the share between the two [OII] lines. (def: 0.58)
continuumSide – “left” = bluewards of the line or “right” = redwards of the line
model – line model to be fitted : “gaussian”, “lorentz” or “pseudoVoigt”

Returns :

array 1 with the parameters of the model
array 2 with the model (wavelength, flux model)
header corresponding to the array 1

fit_Line_OIIdoublet_position(wl, spec1d, err1d, a0=3726.0321, lineName='O2_3728', fitWidth=20, DLC=20, p0_sigma=4.0, p0_flux=1e-16, p0_share=0.58, model='gaussian')[source]¶

fits the [OII] doublet line profile

Parameters:

Parameters:	wl – wavelength (array, Angstrom) spec1d – flux observed in the broad band (array, f lambda) err1d – error on the flux observed in the broad band (array, f lambda) a0 – expected position of the peak of the line in the observed frame (redshifted). 2 positions given. lineName – suffix characterizing the line in the headers of the output DLC – wavelength extent to fit the continuum around the line. (def: 230 Angstrom) p0_sigma – prior on the line width in A (def: 15 A) p0_flux – prior on the line flux in erg/cm2/s/A (def: 8e-17) p0_share – prior on the share between the two [OII] lines. (def: 0.58) continuumSide – “left” = bluewards of the line or “right” = redwards of the line model – line model to be fitted : “gaussian”, “lorentz” or “pseudoVoigt”

wl – wavelength (array, Angstrom)
spec1d – flux observed in the broad band (array, f lambda)
err1d – error on the flux observed in the broad band (array, f lambda)
a0 – expected position of the peak of the line in the observed frame (redshifted). 2 positions given.
lineName – suffix characterizing the line in the headers of the output
DLC – wavelength extent to fit the continuum around the line. (def: 230 Angstrom)
p0_sigma – prior on the line width in A (def: 15 A)
p0_flux – prior on the line flux in erg/cm2/s/A (def: 8e-17)
p0_share – prior on the share between the two [OII] lines. (def: 0.58)
continuumSide – “left” = bluewards of the line or “right” = redwards of the line
model – line model to be fitted : “gaussian”, “lorentz” or “pseudoVoigt”

Returns :

array 1 with the parameters of the model
array 2 with the model (wavelength, flux model)
header corresponding to the array 1

fit_Line_OIIdoublet_position_C0noise(wl, spec1d, err1d, a0=3726.0321, lineName='O2_3728', fitWidth=20, DLC=20, p0_sigma=4.0, p0_flux=1e-16, p0_share=0.58, model='gaussian')[source]¶

fits the [OII] doublet line profile

Parameters:

Parameters:	wl – wavelength (array, Angstrom) spec1d – flux observed in the broad band (array, f lambda) err1d – error on the flux observed in the broad band (array, f lambda) a0 – expected position of the peak of the line in the observed frame (redshifted). 2 positions given. lineName – suffix characterizing the line in the headers of the output DLC – wavelength extent to fit the continuum around the line. (def: 230 Angstrom) p0_sigma – prior on the line width in A (def: 15 A) p0_flux – prior on the line flux in erg/cm2/s/A (def: 8e-17) p0_share – prior on the share between the two [OII] lines. (def: 0.58) continuumSide – “left” = bluewards of the line or “right” = redwards of the line model – line model to be fitted : “gaussian”, “lorentz” or “pseudoVoigt”

wl – wavelength (array, Angstrom)
spec1d – flux observed in the broad band (array, f lambda)
err1d – error on the flux observed in the broad band (array, f lambda)
a0 – expected position of the peak of the line in the observed frame (redshifted). 2 positions given.
lineName – suffix characterizing the line in the headers of the output
DLC – wavelength extent to fit the continuum around the line. (def: 230 Angstrom)
p0_sigma – prior on the line width in A (def: 15 A)
p0_flux – prior on the line flux in erg/cm2/s/A (def: 8e-17)
p0_share – prior on the share between the two [OII] lines. (def: 0.58)
continuumSide – “left” = bluewards of the line or “right” = redwards of the line
model – line model to be fitted : “gaussian”, “lorentz” or “pseudoVoigt”

