Fast inflowing ionized absorber tracing the gas dynamics at sub-parsec scale around Mrk 3

TL;DR

Using high-resolution X-ray spectroscopy from Chandra HETG and XMM-Newton RGS, the study probes gas dynamics in the inner sub-parsec around the Mrk 3 SMBH. It detects a fast, redshifted ionized absorber with Fe XXV and Fe XXVI absorption lines located at roughly 0.04–0.74 pc, with inflow velocity decreasing from about 6,100 km/s to 3,400 km/s over 11 years. Photoionization modeling indicates only about 0.6%–3% of the inflowing material reaches the event horizon, and a soft X-ray component at 0.86 keV with sub-solar metallicity traces shocked ISM in the NLR. The coexistence of a decelerating sub-parsec inflow and an NLR outflow supports a coherent scenario where a disk wind or BLR clouds impede or eject accretion, linking the torus to the inner accretion disk and informing AGN fueling dynamics.

Abstract

Accretion onto supermassive black hole (SMBH) can release energy via radiation, jets or winds, providing feedback effects on the circumnuclear gas environment. However, not all active galactic nuclei (AGNs) exhibit clear signature of such feedback, and the dynamics of accreting gas on the inner sub-parsec scales remains poorly understood. Using high-resolution Chandra X-ray grating spectra of Mrk 3, we detect a fast inflowing ionized absorber characterized by redshifted Fe XXV and Fe XXVI absorption lines with confidence level in the $94-99.6\%$ range. Photoionization modeling reveals the inflowing absorber is located at $\lesssim0.04-0.74\rm~pc$, with red-shifted velocity decreasing from $6.1\pm0.5\times10^3\rm~km~s^{-1}$ to $3.4\pm0.3\times10^3\rm~km~s^{-1}$ over 11 years. Only $\sim0.6$\%--$3$\% of the inflowing material is estimated to reach the event horizon. This direct evidence of sub-parsec scale fueling inflow bridges the gap between the torus and the outer accretion disk. Additionally, a $0.86$-keV gas component with sub-solar metallicity ($Z\sim0.22$), outflowing at a velocity of $\sim330\rm~km~s^{-1}$, is detected in the soft X-ray band from XMM-Newton Reflection Grating Spectrometer, probably corresponding to shocked interstellar medium in the narrow-line region (NLR). The simultaneous presence of the apparent decelerating sub-parsec inflow and the NLR outflow favors a coherent scenario where a putative disk wind or broad-line region clouds may impede or even eject the accretion material, although other possibilities cannot be fully excluded.