# The Intrinsic Far-infrared Continua of Type-1 Quasars

## TL;DR

This study refines the understanding of the intrinsic far-infrared emission of type-1 quasars, showing a consistent SED shape that aids in separating AGN and host galaxy contributions in infrared observations.

## Contribution

It develops tests to validate AGN IR templates and demonstrates that a modified Elvis et al. (1994) template accurately represents the intrinsic far-IR emission of type-1 quasars.

## Key findings

- The intrinsic far-IR emission drops off rapidly starting at ~20 μm.
- AGN in quasars and Seyfert galaxies have similar far-IR SEDs at 20-100 μm.
- Variations in IR SEDs are due to changing dust component strengths.

## Abstract

The range of currently proposed active galactic nucleus (AGN) far-infrared templates results in uncertainties in retrieving host galaxy information from infrared observations and also undermines constraints on the outer part of the AGN torus. We discuss how to test and reconcile these templates. Physically, the fraction of the intrinsic AGN IR-processed luminosity compared with that from the central engine should be consistent with the dust-covering factor. In addition, besides reproducing the composite spectral energy distributions (SEDs) of quasars, a correct AGN IR template combined with an accurate library of star-forming galaxy templates should be able to reproduce the IR properties of the host galaxies, such as the luminosity-dependent SED shapes and aromatic feature strengths. We develop tests based on these expected behaviors and find that the shape of the AGN intrinsic far-IR emission drops off rapidly starting at $\sim20~\mu$m and can be matched by an Elvis et al. (1994)-like template with minor modification. Despite the variations in the near- to mid-IR bands, AGNs in quasars and Seyfert galaxies have remarkably similar intrinsic far-IR SEDs at $\lambda \sim 20$-$100~\mu$ m, suggesting similar emission character of the outermost region of the circumnuclear torus. The variations of the intrinsic AGN IR SEDs among the type-1 quasar population can be explained by the changing relative strengths of four major dust components with similar characteristic temperatures, and there is evidence for compact AGN-heated dusty structures at sub-kpc scales in the far-IR.