Returns :

array 1 with the parameters of the model
array 2 with the model (wavelength, flux model)
header corresponding to the array 1

fit_Line_position(wl, spec1d, err1d, a0=5007.0, lineName='AL', fitWidth=20, DLC=20, p0_sigma=15.0, p0_flux=8e-17, p0_share=0.5, continuumSide='left', model='gaussian')[source]¶

fits a line profile to a spectrum around a fixed line position

Parameters:

Parameters:	wl – wavelength (array, Angstrom) spec1d – flux observed in the broad band (array, f lambda) err1d – error on the flux observed in the broad band (array, f lambda) a0 – expected position of the peak of the line in the observed frame (redshifted). a0 is not fitted, it is given. lineName – suffix characterizing the line in the headers of the output DLC – wavelength extent to fit the continuum around the line. (def: 230 Angstrom) p0_sigma – prior on the line width in A (def: 15 A) p0_flux – prior on the line flux in erg/cm2/s/A (def: 8e-17) p0_share – prior on the share of Gaussian and Lorentzian model. Only used if the line is fitted with a pseudoVoigt profile width (def: 0.5 no units) continuumSide – “left” = bluewards of the line or “right” = redwards of the line model – line model to be fitted : “gaussian”, “lorentz” or “pseudoVoigt”.

wl – wavelength (array, Angstrom)
spec1d – flux observed in the broad band (array, f lambda)
err1d – error on the flux observed in the broad band (array, f lambda)
a0 – expected position of the peak of the line in the observed frame (redshifted). a0 is not fitted, it is given.
lineName – suffix characterizing the line in the headers of the output
DLC – wavelength extent to fit the continuum around the line. (def: 230 Angstrom)
p0_sigma – prior on the line width in A (def: 15 A)
p0_flux – prior on the line flux in erg/cm2/s/A (def: 8e-17)
p0_share – prior on the share of Gaussian and Lorentzian model. Only used if the line is fitted with a pseudoVoigt profile width (def: 0.5 no units)
continuumSide – “left” = bluewards of the line or “right” = redwards of the line
model – line model to be fitted : “gaussian”, “lorentz” or “pseudoVoigt”.

Returns :

array 1 with the parameters of the model
array 2 with the model (wavelength, flux model)
header corresponding to the array 1

fit_Line_position_C0noise(wl, spec1d, err1d, a0=5007.0, lineName='AL', fitWidth=20, DLC=20, p0_sigma=15.0, p0_flux=8e-17, p0_share=0.5, continuumSide='left', model='gaussian')[source]¶

fits a line profile to a spectrum where the error model is takes the value of the continuum.

Parameters:

Parameters:	wl – wavelength (array, Angstrom) spec1d – flux observed in the broad band (array, f lambda) err1d – error on the flux observed in the broad band (array, f lambda) a0 – expected position of the peak of the line in the observed frame (redshifted). a0 is fitted. lineName – suffix characterizing the line in the headers of the output fitWidth – width in Angstrom around the line where the fit is performed, default 20 Angstrom continuumSide – “left” = bluewards of the line or “right” = redwards of the line DLC – wavelength extent to fit the continuum around the line. (def: 230 Angstrom) p0_sigma – prior on the line width in A (def: 15 A) p0_flux – prior on the line flux in erg/cm2/s/A (def: 8e-17) p0_share – prior on the share of Gaussian and Lorentzian model. Only used if the line is fitted with a pseudoVoigt profile width (def: 0.5 no units) model – line model to be fitted : “gaussian”, “lorentz” or “pseudoVoigt”.

wl – wavelength (array, Angstrom)
spec1d – flux observed in the broad band (array, f lambda)
err1d – error on the flux observed in the broad band (array, f lambda)
a0 – expected position of the peak of the line in the observed frame (redshifted). a0 is fitted.
lineName – suffix characterizing the line in the headers of the output
fitWidth – width in Angstrom around the line where the fit is performed, default 20 Angstrom
continuumSide – “left” = bluewards of the line or “right” = redwards of the line
DLC – wavelength extent to fit the continuum around the line. (def: 230 Angstrom)
p0_sigma – prior on the line width in A (def: 15 A)
p0_flux – prior on the line flux in erg/cm2/s/A (def: 8e-17)
p0_share – prior on the share of Gaussian and Lorentzian model. Only used if the line is fitted with a pseudoVoigt profile width (def: 0.5 no units)
model – line model to be fitted : “gaussian”, “lorentz” or “pseudoVoigt”.

