An image of the dust sublimation region in the nucleus of NGC 1068

TL;DR

This study uses near-infrared interferometry to image the dust sublimation region in NGC 1068, revealing a thin ring structure inconsistent with a thick torus and suggesting a shared origin with the maser disc.

Contribution

First high-resolution infrared image of the dust sublimation region in NGC 1068, challenging traditional torus models and linking it to the maser disc.

Findings

Revealed a 0.24 pc radius ring-like dust structure

Observed morphology inconsistent with a thick torus

Identified a shared origin with the maser disc

Abstract

We present near-infrared interferometric data on the Seyfert 2 galaxy NGC 1068, obtained with the GRAVITY instrument on the European Southern Observatory Very Large Telescope Interferometer. The extensive baseline coverage from 5 to 60 M\lambda allowed us to reconstruct a continuum image of the nucleus with an unrivaled 0.2 pc resolution in the K-band. We find a thin ring-like structure of emission with a radius r = 0.24+/-0.03 pc, inclination i = 70+/-5 deg, position angle PA = -50+/-4 deg, and h/r < 0.14, which we associate with the dust sublimation region. The observed morphology is inconsistent with the expected signatures of a geometrically and optically thick torus. Instead, the infrared emission shows a striking resemblance to the 22 GHz maser disc, which suggests they share a common region of origin. The near-infrared spectral energy distribution indicates a bolometric luminosity of (0.4-4.7) x 10^45 erg/s, behind a large A_K ~ 5.5 (A_V ~ 90) screen of extinction that also appears to contribute significantly to obscuring the broad line region.