Disentangling the AGN and Star-Formation Contributions to the Radio-X-ray Emission of Radio-Loud Quasars at 1<z<2

TL;DR

This paper introduces ARXSED, a comprehensive spectral energy distribution fitting code that disentangles AGN and host galaxy emissions in radio-loud quasars at redshifts 1-2, revealing detailed physical properties and emission contributions.

Contribution

The study presents a novel, integrated SED fitting method that accurately models multiple emission components in radio-loud quasars, improving understanding of their emission mechanisms and physical parameters.

Findings

Non-thermal emission accounts for 57%-91% of submillimeter flux.

Over half the sources are predicted to have strong radio-linked X-ray emission.

Median black hole mass is estimated at 2.9×10^9 solar masses.

Abstract

We constrain the emission mechanisms responsible for the prodigious electromagnetic output generated by active galactic nuclei (AGN) and their host galaxies with a novel state-of-the-art AGN radio- to-X-ray spectral energy distribution model fitting code (ARXSED). ARXSED combines multiple components to fit the spectral energy distributions (SEDs) of AGN and their host galaxies. Emission components include radio structures such as lobes and jets, infrared emission from the AGN torus, visible-to-X-ray emission from the accretion disk, and radio-to-ultraviolet emission from the host galaxy. Applying ARXSED to the radio SEDs of 20 3CRR quasars at 1 < z < 2 verifies the need for more than a simple power law when compact radio structures are present. The non-thermal emission contributes 91%-57% of the observed-frame 1.25mm to 850{\mu}m flux, and this component must be accounted for when using these wavelengths to estimate star-formation properties. We predict the presence of strong radio-linked X-ray emission in more than half the sample sources. ARXSED estimates median (and the associated first and third quartile ranges) BH mass of $2.9_{1.7}^{6.0} \times 10^9~\rm M_{\odot}$, logarithm of Eddington ratio of $ -1.0_{-1.2}^{-0.6} $, and spin of $ 0.98_{0.94}^{0.99} $ for our sample. The inferred AGN torus and accretion disk parameters agree with those estimated from spectroscopic analyses of similar samples in the literature. We present the median intrinsic SED of the luminous radio-loud quasars at 1 < z < 2 ; this SED represents a significant improvement in the way each component is modeled.