Returns :

array 1 with the parameters of the model
array 2 with the model (wavelength, flux model)
header corresponding to the array 1

fit_recLine(wl, spec1d, err1d, a0, lineName='AL', fitWidth=20, DLC=20, p0_sigma=5.0, p0_flux=5e-17, continuumSide='left')[source]¶

fits a recombination line profile : emission and absorption modeled by Gaussians. Only for high SNR spectra.

Parameters:

Parameters:	wl – wavelength (array, Angstrom) spec1d – flux observed in the broad band (array, f lambda) err1d – error on the flux observed in the broad band (array, f lambda) a0 – expected position of the peak of the line in the observed frame (redshifted) lineName – suffix characterizing the line in the headers of the output DLC – wavelength extent to fit the continuum around the line. (def: 230 Angstrom) p0_sigma – prior on the line width in A (def: 15 A) p0_flux – prior on the line flux in erg/cm2/s/A (def: 8e-17) continuumSide – “left” = bluewards of the line or “right” = redwards of the line

wl – wavelength (array, Angstrom)
spec1d – flux observed in the broad band (array, f lambda)
err1d – error on the flux observed in the broad band (array, f lambda)
a0 – expected position of the peak of the line in the observed frame (redshifted)
lineName – suffix characterizing the line in the headers of the output
DLC – wavelength extent to fit the continuum around the line. (def: 230 Angstrom)
p0_sigma – prior on the line width in A (def: 15 A)
p0_flux – prior on the line flux in erg/cm2/s/A (def: 8e-17)
continuumSide – “left” = bluewards of the line or “right” = redwards of the line

Returns :

array 1 with the parameters of the model
array 2 with the model (wavelength, flux model)
header corresponding to the array 1

getFractionObsMag(mag, lambdaMag, filter, xmin, xmax, wl, fl, flErr)[source]¶

Computes the fraction of light captured by the spectrograph in a broad band by comparing the integrated flux in the broad band to the magnitude.

Parameters:

Parameters:	mag – magnitude AB (float, mag) lambdaMag – mean wavelength covered by the magnitude AB (float, Angstrom) fl – flux observed in the broad band (array, f lambda) flErr – error on the flux observed in the broad band (array, f lambda) filt – filter curve (interpolation 1d) xmin – lower integration boundary (Angstrom) xmax – higher integration boundary (Angstrom)

mag – magnitude AB (float, mag)
lambdaMag – mean wavelength covered by the magnitude AB (float, Angstrom)
fl – flux observed in the broad band (array, f lambda)
flErr – error on the flux observed in the broad band (array, f lambda)
filt – filter curve (interpolation 1d)
xmin – lower integration boundary (Angstrom)
xmax – higher integration boundary (Angstrom)

Returns :

fraction of light observed
error on the fraction of light observed

getFractionObsMed(mag, lambdaMag, fl, flErr)[source]¶

Computes the fraction of light captured by the spectrograph in a broad band by comparing the median flux in the broad band to the magnitude converted to flux at the mean wavelength of the broad band.

Parameters:	mag – magnitude AB (float, mag) lambdaMag – mean wavelength covered by the magnitude AB (float, Angstrom) fl – flux observed in the broad band (array, f lambda) flErr – error on the flux observed in the broad band (array, f lambda)

Returns :

fraction of light observed
error on the fraction of light observed

integrateMAG(wl, spec1d, err1d, filt, xmin=5000.0, xmax=7500.0)[source]¶

Integrates a spectrum over a filter curve.

Parameters:	wl – wavelength (array) spec1d – flux, f lambda convention (array) err1d – flux error (array) filt – filter curve (interpolation 1d) xmin – lower integration boundary (Angstrom) xmax – higher integration boundary (Angstrom)

returns :

integral of filter curve
integral of spec1d
integral of spec1d * filter curve
integral of (spec1d + err1d) * filter curve
integral of (spec1d - err1d) * filter curve

plotLineFit(wl, fl, flErr, lineModel, a0, datI, path_to_fig='plot.pdf', title=' - ', fitWidth=70.0, DLC=50, doublet=False)[source]¶

Plots a spectrum and the emission line model fitted.

Parameters:	wl – wavelength (array, Angstrom) fl – flux observed in the broad band (array, f lambda) flErr – error on the flux observed in the broad band (array, f lambda) lineModel – model output by the line fitting functions (array, (2,N) wavelength and flux) a0 – position of the peak of the line path_to_fig – where you wish to save the figure