greybody: Blackbody and Greybody Spectra

In asgr/ProSpect: Professional Spectral Analysis Package

Blackbody and Greybody Spectra

Description

Produces diferent types of blackbody and greybody spectra.

Usage

blackbody(wave, Temp = 50, k850 = 0.077)
blackbody_norm(wave, Temp = 50, z = 0, norm = 1)
greybody(wave, Temp = 50, beta = 1.5, k850 = 0.077)
greybody_norm(wave, Temp = 50, beta = 1.5, z = 0, norm = 1)

Arguments

wave	Observed wavelength in Angstroms.
Temp	Numeric vector; the absolute temperature of the system in Kelvin (K). For blackbody_norm and greybody_norm, if more than one value is provided then multiple black/greybodies are summed together to make a composite greybody spectrum.
z	Numeric scalar; cosmological redshift, where z must be > 0.
beta	Numeric vector; represents emissivity, or the spectral emissivity index. This is usually in the range 1-2 (see Hildebrand 1983). For blackbody_norm and greybody_norm, this should have the same number of elements as provided for Temp, but if length=1 then the values are recycled.
k850	Numeric scalar; the dust mass normalisation. The default is as used in MAGPHYS (0.077 kg/m^2). A sensible alternative might be 0.0383 (Draine 2003). The latter requires almost twice as much dust to achieve the same luminosity.
norm	Numeric vector; for blackbody_norm and greybody_norm, the integral of the returned black/greybody spectrum over all wavelength. By default it integrates to 1. This should have the same number of elements as provided for Temp, but if length=1 then the values are recycled.

Details

We use a modified version of Eqn 2 from Casey et al (2012). The idea is the normalised output can be scaled to equal any amount of required energy in a simple manner, i.e. if the difference between intrinsic and attenuated flux is known then this can be trivially mapped onto output greybody dust by scaling by this same factor using the norm argument (since both sets of fluxes are per angstrom).

Value

Numeric vector; observed luminosity in units Lsol / Ang (for 1 Msol of dust) for blackbody and greybody, and normalised as specified by norm for blackbody_norm and greybody_norm.

Author(s)

Aaron Robotham

References

Casey C.M., 2012, MNRAS, 425, 3094; da Cunha E. et al, 2008, MNRAS 388, 1595; Draine B.T., 2003, ARA&A, 41, 241; Hildebrand R.H., 1983, QJRAS, 24, 267

See Also

dust, Dale

Examples

#The greybody_norm function can take vector inputs:

plot(greybody_norm(10^seq(5,7,by=0.01), norm=1), type='l', log='x', col='grey',
ylim=c(0, 3e-6))
lines(greybody_norm(10^seq(5,7,by=0.01), Temp=100, norm=0.5), col='grey')
lines(greybody_norm(10^seq(5,7,by=0.01), Temp=c(50,100), norm=c(1,0.5)))

### Check against greybody template:

fluxBC03=Lum2Flux(BC03lr$Wave, BC03lr$Zspec[[5]][161,]*1e10)
birthBC03_atten=CF_birth_atten(fluxBC03[,1],fluxBC03[,2])
screenBC03_atten=CF_screen_atten(fluxBC03[,1],fluxBC03[,2])
totalatten=birthBC03_atten$total_atten+screenBC03_atten$total_atten

# Here we show 3 pure greybodies, and then 3 Dale templates normalised by SFR with
# differing amounts of AGN contribution. Note even the pure SFR template is not quite
# greybody (there is an excess in the MIR and very-FIR).

plot(fluxBC03, log='xy', xlab=BC03lr$Labels$Wavelab, ylab='Flux / erg/s/cm^2/Angstrom',
type='l', col='red', xlim=c(1e2,1e7))
lines(fluxBC03[,1], (birthBC03_atten$flux+screenBC03_atten$flux)/2, col='black')
lines(10^seq(5,7,by=0.01), greybody_norm(10^seq(5,7,by=0.01), beta=1, norm=totalatten),
col='brown', lty=1)
lines(10^seq(5,7,by=0.01), greybody_norm(10^seq(5,7,by=0.01), beta=1.5, norm=totalatten),
col='brown', lty=2)
lines(10^seq(5,7,by=0.01), greybody_norm(10^seq(5,7,by=0.01), beta=2, norm=totalatten),
col='brown', lty=3)
lines(Dale_NormSFR$Wave, Dale_NormSFR$Aspec[[1]][24,]*totalatten, col='purple')
lines(Dale_NormSFR$Wave, Dale_NormSFR$Aspec[[11]][24,]*totalatten, col='orange')
lines(Dale_NormSFR$Wave, Dale_NormSFR$Aspec[[20]][24,]*totalatten, col='green')

asgr/ProSpect documentation built on Feb. 21, 2025, 1:43 a.m.