SpectrumTemplate¶

class grizli.utils.SpectrumTemplate(wave=None, flux=None, central_wave=None, fwhm=None, velocity=False, fluxunits=Unit('erg / (Angstrom s cm2)'), waveunits=Unit('Angstrom'), name='template', lorentz=False, err=None)[source]¶

Bases: object

Container for template spectra.

Parameters

wavearray-like: Wavelength In astropy.units.Angstrom.
fluxfloat array-like: If float, then the integrated flux of a Gaussian line. If array, then f-lambda flux density.
central_wave, fwhmfloat: Initialize the template with a Gaussian at this wavelength (in astropy.units.Angstrom.) that has an integrated flux of flux and fwhm in astropy.units.Angstrom or km/s for velocity=True.
velocitybool: fwhm is a velocity in km/s.
fluxunitsastropy.units.Unit: Units of the flux. Default is FLAMBDA_CGS (1e-17 erg/s/cm^2/Angstrom).
waveunitsastropy.units.Unit: Units of the wavelength. Default is Angstrom.
namestr: Name of the template. Default is “template”.
lorentzbool: Make a Lorentzian line instead of a Gaussian.
errfloat array-like, optional: Error on the flux.

Examples

Include-source

import matplotlib.pyplot as plt

ha = SpectrumTemplate(central_wave=6563., fwhm=10) plt.plot(ha.wave, ha.flux)

ha_z = ha.zscale(0.1) plt.plot(ha_z.wave, ha_z.flux, label=’z=0.1’)

plt.legend() plt.xlabel(r’$lambda$’) plt.xlim(6000, 7500)

plt.show()

Attributes

wave, fluxarray-like: Passed from the input parameters or generated/modified later.

Methods

__add__, __mul__

(Addition and multiplication of templates.)

Attributes Summary

eazy

Convert to eazy.template.Template object

Methods Summary

`integrate_filter`(filter[, abmag, use_wave])	Integrate the template through an `FilterDefinition` filter object.
`make_gaussian`(central_wave, fwhm[, ...])	Make Gaussian template
`to_fnu`([fnu_units])	Make fnu version of the template.
`zscale`(z[, scalar, apply_igm])	Redshift the template and multiply by a scalar.

Attributes Documentation

eazy¶: Convert to eazy.template.Template object

Methods Documentation

integrate_filter(filter, abmag=False, use_wave='filter')[source]¶

Integrate the template through an FilterDefinition filter object.

Parameters

filterObsBandpass: Or any object that has wave and throughput attributes, with the former in the same units as the input spectrum.
abmagbool: Return AB magnitude rather than fnu flux
use_wavestr, optional: Determines whether to interpolate the template to the filter wavelengths or the spectrum wavelengths. Default is ‘filter’.

Returns

temp_fluxfloat

Examples

Compute the WFC3/IR F140W AB magnitude of a pure emission line at the 5-sigma 3D-HST line detection limit (5e-17 erg/s/cm2):

>>> import numpy as np
>>> from grizli.utils import SpectrumTemplate
>>> from eazy.filters import FilterDefinition
>>> import pysynphot as S
>>> line = SpectrumTemplate(central_wave=1.4e4, fwhm=150.,
                velocity=True)*5.e-17
>>> filter = FilterDefinition(bp=S.ObsBandpass('wfc3,ir,f140w'))
>>> fnu = line.integrate_filter(filter)
>>> print('AB mag = {0:.3f}'.format(-2.5*np.log10(fnu)-48.6))
AB mag = 26.619

static make_gaussian(central_wave, fwhm, max_sigma=5, step=0.1, wave_grid=None, velocity=False, clip=1e-06, lorentz=False)[source]¶

Make Gaussian template

Parameters

central_wave, fwhmNone or float or array-like

Central wavelength and FWHM of the desired Gaussian

velocitybool

fwhm is a velocity.

max_sigma, stepfloat

Generated wavelength array is

>>> rms = fwhm/2.35
>>> xgauss = np.arange(-max_sigma, max_sigma, step)*rms+central_wave

clipfloat

Clip values where the value of the gaussian function is less than clip times its maximum (i.e., 1/sqrt(2*pi*sigma**2)).

lorentzbool

Make a Lorentzian line instead of a Gaussian.

Returns

wave, fluxarray-like: Wavelength and flux of a Gaussian line

to_fnu(fnu_units=Unit('erg / (Hz s cm2)'))[source]¶

Make fnu version of the template.

Sets the flux_fnu attribute, assuming that the wavelength is given in Angstrom and the flux is given in flambda:

>>> flux_fnu = self.flux * self.wave**2 / 3.e18

zscale(z, scalar=1, apply_igm=True)[source]¶

Redshift the template and multiply by a scalar.

Parameters

zfloat: Redshift to use.
scalarfloat: Multiplicative factor. Additional factor of 1/(1+z) is implicit.
apply_igmbool: Apply the intergalactic medium (IGM) attenuation correction.

Returns

new_spectrumSpectrumTemplate: Redshifted and scaled spectrum.

Navigation

SpectrumTemplate¶