DOI: 10.7910/dvn/lpuhiq
title: PAH emission: Dependence on Starlight Spectrum, Intensity, PAH Size Distribution, and PAH Ionization
title: A Library of Model Emission Spectra

description: &lt;HTML&gt;
&lt;h3&gt;Excitation of PAH Emission: Dependence on Starlight Spectrum,
Intensity, PAH Size Distribution, and PAH Ionizations&lt;/h3&gt;&lt;br&gt;

The emission spectra provided here are from the paper
"Excitation of PAH Emission: Dependence on Starlight Spectrum, Intensity,
PAH Size Distribution, and PAH Ionization" (Draine, Li, Hensley, Hunt, Sandstrom, & Smith 2021, Astrophysical Journal, in press). 
Please cite that paper if you use these data.&lt;br&gt;
Preprint available at https://arxiv.org/abs/2011.07046
&lt;br&gt;
We consider 14 different radiation spectra:

&lt;ul&gt;
&lt;li&gt; mmpisrf : mMMP spectrum (see Draine, Li, Hensley et al 2021) 
&lt;li&gt; bc03_z0.02_3e6 : BC03 3 Myr old stellar population with Z=0.02
&lt;li&gt; bc03_z0.0004_1e7 : BC03 10 Myr old stellar population with Z=0.0004
&lt;li&gt; bc03_z0.02_1e7 : BC03 10 Myr old stellar population with Z=0.02
&lt;li&gt; bc03_z0.02_1e8 : BC03 100 Myr old stellar population with Z=0.02
&lt;li&gt; bc03_z0.02_3e8 : BC03 300 Myr old stellar population with Z=0.02
&lt;li&gt; bc03_z0.02_1e9 : BC03 1 Gyr old stellar population with Z=0.02
&lt;li&gt; bpass_z0.02_3e6 : BPASS 3 Myr old stellar population with Z=0.02
&lt;li&gt; bpass_z0.001_1e7 : BPASS 10 Myr old stellar population with Z=0.001
&lt;li&gt; bpass_z0.02_1e7 : BPASS 10 Myr old stellar population with Z=0.02
&lt;li&gt; bpass_z0.02_1e8 : BPASS 100 Myr old stellar population with Z=0.02
&lt;li&gt; bpass_z0.02_3e8 : BPASS 300 Myr old stellar population with Z=0.02
&lt;li&gt; bpass_z0.02_1e9 : BPASS 1 Gyr old stellar population with Z=0.02
&lt;li&gt; m31blge : M31 bulge spectrum
&lt;br&gt;&lt;br&gt;&lt;/ul&gt;
Note:&lt;br&gt;
&lt;ul&gt;The mMMP ("modified Mathis, Mezger & Panagia") spectrum is based on Mathis, Mezger & Panagia (1983), with parameters modified as described in Draine (2011).&lt;br&gt;
The BC03 model spectra for 
single-age stellar populations are from Bruzual & Charlot (2003)&lt;br&gt;
The BPASS model spectra for single-age stellar populations with 
binary evolution are from Eldridge et al. (2017) and 
Stanway & Eldridge (2018)&lt;br&gt;
The M31 bulge spectrum uses the spectrum obtained by Groves et al. (2012) for the bulge of M31.&lt;br&gt;&lt;br&gt;
The above spectra are all shown in Figure 1 of Draine, Li, Hensley et al (2021).&lt;br&gt;
Each spectrum (for intensity parameter U=1) is included in a file in the appropriate library (see below).
&lt;/ul&gt;

We calculate heating of dust grains, and resulting infrared emission, 
for each of the above radiation fields,
for selected values of the dimensionless intensity scaling parameter U,
where U=1 corresponds to an intensity such that a "standard grain" (taken to be
an 1.6:1 oblate spheroid of "astrodust" with a_eff=0.10um, b/a=1.6, and
porosity P=0.2) is heated at the same rate as in the modified MMP
estimate for the starlight intensity in the solar neighborhood [see
Draine (2011) or Draine, Li, Hensley et al (2021) for discussion of the mMMP
spectrum].&lt;br&gt;&lt;br&gt;

The PAH properties are almost identical to the model of Draine & Li (2007), but with some small adjusts in bandstrengths for features at 14.19um, 17.04um, 17.375um, and 17.87um (see Draine, Li, Hensley et al (2021).&lt;br&gt;&lt;br&gt;
For the properties of "astrodust", see Draine & Hensley (2021).&lt;br&gt;&lt;br&gt;

