XMM-Newton spectrum of the radio-loud quasar 3C 215: slim accretion disk or SMBH binary?

TL;DR

This study analyzes XMM-Newton X-ray data of the radio-loud quasar 3C 215 to investigate its accretion disk structure and potential SMBH binary, proposing three possible scenarios including a slim disk or SMBH binary.

Contribution

It provides detailed spectral analysis of 3C 215, exploring its accretion and jet mechanisms, and introduces three novel scenarios for its inner structure.

Findings

Primary continuum photon index ~1.97

Evidence of jet contribution with photon index ~1.29

Ionized reflector with log ξ ≈ 2.31

Abstract

We want to explore the geometrical structure and mutual interactions of the innermost components of the broad line radio galaxy (BLRG) 3C 215, with particular interest in the accretion and ejection mechanisms involving the central supermassive black hole (SMBH). We compare these observational features with the ones of the RQ Seyfert 1 galaxies. Investigating their differences it is possible to understand more about the jet launching mechanisms, and why this phenomenon is efficient only in a small fraction of all the AGNs. Using high quality data from a $\sim60$ ks observation with XMM-Newton, we carried out a detailed X-ray spectral analysis of 3C 215 in the broad energy range $0.5-10$ keV. We modeled the spectrum with an absorbed double power-law model for the primary continuum, reprocessed by reflection from ionized and cold neutral material and modified by relativistic blurring. We also compared our results with the ones obtained with previous multi-wavelength observations. We obtain a primary continuum photon index from the corona $\Gamma_1=1.97\pm0.06$ and evidence of a jet contribution, modeled as a power law with photon index $\Gamma_2\simeq1.29$. The reflector, possibly the accretion disk and portions of the broad-line region (BLR), is ionized ($\log\xi=2.31_{-0.27}^{+0.37}\ \mathrm{erg\ s^{-1}\ cm}$) and relatively distant from the SMBH ($R_{in}>38\ R_g$), where $R_g=GM_{BH}/c^2$ is the gravitational radius. The obscuring torus seems patchy, dust-poor and inefficient, while the jet emission shows a twisted and knotted geometry. We propose three scenarios in order to describe these characteristics: 1.) ADAF state in the inner disk; 2.) Slim accretion disk; 3.) sub-pc SMBH binary system (SMBHB).