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Markarian 817 is a bright and variable Seyfert-1.2 active galactic nucleus(AGN). X-ray monitoring of Mrk 817 with the Neil Gehrels Swift Observatory in2022 revealed that the source flux had declined to a lower level than recordedat any prior point in the then-19-year mission. We present an analysis of deepXMM-Newton and NuSTAR observations obtained in this low flux state. The spectrareveal a complex X-ray wind consisting of neutral and ionized absorption zones.Three separate velocity components are detected as part of a structuredultra-fast outflow (UFO), with v/c = 0.043 (+0.007,-0.003), v/c = 0.079(+0.003,-0.0008), and v/c = 0.074 (+0.004,-0.005). These projected velocitiessuggest that the wind likely arises at radii that are much smaller than theoptical broad line region (BLR). In order for each component of the outflow tocontribute significant feedback, the volume filling factors must be greaterthan f ~ 0.009, f ~ 0.003, and f ~ 0.3, respectively. For plausible,data-driven volume filling factors, these limits are passed, and the totaloutflow likely delivers the fierce feedback required to reshape its hostenvironment, despite a modest radiative Eddington fraction of lambda ~0.008-0.016 (this range reflects plausible masses). UFOs are often detected ator above the Eddington limit; this result signals that black hole accretion hasthe potential to shape host galaxies even at modest Eddington fractions, andover a larger fraction of a typical AGN lifetime. We discuss our findings interms of models for disk winds and black hole feedback in this and other AGN.

Fierce Feedback in an Obscured, Sub-Eddington State of the Seyfert 1.2 Markarian 817