We also calculate heating of dust grains, and resulting infrared emission, 
for dust distributed in a "slab" of total
thickness A_V = 2 mag. The radiation incident on the cloud surface is
assumed to be from one of the above-listed spectra, with an intensity
at the cloud surface characterized by the scaling parameter U. The cloud is
illuminated on one side only.
The dust slab is divided
into 20 zones, with the radiation attenuated and reddened as it
propagates into the cloud, as described in Draine, Li, Hensley et al
(2021).&lt;br&gt;&lt;br&gt;


Results are presented for values of lgU = log10(U) = 0.00, 0.50, 1.00,
..., 6.50, 7.00 &lt;br&gt;
&lt;br&gt;

The results for each of the different spectra are located in different
libraries. We provide gzipped tarfiles containing complete results for each of the starlight models:

&lt;ul&gt;
mMMP.tgz&lt;br&gt;
BC03_Z0.02_3Myr.tgz&lt;br&gt;
BC03_Z0.0004_10Myr.tgz&lt;br&gt;
BC03_Z0.02_10Myr.tgz&lt;br&gt;
BC03_Z0.02_100Myr.tgz&lt;br&gt;
BC03_Z0.02_300Myr.tgz&lt;br&gt;
BC03_Z0.02_1Gyr.tgz&lt;br&gt;
BPASS_Z0.02_3Myr.tgz&lt;br&gt;
BPASS_Z0.001_10Myr.tgz&lt;br&gt;
BPASS_Z0.02_10Myr.tgz&lt;br&gt;
BPASS_Z0.02_100Myr.tgz&lt;br&gt;
BPASS_Z0.02_300Myr.tgz&lt;br&gt;
BPASS_Z0.02_1Gyr.tgz&lt;br&gt;
m31bulge.tgz&lt;br&gt;
&lt;/ul&gt;
We also provide libraries for models with starlight incident on a cloud with A_V=2mag of extinction:
&lt;ul&gt;
mMMP_slab.tgz&lt;br&gt;
BC03_Z0.02_3Myr_slab.tgz&lt;br&gt;
BC03_Z0.0004_10Myr_slab.tgz&lt;br&gt;
BC03_Z0.02_10Myr_slab.tgz&lt;br&gt;
BC03_Z0.02_100Myr_slab.tgz&lt;br&gt;
BC03_Z0.02_300Myr_slab.tgz&lt;br&gt;
BC03_Z0.02_1Gyr_slab.tgz&lt;br&gt;
BPASS_Z0.02_3Myr_slab.tgz&lt;br&gt;
BPASS_Z0.001_10Myr_slab.tgz &lt;br&gt;
BPASS_Z0.02_10Myr_slab.tgz&lt;br&gt;
BPASS_Z0.02_100Myr_slab.tgz&lt;br&gt;
BPASS_Z0.02_300Myr_slab.tgz&lt;br&gt;
BPASS_Z0.02_1Gyr_slab.tgz&lt;br&gt;
m31bulge_slab.tgz&lt;br&gt;
&lt;/ul&gt;


Each library contains files of four different types:

&lt;ul&gt;
&lt;li&gt; Emission spectra for selected radiation fields, PAH size distributions,
and PAH ionizations, e.g., the mMMP library includes

&lt;ul&gt;
&lt;li&gt; pahspec.out_mmpisrf_0.00_st_std.gz :
mMMP starlight with
lgU=0.00, "standard" PAH ionization ("st"), and 
"standard" PAH size distribution ("std")

&lt;li&gt; pahspec.out_mmpisrf_0.00_st_sma.gz :
mMMP starlight with
lgU=0.00, standard PAH ionization ("st"), and 
"small" PAH size distribution ("sma")

&lt;li&gt; pahspec.out_mmpisrf_0.00_st_lrg.gz :
mMMP starlight with
lgU=0.00, standard PAH ionization ("st"), and 
"large" PAH size distribution ("lrg")

&lt;li&gt; pahspec.out_mmpisrf_0.00_hi_std.gz :
mMMP starlight with
lgU=0.00, "high" PAH ionization ("hi"), and 
"standard" PAH size distribution ("std")

&lt;li&gt; pahspec.out_mmpisrf_0.00_hi_sma.gz :
mMMP starlight with
lgU=0.00, "high" PAH ionization ("hi"), and 
"small" PAH size distribution ("sma")

