P92

class dust_extinction.shapes.P92(BKG_amp=218.57142857142858, BKG_lambda=0.047, BKG_b=90.0, BKG_n=2.0, FUV_amp=18.545454545454547, FUV_lambda=0.07, FUV_b=4.0, FUV_n=6.5, NUV_amp=0.05961038961038961, NUV_lambda=0.22, NUV_b=- 1.95, NUV_n=2.0, SIL1_amp=0.0026493506493506496, SIL1_lambda=9.7, SIL1_b=- 1.95, SIL1_n=2.0, SIL2_amp=0.0026493506493506496, SIL2_lambda=18.0, SIL2_b=- 1.8, SIL2_n=2.0, FIR_amp=0.015896103896103898, FIR_lambda=25.0, FIR_b=0.0, FIR_n=2.0, **kwargs)[source]

Bases: astropy.modeling.Fittable1DModel

Pei (1992) 24 parameter shape model

Parameters
BKG_ampfloat

background term amplitude

BKG_lambdafloat

background term central wavelength

BKG_bfloat

background term b coefficient

BKG_nfloat

background term n coefficient [FIXED at n = 2]

FUV_ampfloat

far-ultraviolet term amplitude

FUV_lambdafloat

far-ultraviolet term central wavelength

FUV_bfloat

far-ultraviolet term b coefficent

FUV_nfloat

far-ultraviolet term n coefficient

NUV_ampfloat

near-ultraviolet (2175 A) term amplitude

NUV_lambdafloat

near-ultraviolet (2175 A) term central wavelength

NUV_bfloat

near-ultraviolet (2175 A) term b coefficent

NUV_nfloat

near-ultraviolet (2175 A) term n coefficient [FIXED at n = 2]

SIL1_ampfloat

1st silicate feature (~10 micron) term amplitude

SIL1_lambdafloat

1st silicate feature (~10 micron) term central wavelength

SIL1_bfloat

1st silicate feature (~10 micron) term b coefficent

SIL1_nfloat

1st silicate feature (~10 micron) term n coefficient [FIXED at n = 2]

SIL2_ampfloat

2nd silicate feature (~18 micron) term amplitude

SIL2_lambdafloat

2nd silicate feature (~18 micron) term central wavelength

SIL2_bfloat

2nd silicate feature (~18 micron) term b coefficient

SIL2_nfloat

2nd silicate feature (~18 micron) term n coefficient [FIXED at n = 2]

FIR_ampfloat

far-infrared term amplitude

FIR_lambdafloat

far-infrared term central wavelength

FIR_bfloat

far-infrared term b coefficent

FIR_nfloat

far-infrared term n coefficient [FIXED at n = 2]

Notes

From Pei (1992, ApJ, 395, 130)

Applicable from the extreme UV to far-IR

Example showing a P92 curve with components identified.

import numpy as np
import matplotlib.pyplot as plt
import astropy.units as u

from dust_extinction.shapes import P92

fig, ax = plt.subplots()

# generate the curves and plot them
lam = np.logspace(-3.0, 3.0, num=1000)
x = (1.0/lam)/u.micron

ext_model = P92()
ax.plot(1/x,ext_model(x),label='total')

ext_model = P92(FUV_amp=0., NUV_amp=0.0,
                SIL1_amp=0.0, SIL2_amp=0.0, FIR_amp=0.0)
ax.plot(1./x,ext_model(x),label='BKG only')

ext_model = P92(NUV_amp=0.0,
                SIL1_amp=0.0, SIL2_amp=0.0, FIR_amp=0.0)
ax.plot(1./x,ext_model(x),label='BKG+FUV only')

ext_model = P92(FUV_amp=0.,
                SIL1_amp=0.0, SIL2_amp=0.0, FIR_amp=0.0)
ax.plot(1./x,ext_model(x),label='BKG+NUV only')

ext_model = P92(FUV_amp=0., NUV_amp=0.0,
                SIL2_amp=0.0)
ax.plot(1./x,ext_model(x),label='BKG+FIR+SIL1 only')

ext_model = P92(FUV_amp=0., NUV_amp=0.0,
                SIL1_amp=0.0)
ax.plot(1./x,ext_model(x),label='BKG+FIR+SIL2 only')

ext_model = P92(FUV_amp=0., NUV_amp=0.0,
                SIL1_amp=0.0, SIL2_amp=0.0)
ax.plot(1./x,ext_model(x),label='BKG+FIR only')

# Milky Way observed extinction as tabulated by Pei (1992)
MW_x = [0.21, 0.29, 0.45, 0.61, 0.80, 1.11, 1.43, 1.82,
        2.27, 2.50, 2.91, 3.65, 4.00, 4.17, 4.35, 4.57, 4.76,
        5.00, 5.26, 5.56, 5.88, 6.25, 6.71, 7.18, 7.60,
        8.00, 8.50, 9.00, 9.50, 10.00]
MW_x = np.array(MW_x)
MW_exvebv = [-3.02, -2.91, -2.76, -2.58, -2.23, -1.60, -0.78, 0.00,
             1.00, 1.30, 1.80, 3.10, 4.19, 4.90, 5.77, 6.57, 6.23,
             5.52, 4.90, 4.65, 4.60, 4.73, 4.99, 5.36, 5.91,
             6.55, 7.45, 8.45, 9.80, 11.30]
MW_exvebv = np.array(MW_exvebv)
Rv = 3.08
MW_axav = MW_exvebv/Rv + 1.0
ax.plot(1./MW_x, MW_axav, 'o', label='MW Observed')

ax.set_xscale('log')
ax.set_yscale('log')

ax.set_ylim(1e-3,10.)

