Molecular gas streamers feeding and obscuring the active nucleus of NGC1068

TL;DR

This study presents the first direct near-infrared observations of molecular gas streamers in NGC1068's nucleus, revealing gas inflow mechanisms and their role in fueling and obscuring the active galactic nucleus.

Contribution

It provides new direct imaging and kinematic evidence of molecular gas inflow and obscuration structures in NGC1068 at unprecedented spatial resolution.

Findings

Detected two linear molecular gas structures leading to the AGN.

Measured a radial gas transport rate of approximately 15 solar masses per year.

Identified a tidally disrupted streamer contributing to nuclear obscuration.

Abstract

We report the first direct observations of neutral, molecular gas streaming in the nucleus of NGC1068 on scales of <30 pc using SINFONI near-infrared integral field spectroscopy. At a resolution of 0.075", the flux map of 2.12 $\mu$m 1-0 S(1) molecular hydrogen emission around the nucleus in the central arcsec reveals two prominent linear structures leading to the AGN from the north and south. The kinematics of the gas in these features are dominated by non-circular motions and indicate that material is streaming towards the nucleus on highly elliptical or parabolic trajectories whose orientations are compatible with that of the disk plane of the galaxy. We interpret the data as evidence for fueling of gas to the central region. The radial transport rate from ~30 pc to a few parsec from the nucleus is ~15 M$_\sun$ yr$^{-1}$. One of the infalling clouds lies directly in front of the central engine. We interpret it as a tidally disrupted streamer that forms the optically thick outerpart of an amorphous clumpy molecular/dusty structure which contributes to the nuclear obscuration.