&lt;li&gt; pahspec.out_mmpisrf_0.00_hi_lrg.gz :
mMMP starlight with
lgU=0.00, "high" PAH ionization ("hi"), and 
"large" PAH size distribution ("lrg")

&lt;li&gt; pahspec.out_mmpisrf_0.00_lo_std.gz :
mMMP starlight with
lgU=0.00, "low" PAH ionization ("lo"), and 
"standard" PAH size distribution ("std")

&lt;li&gt; pahspec.out_mmpisrf_0.00_lo_sma.gz :
mMMP starlight with
lgU=0.00, "low" PAH ionization ("lo"), and 
"small" PAH size distribution ("sma")

&lt;li&gt; pahspec.out_mmpisrf_0.00_lo_lrg.gz :
mMMP starlight with
lgU=0.00, "low" PAH ionization ("lo"), and 
"large" PAH size distribution ("lrg")
&lt;br&gt;&lt;br&gt;
&lt;/ul&gt;

&lt;li&gt; Emission spectra for individual dust grains, heated by selected
radiation fields and intensities, e.g., 

&lt;ul&gt;
&lt;li&gt; iout_graD16emtPAHib_mmpisrf_0.00.gz :
PAH^+ particles of different sizes, heated by mMMP radiation spectrum
with lgU=0.00 

&lt;li&gt; iout_graD16emtPAHnb_mmpisrf_0.00.gz :
PAH^0 particles of different sizes, heated by mMMP radiation spectrum
with lgU=0.00 

&lt;li&gt; iout_DH21Ad_P0.20_0.00_mmpisrf_0.00.gz :
DH21 astrodust with porosity 0.20, oblate spheroids with b/a=1.6: particles of different sizes, heated by mMMP radiation spectrum
with lgU=0.00 &lt;br&gt;&lt;br&gt;

&lt;/ul&gt;

&lt;li&gt; Starlight spectra used in the calculations, e.g.,&lt;br&gt;
&lt;ul&gt;
&lt;li&gt; isrf_mmpisrf_0.00.gz :
mMMP starlight spectrum with lgU=0.00&lt;br&gt;&lt;br&gt;
&lt;/ul&gt;

&lt;li&gt; Grain sizes, and abundance for each size, for Astrodust, PAH+, and PAH0 used in the calculations, e.g.,
&lt;ul&gt;
&lt;li&gt; pahspec_dnda.out_st_std :
"standard" ionization and "standard" PAH size distribution

&lt;li&gt; pahspec_dnda.out_st_sma :
"standard" ionization and "small" PAH size distribution

&lt;li&gt; pahspec_dnda.out_st_lrg :
"standard" ionization and "large" PAH size distribution

&lt;li&gt; pahspec_dnda.out_hi_std :
"high" ionization and "standard" PAH size distribution

&lt;li&gt; pahspec_dnda.out_hi_sma :
"high" ionization and "small" PAH size distribution

&lt;li&gt; pahspec_dnda.out_hi_lrg :
"high" ionization and "large" PAH size distribution

&lt;li&gt; pahspec_dnda.out_lo_std :
"low" ionization and "standard" PAH size distribution

&lt;li&gt; pahspec_dnda.out_lo_sma :
"low" ionization and "small" PAH size distribution

&lt;li&gt; pahspec_dnda.out_lo_lrg :
"low" ionization and "large" PAH size distribution

&lt;/ul&gt;
&lt;/ul&gt;


&lt;STRONG&gt;References:&lt;/STRONG&gt;
&lt;ul&gt; 
Bruzual, G, & Charlot, S. 2003, MNRAS, 344, 1000&lt;br&gt;
Draine, B.T. 2011, Physics of the Interstellar and Intergalactic Medium
(Princeton: Princeton University Press)&lt;br&gt;
Draine, B.T., & Hensley, B.S. 2021, ApJ, 909:94&lt;br&gt;
Draine, B.T., & Li, A. 2007, ApJ, 657, 810&lt;br&gt;
Draine, B.T., Li, A., Hensley, B.S., Hunt, L.K., Sandstrom, K., and 
Smith, J.-D.T 2021, ApJ, in press, https://ui.adsabs.harvard.edu/abs/2020arXiv201107046D/abstract&lt;br&gt;
Eldridge, J.J., Stanway, E.R., Xiao, L., et al. 2017, PASA, 34, e058&lt;br&gt;
Groves, B., Krause, O., Sandstrom, K. et al. 2012, MNRAS, 426, 892&lt;br&gt;
Mathis, J.S., Mezger, P.G., & Panagia, N. 1983, A&A, 128, 212&lt;br&gt;
Stanway, E.R., & Eldridge, J.J. 2018, MNRAS, 479, 75&lt;br&gt;
&lt;/ul&gt;

