Warm absorber outflows in radio-loud active galactic nucleus 3C~59

TL;DR

This work presents a broadband spectral analysis of the radio-loud AGN 3C 59 to characterize two warm absorbers (WA_H and WA_L) using SPEX and PION, anchored by multiwavelength data from NIR to X-ray. The absorbers have NH ≈ 0.69×10^22 cm^-2 and 0.31×10^22 cm^-2, ξ ≈ 2.65 and 1.65, and v_out ≈ −528 and −228 km s^-1, placing them between the outer torus and the NLR. The study shows that the inferred WA properties depend on spectral fitting choices (e.g., including NIR–UV data and the adopted SED), but the v_out–ξ correlation is consistent with radiation-pressure-driven winds and mirrors the behavior seen in a radio-quiet AGN (NGC 3227), suggesting jets have a negligible role in driving these absorbers. Mass outflow rates and kinetic power imply negligible AGN feedback on the host galaxy, reinforcing a common driving mechanism across RL and RQ AGNs and providing a scalable methodological framework for analyzing larger samples. Overall, the paper delivers a rigorous, strategy-focused analysis that links WA properties to the central engine’s radiation field and sets the stage for broader comparative studies.

Abstract

Both jets and ionized outflows in active galactic nuclei (AGNs) are thought to play important roles in affecting the star formation and evolution of host galaxies, but their relationship is still unclear. As a pilot study, we performed a detailed spectral analysis for a radio-loud (RL) AGN 3C~59 ($z=0.1096$) by systematically considering various factors that may affect the fitting results, and thereby establishing a general spectral fitting strategy for subsequent research with larger sample. 3C~59 is one rare target for simultaneously studying jets and warm absorbers (WAs) that is one type of ionized outflows. Based on the multi-wavelength data from near-infrared (NIR) to hard X-ray bands detected by DESI, GALEX, and XMM-Newton, we used SPEX code to build broadband continuum models and perform photoionization modeling with PION code to constrain the physical parameters of WAs in 3C~59. We found two WAs with ionization parameter of $\log [ξ/(\rm{erg\ cm\ s}^{-1})] = 2.65^{+0.10}_{-0.09}$ and $1.65\pm 0.11$, respectively, and their outflowing velocities are $v_{\rm out} = -528^{+163}_{-222}\ \rm{km\ s}^{-1}$ and $-228^{+121}_{-122}\ \rm{km\ s}^{-1}$, respectively. These WAs are located between outer torus and narrow (emission-)line region, and their positive $v_{\rm out}$-$ξ$ relation can be explained by the radiation-pressure-driven mechanism. We found that the estimations of these physical properties are affected by the different spectral fitting strategies, such as the inclusion of NIR to ultra-violet data, the choice of energy range of spectrum, or the composition of the spectral energy distribution. Based on the same fitting strategy, this work presents a comparative study of outflow driven mechanism between a RL AGN (3C 59) and a radio-quiet AGN (NGC 3227), which suggests a similar driven mechanism of their WA outflows and a negligible role of jets in this process.

Figures (9)

• Figure 1: XMM-Newton spectra and the best-fit model with spex. The red points denote the RGS spectrum and the blue points represent the EPIC-pn spectrum. The solid black curve shows the best-fit model. For visualization purposes, here the RGS spectrum is binned by a factor of 10.
• Figure 2: The best-fit intrinsic SED models. The dotted orange line represents an accretion disk blackbody component (dbb). The dash-dotted green line denotes a warm Comptonization component (comt). The dashed blue line means an X-ray power-law component (pow). The dash-dotted red line shows a neutral X-ray reflection component (refl). The solid black line represents the total best-fit continuum model.
• Figure 3: The 13--20 Å RGS spectrum with main absorption features produced by the warm absorbers of 3C 59. The black points represent the RGS spectrum and the solid orange line denotes the best-fit model. The dashed blue lines and dotted red lines label the main absorption lines produced by the highly-ionized warm absorber (WA$_{\rm H}$) and the lowly-ionized warm absorber (WA$_{\rm L}$), respectively.
• Figure 4: Residual of spectral fitting with different models. The residual "(D-M)/E" means (data$-$model)$/$error. Top panel: The spectral fitting with only continuum models and the Galactic absorptions. Middle panel: The spectral fitting after adding the first pion model on the models shown in the top panel. This pion model is used to model the highly-ionized warm absorber. The $\Delta C$ here means the C-stat differential between the spectral fitting results in the top and middle panels. Bottom panel: The spectral fitting after adding the second pion model on the models shown in the middle panel. This pion model is used to model the lowly-ionized warm absorber. The $\Delta C$ here means the C-stat differential between the spectral fitting results in the middle and bottom panels.
• Figure 5: Distance of warm absorbers to the central BH in 3C 59. The solid blue and green lines represent the $n_{\rm H}$--$r$ distributions for WA$_{\rm H}$ and WA$_{\rm L}$, respectively. The markers "$\rhd$" and "$\lhd$" denote the lower and upper limits of $r$, respectively. The orange region means the size of broad (emission-)line region in 3C 59. The red region shows the size of torus in 3C 59. The dotted brown line represents the maximum distance of narrow (emission-)line region to the BH in 3C 59. We refer readers to Section \ref{['sec:distanceWA']} for detailed calculation of these sizes.