Far-Infrared Properties of Type 1 Quasars

TL;DR

This study constructs a comprehensive infrared spectral energy distribution template for type 1 quasars using multi-survey data, revealing a consistent power-law at shorter wavelengths and an infrared excess at longer wavelengths.

Contribution

It provides the first statistically robust rest-frame 0.1-100 micron quasar template combining Spitzer, SDSS, and 2MASS data, highlighting infrared excesses beyond simple power-law models.

Findings

Quasar SEDs follow a power-law below 20 microns.

Infrared luminosity exceeds the power-law at wavelengths near 100 microns.

Significant object-to-object dispersion in the infrared SEDs.

Abstract

We use the Spitzer Space Telescope Enhanced Imaging Products (SEIP) and the Spitzer Archival Far-InfraRed Extragalactic Survey (SAFIRES) to study the spectral energy distributions of spectroscopically confirmed type 1 quasars selected from the Sloan Digital Sky Survey (SDSS). By combining the Spitzer and SDSS data with the 2-Micron All Sky Survey (2MASS) we are able to construct a statistically robust rest-frame 0.1-100 micron type 1 quasar template. We find the quasar population is well-described by a single power-law SED at wavelengths less than 20 microns, in good agreement with previous work. However, at longer wavelengths we find a significant excess in infrared luminosity above an extrapolated power-law, along with signifiant object-to-object dispersion in the SED. The mean excess reaches a maximum of 0.8 dex at rest-frame wavelengths near 100 microns.