radiocont: Radio Emission Extension

In asgr/ProSpect: Professional Spectral Analysis Package

Radio Emission Extension

Description

Can take an output ProSpect spectrum and extend it into the radio regime using a mixture of free-free (thermal) and synchrotron (non-thermal) radio emission. Default values are sensible for typical galaxies, and reproduce the Dale template emission.

Usage

radiocont(wave, flux, z = 0, Te = 10000, ff_frac = 0.1, ff_power = -0.1, 
    sy_power = -0.8, wavesamp = seq(6, 9.4, by = 0.1), flux_in = "freq", 
    flux_out = flux_in, subtractonly = FALSE) 

Arguments

wave	Numeric vector; observed wavelength in Angstroms. For convenience, if a two column matrix or data frame is supplied then the first column is taken to be wave and the second is taken to be flux.
flux	Numeric vector; flux spectral density in per Hz or per Ang units (see flux_in and flux_out).
z	Numeric scalar; the redshift of the input spectrum (usually only relevant for observed frame flux spectra, not rest frame luminosity spectra).
Te	Numeric scalar; effective HII nebular plasma temperature in Kelvin. Leave as the default (10,000 K), unless you know what you are doing.
ff_frac	Numeric scalar; free-free HII nebular plasma thermal radio emission contribution fraction at 1.4 Ghz (should be between 0.05 and 0.2 typically). By defintion the radio synchrotron emission fraction at 1.4 Ghz will be 1 - ff_frac.
ff_power	Numeric scalar; power-law slope of the free-free nebular plasma thermal radio emission. Leave as the default (-0.1), unless you know what you are doing.
sy_power	Numeric scalar; power-law slope of the synchrotron radio emission (should be between -0.8 and -0.6 typically).
wavesamp	Numeric vector; desired output log10 wavelength radio emission grid to use in Ang. The default covers the FIR the 1.4 Ghz range, so is usually appropriate for the radio SED extension.
flux_in	Character scalar; the input type of flux spectral density used. Should be either 'freq' (default, power per Hz) or 'wave' (power per Ang)
flux_out	Character scalar; the output type of flux spectral density desired. Should be either 'freq' (default, power per Hz) or 'wave' (power per Ang)
subtractonly	Logical; if true then only subtracts the Dale template radio emission, if false also adds on new radio emission.

Details

This radio continuum extension for ProSpect is mostly based on the work of Marvil et al (2015).

The default options closely reproduce the Dale template radio emission. The advantage of using this interface is the user has fine control over the free-free and synchrotron radio emission mixing (which is fixed to 1:9 at 1.4 Ghz in the Dale templates), and also control over the power-law indices (fixed to -0.1 and -0.8 respectively in the Dale templates).

Condon & Yin (1990) suggest that ff_frac is seen to typically span the range 0.05 to 0.2, so it should probably be kept within these limits for generative and fitting purposes.

Value

Numeric Matrix; first column is observed wavelength (Angstroms) and second column is observed flux in the units of flux_out.

Author(s)

Aaron Robotham

References

Condon & Yin, 1990. ApJ, 357, 97
Marvil et al, 2015, AJ, 149, 32

See Also

Dale

Examples

data('BC03lr')
data('Dale_NormTot')
data('AGN_UnOb_Sparse')
data('Dale_M2L_func')
filters=c('FUV_GALEX', 'NUV_GALEX', 'u_SDSS', 'g_SDSS', 'r_SDSS', 'i_SDSS',
  'Z_VISTA', 'Y_VISTA', 'J_VISTA', 'H_VISTA', 'K_VISTA', 'W1_WISE' , 'W2_WISE',
  'W3_WISE', 'W4_WISE', 'P100_Herschel', 'P160_Herschel', 'S250_Herschel' ,
  'S350_Herschel', 'S500_Herschel')
filtout={}
for(i in filters){filtout=c(filtout,list(approxfun(getfilt(i))))}

testSED = ProSpectSED(z=0.05, AGNlum=0, tau_birth=1, tau_screen=0.3,
                    alpha_SF_birth=0.5, alpha_SF_screen=3, speclib=BC03lr, 
                    Dale=Dale_NormTot, AGN=AGN_UnOb_Sparse, filtout=filtout, 
                    Dale_M2L_func=Dale_M2L_func, returnall=TRUE)

# The defaults almost recreate the Dale template emission:

temp = radiocont(testSED$FinalFlux$wave, testSED$FinalFlux$flux, z=0.05)
plot(temp, log='xy', type='l', ylim=c(1e-6,1), xlab='Wave / Ang',
  ylab='Flux Density / Jy', lwd=3)
lines(testSED$FinalFlux$wave, testSED$FinalFlux$flux, col='red')

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