Spitzer/IRS 5-35 um Low-Resolution Spectroscopy of the 12 um Seyfert
  Sample
  We present low-resolution 5.5-35 um spectra for 103 galaxies from the 12 um
Seyfert sample, a complete unbiased 12 um flux limited sample of local Seyfert
galaxies selected from the IRAS Faint Source Catalog, obtained with the
Infrared Spectrograph (IRS) on-board Spitzer Space Telescope. For 70 of the
sources observed in the IRS mapping mode, uniformly extracted nuclear spectra
are presented for the first time. We performed an analysis of the continuum
emission, the strength of the Polycyclic Aromatic Hydrocarbon (PAH) and
astronomical silicate features of the sources. We find that on average, the
15-30 um slope of the continuum is alpha_{15-30}=-0.85+-0.61 for Seyfert 1s and
-1.53+-0.84 for Seyfert 2s, and there is substantial scatter in each type.
Moreover, nearly 32% of Seyfert 1s, and 9% of Seyfert 2s, display a peak in the
mid-infrared spectrum at 20 um, which is attributed to an additional hot dust
component. The PAH equivalent width decreases with increasing dust temperature,
asindicated by the global infrared color of the host galaxies. However, no
statistical difference in PAH equivalent width is detected between the two
Seyfert types, 1 and 2, of the same bolometric luminosity. The silicate
features at 9.7 and 18um in Seyfert 1 galaxies are rather weak, while Seyfert
2s are more likely to display strong silicate absorption. Those Seyfert 2s with
the highest silicate absorption also have high infrared luminosity and high
absorption (hydrogen column density N_H>10^23 cm^-2 as measured from the
X-rays. Finally, we propose a new method to estimate the AGN contribution to
the integrated 12 um galaxy emission, by subtracting the "star formation"
component in the Seyfert galaxies, making use of the tight correlation between
PAH 11.2 um luminosity and 12 um luminosity for star forming galaxies.
