The warm absorber in the radio-loud quasar 4C +74.26

TL;DR

This study analyzes X-ray spectra of the radio-loud quasar 4C +74.26, revealing a photoionized outflow with specific properties, and clarifies that previous soft X-ray absorption was mainly due to Galactic interstellar medium.

Contribution

First detailed characterization of X-ray absorbing outflows in a broad line radio galaxy similar to Seyfert 1s, using joint XMM-Newton and Chandra data.

Findings

Detected a photoionized outflow with specific ionization and velocity parameters.

Located the absorber outside the broad line region but within the torus.

Found that past soft X-ray absorption was mainly Galactic in origin.

Abstract

Outflows of photoionized gas are commonly detected in the X-ray spectra of Seyfert 1 galaxies. However, the evidence for this phenomenon in broad line radio galaxies, which are analogous to Seyfert 1 galaxies in the radio-loud regime, has so far been scarce. Here, we present the analysis of the X-ray absorption in the radio-loud quasar 4C +74.26. With the aim of characterizing the kinetic and the ionization conditions of the absorbing material, we fitted jointly the XMM-Newton Reflection Grating Spectrometer (RGS) and the Chandra High Energy Transmission Grating Spectrometer (HETGS) spectra, which were taken 4 months apart. The intrinsic continuum flux did not vary significantly during this time lapse. The spectrum shows the absorption signatures (e.g., Fe-UTA, \ion{O}{vii}, and \ion{Ne}{vii}--\ion{Ne}{x}) of a photoionized gas outflow ($N_{\rm H} \sim 3.5 \times 10^{21} \rm cm^{-2}$, $\log \xi \sim 2.6$, $v_{\rm out}\sim 3600 \, \rm km \, s^{-1}$) located at the redshift of source. We estimate that the gas is located outside the broad line region but within the boundaries of the putative torus. This ionized absorber is consistent with the X-ray counterpart of a polar scattering outflow reported in the optical band for this source. The kinetic luminosity carried by the outflow is insufficient to produce a significant feedback is this quasar. Finally, we show that the heavy soft X-ray absorption that was noticed in the past for this source arises mostly in the Galactic ISM.