ax.set_xlabel(r'$\lambda$ [$\mu$m]')
ax.set_ylabel(r'$A(x)/A(V)$')

ax.legend(loc='best')
plt.show()

(Source code, png, hires.png, pdf)

../_images/dust_extinction-shapes-P92-1.png

Attributes Summary

AbAv

BKG_amp

BKG_b

BKG_lambda

BKG_n

FIR_amp

FIR_b

FIR_lambda

FIR_n

FUV_amp

FUV_b

FUV_lambda

FUV_n

NUV_amp

NUV_b

NUV_lambda

NUV_n

SIL1_amp

SIL1_b

SIL1_lambda

SIL1_n

SIL2_amp

SIL2_b

SIL2_lambda

SIL2_n

fit_deriv

n_inputs

n_outputs

param_names

x_range

Methods Summary

__call__(self, *inputs[, model_set_axis, …])

Evaluate this model using the given input(s) and the parameter values that were specified when the model was instantiated.

evaluate(self, in_x, BKG_amp, BKG_lambda, …)

P92 function

Attributes Documentation

AbAv = 1.3246753246753247
BKG_amp = Parameter('BKG_amp', value=218.57142857142858, bounds=(0.0, None))
BKG_b = Parameter('BKG_b', value=90.0)
BKG_lambda = Parameter('BKG_lambda', value=0.047)
BKG_n = Parameter('BKG_n', value=2.0, fixed=True)
FIR_amp = Parameter('FIR_amp', value=0.015896103896103898, bounds=(0.0, None))
FIR_b = Parameter('FIR_b', value=0.0)
FIR_lambda = Parameter('FIR_lambda', value=25.0, bounds=(20.0, 30.0))
FIR_n = Parameter('FIR_n', value=2.0, fixed=True)
FUV_amp = Parameter('FUV_amp', value=18.545454545454547, bounds=(0.0, None))
FUV_b = Parameter('FUV_b', value=4.0)
FUV_lambda = Parameter('FUV_lambda', value=0.07, bounds=(0.06, 0.08))
FUV_n = Parameter('FUV_n', value=6.5)
NUV_amp = Parameter('NUV_amp', value=0.05961038961038961, bounds=(0.0, None))
NUV_b = Parameter('NUV_b', value=-1.95)
NUV_lambda = Parameter('NUV_lambda', value=0.22, bounds=(0.2, 0.24))
NUV_n = Parameter('NUV_n', value=2.0, fixed=True)
SIL1_amp = Parameter('SIL1_amp', value=0.0026493506493506496, bounds=(0.0, None))
SIL1_b = Parameter('SIL1_b', value=-1.95)
SIL1_lambda = Parameter('SIL1_lambda', value=9.7, bounds=(7.0, 13.0))
SIL1_n = Parameter('SIL1_n', value=2.0, fixed=True)
SIL2_amp = Parameter('SIL2_amp', value=0.0026493506493506496, bounds=(0.0, None))
SIL2_b = Parameter('SIL2_b', value=-1.8)
SIL2_lambda = Parameter('SIL2_lambda', value=18.0, bounds=(15.0, 21.0))
SIL2_n = Parameter('SIL2_n', value=2.0, fixed=True)
fit_deriv = None
n_inputs = 1
n_outputs = 1
param_names = ('BKG_amp', 'BKG_lambda', 'BKG_b', 'BKG_n', 'FUV_amp', 'FUV_lambda', 'FUV_b', 'FUV_n', 'NUV_amp', 'NUV_lambda', 'NUV_b', 'NUV_n', 'SIL1_amp', 'SIL1_lambda', 'SIL1_b', 'SIL1_n', 'SIL2_amp', 'SIL2_lambda', 'SIL2_b', 'SIL2_n', 'FIR_amp', 'FIR_lambda', 'FIR_b', 'FIR_n')
x_range = [0.001, 1000.0]

Methods Documentation

__call__(self, *inputs, model_set_axis=None, with_bounding_box=False, fill_value=nan, equivalencies=None, inputs_map=None, **new_inputs)

Evaluate this model using the given input(s) and the parameter values that were specified when the model was instantiated.

evaluate(self, in_x, BKG_amp, BKG_lambda, BKG_b, BKG_n, FUV_amp, FUV_lambda, FUV_b, FUV_n, NUV_amp, NUV_lambda, NUV_b, NUV_n, SIL1_amp, SIL1_lambda, SIL1_b, SIL1_n, SIL2_amp, SIL2_lambda, SIL2_b, SIL2_n, FIR_amp, FIR_lambda, FIR_b, FIR_n)[source]

P92 function

Parameters
in_x: float

expects either x in units of wavelengths or frequency or assumes wavelengths in wavenumbers [1/micron]

internally wavenumbers are used

Returns
axav: np array (float)

A(x)/A(V) extinction curve [mag]

Raises
ValueError

Input x values outside of defined range