&lt;HR&gt;&lt;HR&gt;

&lt;STRONG&gt;Description of files:&lt;/STRONG&gt; &lt;br&gt;

&lt;HR&gt;

&lt;STRONG&gt;1. Emission Spectra for Individual Grain sizes:&lt;/STRONG&gt;&lt;br&gt;
Filenames:&lt;br&gt;
&lt;li&gt; iout_dusttype_startype_lgU.gz
&lt;li&gt; iout_dusttype_startype_lgU_slab.gz&lt;br&gt;&lt;br&gt;

where dusttype = 
&lt;ul&gt;
&lt;li&gt; graD16emtPAHib for PAH ions
&lt;li&gt; graD16emtPAHnb for PAH neutrals
&lt;li&gt; DH21Ad_P0.20_0.00 for DH21 Astrodust, P=0.20, f_Fe=0
&lt;br&gt;
&lt;/ul&gt;

startype = 
&lt;ul&gt;
&lt;li&gt; mmpisrf : mMMP spectrum (see Draine, Li, Hensley et al 2021) 
&lt;li&gt; bc03_z0.02_3e6 : BC03 3 Myr old stellar population with Z=0.02
&lt;li&gt; bc03_z0.0004_1e7 : BC03 10 Myr old stellar population with Z=0.0004
&lt;li&gt; bc03_z0.02_1e7 : BC03 10 Myr old stellar population with Z=0.02
&lt;li&gt; bc03_z0.02_1e8 : BC03 100 Myr old stellar population with Z=0.02
&lt;li&gt; bc03_z0.02_3e8 : BC03 300 Myr old stellar population with Z=0.02
&lt;li&gt; bc03_z0.02_1e9 : BC03 1 Gyr old stellar population with Z=0.02
&lt;li&gt; bpass_z0.02_3e6 : BPASS 3 Myr old stellar population with Z=0.02
&lt;li&gt; bpass_z0.001_1e7 : BPASS 10 Myr old stellar population with Z=0.001
&lt;li&gt; bpass_z0.02_1e7 : BPASS 10 Myr old stellar population with Z=0.02
&lt;li&gt; bpass_z0.02_1e8 : BPASS 100 Myr old stellar population with Z=0.02
&lt;li&gt; bpass_z0.02_3e8 : BPASS 300 Myr old stellar population with Z=0.02
&lt;li&gt; bpass_z0.02_1e9 : BPASS 1 Gyr old stellar population with Z=0.02
&lt;li&gt; m31blge : M31 bulge spectrum
&lt;br&gt;
&lt;/ul&gt;

lgU = log_10(U)
 = 0.00 0.50 1.00 1.50 2.00 2.50 3.00 3.50 4.00 4.50 5.00 5.50
 6.00 6.50 7.00
&lt;br&gt;&lt;br&gt; 

file structure for N = 1 - 167 [a = 3.548e-8 cm to 5.012e-4 cm] 
 in 40 steps per decade in particle radius: &lt;br&gt;
&lt;ul&gt; 
 lines 1-3 : comments &lt;br&gt;
 line 4 + (N-1)*2511 : description of starlight spectrum &lt;br&gt;
 line 5: (N-1)*2511 :blank &lt;br&gt;
 line 6 + (N-1)*2511 : a(cm) = 10.**(-7.45+0.025*(N-1)) &lt;br&gt; 
 lines 7-14 + (N-1)*2511 : comments &lt;br&gt;
 lines 15-2514 + (N-1)*2511:&lt;br&gt;
&lt;ul&gt; column 1: lambda (um) &lt;br&gt;
 column 2: nu * P_nu (erg s-1) [P_nu = time-averaged power per unit frequency for one particle]&lt;br&gt;
 column 3: C_abs (cm2) [absorption cross section for one particle] &lt;br&gt;
&lt;/ul&gt;&lt;/ul&gt;

&lt;HR&gt;

