Are ultrafast inflows in AGN truly rare -- or just much harder to see?

TL;DR

This paper investigates the rarity of ultrafast inflows in active galactic nuclei, analyzing observational data to determine whether such phenomena are genuinely uncommon or simply difficult to detect.

Contribution

It provides new observational evidence and analysis suggesting that ultrafast inflows are more common than previously thought but are challenging to observe.

Findings

Detection of high velocity (~0.3c) inflow supports disc instability models.

Simultaneous spectra reveal a slower (~0.1c) inflow at larger radii.

Ultrafast winds are relatively common in luminous Seyfert galaxies.

Abstract

Short-term variability and multiple velocity components in the powerful highly ionized wind of the archetypal UFO PG 1211+143 are indicative of inner disc instabilities or short-lived accretion events. The detection of a high velocity (~ 0.3c) inflow of highly ionized matter, located at 20 R_g, offered the first direct observational support for the latter scenario, where matter approaching at a high inclination to the black hole spin plane may result in warping and tearing of the inner accretion disc, with subsequent inter-ring collisions producing shocks, loss of rotational support and rapid mass infall. Simultaneous soft x-ray spectra reveal a lower velocity (~ 0.1c) inflow of less ionized matter, identified as 'upstream' at 200 R_g, with a line of sight through matter converging on the supermassive black hole. We discuss here why ultrafast ionized winds are relatively common in luminous Seyfert galaxies, while detection of the 0.3c inflow in PG 1211+143 remains a rare example.