Empirical Galaxy Templates

Here we make publicly available our composite spectral energy distribution (SED) templates for AGN and star-forming galaxies. The creation of our empirical SEDs is described in detail Kirkpatrick et al. 2012, ApJ, 759, 139 - please cite this paper when using these templates.

We have a sample of 151 high redshift galaxies (z > 0.5) that were selected at 24 μm (80% have S₂₄ > 200 μJy) for which we have Spitzer mid-IR spectroscopy and deep Herschel far-IR/submm imaging. We performed spectral decomposition on the IRS spectra and classified our sources as AGN or star-formation (SF) dominated based on whether the mid-IR spectrum was dominated by a power-law or poly-cyclic aromatic hydrocarbon (PAH) emission. We further classified our sources into four subsamples: z~1 SF sources; z~2 SF sources; AGN with clear 9.7 μm silicate absorption; and AGN with featureless mid-IR spectra.

Within our subsamples, we created composite SEDs by stacking near-IR and mid-IR photometry and spectroscopy; in the far-IR, we fit a two temperature modified blackbody to the data. For the SF subsamples, we lack data in the range ~18-30 μm, so we have filled in that wavelength range by either extending the warm component of the two-temperature modified blackbody or linearly interpolating. Since we did not formally fit any data in this range, and this portion of the spectrum is for illustrative purposes only, we list the associated errors as 0.

We present three libraries of empirical SEDs created from dusty, infrared luminous galaxies at z=0.5-3. These template SEDs are designed for use with high redshift observations, in order to calculate L_IR, L_AGN, and other desired properties.

The creation of our infrared empirical templates is described in detail Kirkpatrick et al. (2015). The paper also discuss selection techniques and possible biases and should be read before using the templates. We have a sample of 343 high redshift galaxies, including the original 151 sources from Kirkpatrick et al. (2012) that were selected at 24 μm from the GOODS-N, ECDFS, and xFLS fields for which we have Spitzer IRS spectra. We performed spectral decomposition on the IRS spectra and quantified the amount of AGN emission (f (AGN)_MIR) to the infrared spectrum based on how much mid-IR luminosity is due to a power-law continuum, presumably arising from a hot dusty torus. We combine this spectroscopy with photometry from Spitzer IRAC and MIPS, Herschel PACS and SPIRE, and ground-based J and K.

We use these 343 sources to create three libraries of empirical templates. These libraries are not independent. Within each library, we first normalize sources by the mid-IR luminosity. We then determine the median L_ν of the photometry and spectroscopy in differential wavelength bins. In the far-IR, we fit a two temperature modified blackbody to the averaged data. Intrinsic properties of each template are listed in Tables 2 and 3 of Kirkpatrick et al. (2015).

Please cite Kirkpatrick et al. (2015) when using these templates.