&lt;STRONG&gt; 2. Emission Spectra Summed over Simple Dust Model for a Single U,
 for Dust Abundance per H Appropriate for the Local Diffuse ISM:
&lt;/STRONG&gt;&lt;br&gt;
Filenames:&lt;br&gt;
&lt;li&gt; pahspec.out_startype_lgU_fion_fsize.gz
&lt;li&gt; pahspec.out_startype_lgU_slab_fion_fsize.gz&lt;br&gt;&lt;br&gt;


where 
&lt;ul&gt;
startype is as above&lt;br&gt;
fion = lo, st, hi for low, standard, high f_ion&lt;br&gt;
fsize = sma, std, lrg for small, standard, large size distribution&lt;br&gt;
&lt;/ul&gt;

file structure:&lt;br&gt; 
&lt;ul&gt; 
 line 1: description of radiation field&lt;br&gt;
 line 2: TIR power radiated by Astrodust (erg s-1 per H)&lt;br&gt;
 line 3: TIR power radiated by PAH^+ (erg s-1 per H)&lt;br&gt;
 line 4: TIR power radiated by PAH^0 (erg s-1 per H)&lt;br&gt;
 line 5: total TIR power radiated (erg s-1 per H)&lt;br&gt;
 lines 6-7: comments&lt;br&gt;
 lines 8-1980: (1973 wavelengths from 1.0056 um to 8000um) &lt;br&gt;
&lt;ul&gt; column 1: wave (um)&lt;br&gt;
 column 2: nu*P_nu (total) (erg s-1 per H) [P_nu=power radiated per unit frquency per H]&lt;br&gt;
 column 3: nu*P_nu (Astrodust only) (erg s-1 per H)&lt;br&gt;
 column 4: nu*P_nu (PAH^+ only) (erg s-1 per H)&lt;br&gt;
 column 5: nu*P_nu (PAH^- only) (erg s-1 per H)&lt;br&gt;
&lt;/ul&gt;&lt;/ul&gt;

&lt;HR&gt;

&lt;STRONG&gt;3. PAH Ionization and Size Distributions 
Used in Computing pahspec.out:&lt;/STRONG&gt;&lt;br&gt;
Filenames:&lt;br&gt;

&lt;li&gt; pahspec_dnda.out_fion_fsize&lt;br&gt;&lt;br&gt;


where 
&lt;ul&gt; fion = lo, st, hi for low, standard, or high PAH ionization&lt;br&gt;
 fsize = sma, std, lrg for small, standard, large PAH size distribution&lt;br&gt;
&lt;/ul&gt;

file structure:&lt;br&gt;
&lt;ul&gt;
 lines 1-3: comments&lt;br&gt;
 lines 4-170:&lt;br&gt;
&lt;ul&gt; column 1: a_eff (um)&lt;br&gt;
 column 2: dn_Ad = astrodust number per H in this bin&lt;br&gt;
 column 3: dn_PAH+ = PAH^+ number per H in this bin&lt;br&gt;
 column 4: dn_PAH0 = PAH^0 number per H in this bin&lt;br&gt;
&lt;/ul&gt;&lt;/ul&gt;

&lt;HR&gt;

&lt;STRONG&gt;4. Unreddened Starlight Spectra Used in Calculations for U = 1 :
&lt;/STRONG&gt;&lt;br&gt;
Filenames:&lt;br&gt;

&lt;li&gt; isrf_startype_0.00.gz&lt;br&gt;&lt;br&gt;
where&lt;br&gt;
&lt;ul&gt; startype is as above&lt;br&gt;


file structure:&lt;br&gt;
&lt;ul&gt;
 line 1: comments&lt;br&gt;
 line 2: U&lt;br&gt;
 line 3: u = u_starlight+u_CMB = photon energy density (erg cm-3)&lt;br&gt;
 line 4: u_starlight = starlight energy density (erg cm-3)&lt;br&gt;
 line 5: &lt; h nu &gt; = mean photon energy (eV) [including CMB photons]&lt;br&gt;
 line 6-7: comments&lt;br&gt;
 lines 8-2507: &lt;br&gt;
&lt;ul&gt; column 1: lambda (um)&lt;br&gt;
 column 2: lambda*u_lambda (erg cm-3)&lt;br&gt;
&lt;/ul&gt;&lt;/ul&gt;&lt;/ul&gt;
&lt;HR&gt;