Alma Resolves the Torus of NGC 1068: Continuum and Molecular Line Emission

Abstract

We present 450 and 850 μm submillimeter continuum observations of the IC 5146 star-forming region taken as part of the James Clerk Maxwell Telescope Gould Belt Survey. We investigate the location of bright submillimeter (clumped) emission with the larger-scale molecular cloud through comparison with extinction maps, and find that these denser structures correlate with higher cloud column density. Ninety-six individual submillimeter clumps are identified using FellWalker,and their physical properties are examined. These clumps are found to be relatively massive, ranging from 0.5  M to 116  M with a mean mass of 8  M and a median mass of 3.7  M . A stability analysis for the clumps suggests that the majority are (thermally) Jeans stable, withWe further compare the locations of known protostars with the observed submillimeter emission, finding that younger protostars, i.e., Class 0 and I sources, are strongly correlated with submillimeter peaks and that the clumps with protostars are among the most Jeans unstable. Finally, we contrast the evolutionary conditions in the two major star-forming regions within IC 5146: the young cluster associated with the Cocoon Nebula and the more distributed star formation associated with the Northern Streamer filaments. The Cocoon Nebula appears to have converted a higher fraction of its mass into dense clumps and protostars, the clumps are more likely to be Jeans unstable, and a larger fraction of these remaining clumps contain embedded protostars. The Northern Streamer, however, has a larger number of clumps in total and a larger fraction of the known protostars are still embedded within these clumps.

Disentangling the Circumnuclear Environs of Centaurus A. III. An Inner Molecular Ring, Nuclear Shocks, and the CO to Warm H2 Interface

“…For example, NGC 1068 hosts in its center a nuclear torus (García-Burillo et al 2016;Gallimore et al 2016), while NGC 1377 shows a hot compact core dominated by gas along the jet (Aalto et al 2017), which is extremely radio-quiet in contrast to the one in Cen A. A question that remains open is whether this difference reflects different steps in the evolutionary sequence or just simply different scenarios and morphologies.…”

The Intrinsic Far-infrared Continua of Type-1 Quasars

“…However, as suggested by, e.g., Antonucci (2015), one should be cautious when referring to a size of the torus since it depends on the observed wavelength. The Atacama Large Millimeter Array has the resolution to possibly image the torus structures in nearby systems (García-Burillo et al 2016;Imanishi et al 2016). Nevertheless, whether these dusty molecular clouds are obscuring the nuclei and heated up in the submillimeter bands by absorbing AGN emission is not easy to tell.…”

Spatially Resolved HCN Absorption Features in the Circumnuclear Region of NGC 1052

“…The size of the circumnuclear torus, however, is smaller than 10 pc (e.g. García-Burillo et al 2016), and a milliarcsecond (mas) resolution is required to study its internal structure in nearby AGNs. While conventional millimeter interferometers, even ALMA, did not achieve such a high angular resolution, VLBI observations have revealed the parsec-or subparsec-scale morphology of nearby AGNs.…”