Parsec-scale Dusty Winds in Active Galactic Nuclei: Evidence for Radiation Pressure Driving

TL;DR

This study investigates how radiation pressure influences the distribution of dusty winds in active galactic nuclei by analyzing VLTI/MIDI data and correlating dust emission with Eddington ratios.

Contribution

It provides the first quantitative analysis linking radiation pressure to dust wind distribution in a comprehensive AGN sample using interferometric data.

Findings

Higher Eddington ratios correlate with increased dust in the wind.

Evidence suggests radiation pressure impacts dust distribution, especially in type 2 AGN.

Supports the disk+wind model over the traditional dust torus model.

Abstract

Infrared interferometry of local AGN has revealed a warm (~300K-400K) polar dust structure that cannot be trivially explained by the putative dust torus of the unified model. This led to the development of the disk+wind scenario which comprises of a hot (~1000K) compact equatorial dust disk and a polar dust wind. This wind is assumed to be driven by radiation pressure and, therefore, we would expect that long term variation in radiation pressure would influence the dust distribution. In this paper we attempt to quantify if and how the dust distribution changes with radiation pressure. We analyse so far unpublished VLTI/MIDI data on 8 AGN and use previous results on 25 more to create a sample of 33 AGN. This sample comprises all AGN successfully observed with VLTI/MIDI. For each AGN, we calculate the Eddington ratio, using the intrinsic 2-10keV X-ray luminosity and black hole mass, and compare this to the resolved dust emission fraction as seen by MIDI. We tentatively conclude that there is more dust in the wind at higher Eddington ratios, at least in type 2 AGN where such an effect is expected to be more easily visible.