A fast and long-lived outflow from the supermassive black hole in NGC 5548

TL;DR

This study reports a unique, long-lasting, and fast ionized outflow from the supermassive black hole in NGC 5548, revealing new insights into the dynamics and structure of active galactic nuclei winds.

Contribution

It uncovers a previously unseen, long-lived, clumpy ionized outflow with higher velocities, originating close to the black hole, based on multi-observatory data from 2013.

Findings

Obscuration of 90% of soft X-ray emission by the outflow

Detection of outflow velocities up to five times faster than previous persistent outflows

Outflow likely originates from the accretion disk, only a few light days from the nucleus

Abstract

Supermassive black holes in the nuclei of active galaxies expel large amounts of matter through powerful winds of ionized gas. The archetypal active galaxy NGC 5548 has been studied for decades, and high-resolution X-ray and UV observations have previously shown a persistent ionized outflow. An observing campaign in 2013 with six space observatories shows the nucleus to be obscured by a long-lasting, clumpy stream of ionized gas never seen before. It blocks 90% of the soft X-ray emission and causes simultaneous deep, broad UV absorption troughs. The outflow velocities of this gas are up to five times faster than those in the persistent outflow, and at a distance of only a few light days from the nucleus, it may likely originate from the accretion disk.