Infrared Spectra and Spectral Energy Distributions for Dusty Starbursts
  and AGN
  We present spectroscopic results for all galaxies observed with the Spitzer
Infrared Spectrograph (IRS) which also have total infrared fluxes f(ir)
measured with the Infrared Astronomical Satellite (IRAS), also using AKARI
photometry when available. Infrared luminosities and spectral energy
distributions (SEDs) from 8 um to 160 um are compared to polycyclic aromatic
hydrocarbon (PAH) emission from starburst galaxies or mid-infrared dust
continuum from AGN at rest frame wavelengths ~ 8 um. A total of 301 spectra are
analyzed for which IRS and IRAS include the same unresolved source, as measured
by the ratio fv(IRAS 25 um)/fv(IRS 25 um). Sources have 0.004 < z < 0.34 and
42.5 < log L(IR) < 46.8 (erg per s) and cover the full range of starburst
galaxy and AGN classifications. Individual spectra are provided electronically,
but averages and dispersions are presented. We find that log [L(IR)/vLv(7.7
um)] = 0.74 +- 0.18 in starbursts, that log [L(IR)/vLv(7.7 um)] = 0.96 +- 0.26
in composite sources (starburst plus AGN), that log [L(IR)/vLv(7.9 um)] = 0.80
+- 0.25 in AGN with silicate absorption, and log [L(IR)/vLv(7.9 um)] = 0.51 +-
0.21 in AGN with silicate emission. L(IR) for the most luminous absorption and
emission AGN are similar and 2.5 times larger than for the most luminous
starbursts. AGN have systematically flatter SEDs than starbursts or composites,
but their dispersion in SEDs overlaps starbursts. Sources with the strongest
far-infrared luminosity from cool dust components are composite sources,
indicating that these sources may contain the most obscured starbursts.
