We present the results of IRS low-resolution spectroscopy of 51 Seyfert galaxies, part of a large Spitzer observing program to determine the mid-to-far infrared spectral energy distributions of a well-defined sample of 87 nearby, 12 µm-selected Seyferts. We find that the spectra clearly divide into groups based on their continuum shapes and spectral features. The infrared spectral types appear to be related to the Seyfert types. Some features are clearly related to a starburst contribution to the IR spectrum, while the observed power-law continuum shapes, attributed to the AGN, may be dust or non-thermal emission. Principal component analysis results suggest that the relative contribution of starburst emission is the dominant cause of variance in the spectra. We find that the Sy 2’s show on average stronger starburst contributions than the Sy 1’s. (Refer to PDF file for exact formulas).

Date of creation, presentation, or exhibit



This is the pre-print of a paper published by the Astronomical Society of the Pacific. The final, published version is available here:

Presented at The Second Annual Spitzer Science Center Conference: Infrared Diagnostics of Galaxy Evolution.

© 2008 Astronomical Society of the Pacific

Also archived in: arXiv:astro-ph/0603442 v1 16 Mar 2006

Support for this work was provided by NASA through an award issued by JPL/Caltech.

Note: imported from RIT’s Digital Media Library running on DSpace to RIT Scholar Works in February 2014.

Document Type

Conference Paper

Department, Program, or Center

School of Physics and Astronomy (COS)


RIT – Main Campus