ALMA Imaging of the CO(6-5) Line Emission in NGC 7130

TL;DR

This study presents high-resolution ALMA observations of CO(6-5) line emission and dust continuum in NGC 7130, revealing spatial offsets, negligible AGN heating contribution, and complex gas-star formation relationships at sub-100 pc scales.

Contribution

First high-resolution ALMA imaging of CO(6-5) and dust in NGC 7130, analyzing spatial offsets and AGN influence on molecular gas emission.

Findings

CO(6-5) and dust emissions are spatially correlated but offset by ~70 pc.

AGN contribution to CO(6-5) emission is negligible.

Large-scale CO(6-5) structure aligns with optical dust lanes.

Abstract

In this paper, we report our high-resolution ($0^{\prime\prime}.20\times0^{\prime\prime}.14$ or $\sim$$70\times49$ pc) observations of the CO(6-5) line emission, which probes warm and dense molecular gas, and the 434 $\mu$m dust continuum in the nuclear region of NGC 7130, obtained with the Atacama Large Millimeter Array (ALMA). The CO line and dust continuum fluxes detected in our ALMA observations are $1230\pm74$ Jy km s$^{-1}$ and $814\pm52$ mJy, respectively, which account for 100% and 51% of their total respective fluxes. We find that the CO(6-5) and dust emissions are generally spatially correlated, but their brightest peaks show an offset of $\sim$70 pc, suggesting that the gas and dust emissions may start decoupling at this physical scale. The brightest peak of the CO(6-5) emission does not spatially correspond to the radio continuum peak, which is likely dominated by an Active Galactic Nucleus (AGN). This, together with our additional quantitative analysis, suggests that the heating contribution of the AGN to the CO(6-5) emission in NGC 7130 is negligible. The CO(6-5) and the extinction-corrected Pa-$\alpha$ maps display striking differences, suggestive of either a breakdown of the correlation between warm dense gas and star formation at linear scales of $<$100 pc or a large uncertainty in our extinction correction to the observed Pa-$\alpha$ image. Over a larger scale of $\sim$2.1\,kpc, the double-lobed structure found in the CO(6-5) emission agrees well with the dust lanes in the optical/near-infrared images.