Possible evidence for shock-cooling in the accretion flow of the luminous Seyfert galaxy PG1211+143

TL;DR

This paper presents evidence of shock-cooling phenomena in the accretion flow of the Seyfert galaxy PG1211+143, linking observed variability and inflow signatures to shock-induced cooling in the inner disc.

Contribution

It provides the first observational indication of shock-cooling in the accretion flow of a luminous Seyfert galaxy, supporting models of disc warping and tearing due to high-inclination inflows.

Findings

Detection of variable thermal Comptonised spectrum consistent with shock cooling.

Identification of high velocity inflow supporting disc tearing and shock formation.

Evidence linking inner disc instabilities to observed spectral features.

Abstract

Short-term variability and multiple velocity components in the powerful highly ionized wind of the archetypal UFO PG1211+143 are indicative of inner disc instabilities or short-lived accretion events. The recent detection of a high velocity inflow 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. Here we identify a variable continuum component in the same data set, well-modelled by a hot thermal Comptonised spectrum that could represent cooling radiation from the shocked gas.