The NIR to UV continuum of radio loud vs. radio quiet quasars

TL;DR

This study compares the spectral energy distributions of radio loud and radio quiet quasars across NIR to UV wavelengths, revealing significant differences in their continuum properties and spectral slopes.

Contribution

It provides the first large-scale comparison of the continuum properties of RLQ and RQQ quasars using SDSS and 2MASS data, highlighting their distinct spectral characteristics.

Findings

RLQs are redder than RQQs in their spectra.

Spectral indices differ significantly between RLQ and RQQ populations.

The continuum differences may be due to extinction, disc temperature, or non-thermal slopes.

Abstract

Starting from a sample of SDSS quasars appearing also in the 2MASS survey, we study the continuum properties of about 1000 objects observed in 8 bands, from NIR to UV. We construct the mean spectral energy distribution (SED) and compare and contrast the continua of radio loud (RLQ) and radio quiet (RQQ) objects. The SEDs of the two populations are significantly different in the sense that RLQs are redder, with power law spectral indices <alpha(RLQ)>=-0.55+/-0.04 and <alpha(RQQ)>=-0.31+/-0.01 in the spectral range between 10^14.5 and 10^15.35 Hz. This difference is discussed in terms of different extinctions, different disc temperatures, or slopes of the non-thermal component.